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This invention describes a process for the production of crystalline aluminosilicate zeolites
having the N structure. The products of this process are novel compositions of matter with
exceptional selectivity for ion exchange of certain species from solutions. These novel
products demonstrate physical and chemical characteristics attributable to the method of
production. Zeolite N materials of this invention maybe used as components of ion-exchange
processes; as adsorbents; as molecular sieves or as catalytic materials. Modification of the
surface of zeolite N with surfactants allows the material to adsorb anionic species. Thus, this
novel material can be used in numerous industrial, agricultural, environmental, health and
medical applications.
BACKGROUND OF THE INVENTION
Zeolites are three-dimensional, microporous, crystalline solids with well-defined structures
that typically contain aluminium, silicon, and oxygen in a regular framework; cations and
water are located within the framework pores. A representative formula for a zeolite is:
MzAAAIzOa-X SiO2.Y H2O
where M ~ the exchangeable cation, n represents the cation valence, x is equal to or greater
than 2 and Y is the level of hydration. Zeolites are classified in terms of their framework
structure type.
Zeolites with Si:AI ratio between 1.0 and 2.0 such as zeolite A, zeolite P, zeolite X and zeolite
F have been synthesized at industrial scale. General descriptions of the zeolite groups are
detailed in texts by Breck (1974) and Szosak (1998) and prior art referred to in the attached
Bibliography is fully incorporated Into this specification by way of reference.
The crystal structure of hydro-thermally synthesised zeolite N has been determined by
Christensen and Fjellvag (1997) using synchrotron X-ray powder diffraction. This work and a
subsequent study (Christensen and Fjellvag, 1999), used laboratory-scale quantities of
zeolite 4A, sodium aluminosilicate gel and potassium chloride heated in an autoclave at
300°C for 7 days to crystallise zeolite N from a static solution. Structural studies show that
zeolite N is orthorhombic with space group I222. Cell dimensions for hydro-thermally
synthesised zeolite N are a = 9.9041(2), b = 9.8860(2), c = 13.0900(2) with the composition
Ki2AlioSi1004oC!z.8H20 (Christensen and Fjelivag, 1997).
Potassium exchanged aluminosilicates have received little attention in the prior art compared
to the commonly available sodium exchanged zeolites. Barrer identified a group of potassic
zeolites including zeolite F and a form which is now known as zeolite N. Synthetic zeolite K-F
2
described by Barrer et a/., (1953) and Barrer and Baynham (1956) was structurally defined by
Baerlocher and Barrer (1974) in the sodium exchanged form. Further work on potassium-
derived zeolites by Barrer and Marcilly (1970) defined salt-bearing forms of zeolites within the
K-F structure type. These aforementioned syntheses were generally via hydrothermal
crystallisation or re-crystallisation of minerals or gels at temperatures greater than 100°C in
an autoclave.
Low yields of zeolite K-F(CI) by hydrothermal recrystallisation of analcite and leucite with
excess KCI is described by Barrer and Marcilly (1970). Barrer and Marcilly (1970) obtained
good yields of zeolite K-F(CI) by hydrothermal synthesis from crystalline Linde Na-X at
temperatures between 200°C and 400°C. Higher yields are obtained at temperatures close to
400°C. Barrer and Marcilly (1970) found that this synthesis procedure using the clay mineral
kaolinite yields kaliophyllite at T > 200°C. Barrer and Marcilly (1970) used X-ray diffraction
data to suggest that these hydro-thermally synthesised zeolites are a tetragonal zeolite K-F
structure. However, more recent work by Christensen and Fjellvag (1997) shows that the
product synthesised under these conditions in the presence of excess KCI is orthorhombic
zeolite N.
A process for the production of X-ray amorphous aluminosilicates or kaolin derivatives
obtained by the chemical modification of clay minerals and other aluminium-bearing minerals
is described in US 6,218,329 and US 5,858,081. In these disclosures, the modification of
clay minerals to form alumlnosilicate or kaolin derivatives involves the mixing of a caustic
reactant in the form of an alkali halide, alkali metal halide, alkali hydroxide or alkali m9tal
hydroxide, or combinations of these reactants, with a clay such as kaolin in the presence of
water at temperatures less than 200°C and preferably less than 100°C. As disclosed in US
6,218,329 and US 5,858,081, for certain reactions trace amounts of zeolite and other
crystalline aluminosilicates such as kalsilite and kaliophyllite may form in addition to the
amorphous aluminosilicate. However, the primary phase is an amorphous (i.e. non-
crystalline) aluminosilicate.
The nomenclature for zeolites has evolved over a period of decades since the early discovery
of hydrothermal synthesis routes by Barren The term "zeolite N" as disclosed in US
3,414,602 and US 3,306,922 was initially used to designate an ammonium or alky!
ammonium substituted cationlc species. However, this nomenclature to describe alkyl
ammonium or ammonium substituted species is no longer practised In order to avoid
confusion (Szostak,1998). Sherman (1977) describes the confusion at the time with
nomenclature for eleven zeolites synthesised in the K2O-AI2O3-SiO2-H2O system and clarifies
relationships for Linde F and zeolite K-F. However, zeolite N is not described in this work by
Sherman (1977).
3
SUMMARY OF THE INVENTION
This invention relates to the surprising discovery of a process using caustic solutions and
. aluminosilicates such as kaolin and/or montmorillonite which results in the production of
zeolite N by a non-hydrothermal synthesis route. The invention also relates to manufacture of
zeolites with the N structure of many different compositions and in forms characterized by
physical properties not previously known.
In one aspect of the present invention there is provided a process for making aluminosilicates
of zeolite N structure including the steps of:
(i) combining a water soluble monovalent cation with a solution of hydroxyl
anions and an aluminosilicate to form a resultant mixture having a pH greater than 10 and a
H2O/AI203 ratio in the range 30 to 220;
(ii) heating the resultant mixture to a temperature of between 50°C and the
boiling point of the mixture for a time of between 1 minute and 100 hours until a crystalline
product of zeolite N structure is formed as determined by X-ray diffraction or other suitable
characteristic; and
(iii) separating the zeolite N product as a solid from the mixture.
Preferably the water soluble monovalent cation used in step (i) comprises an alkali m9tal
such as potassium or sodium or ammonium ion or mixtures of these ions such as sodium
and potassium. However it will be appreciated that the alkali metal may also comprise Li, Rb
or Cs. Preferably the alkali metal is potassium. The solution of suitable anions may have a
pH greater than 13.
If desired the resultant mixture of step (i) may also include haiide ion such as chloride and in
this embodiment the haiide may have an alkali metal cation or monovalent soluble cation
which may include potassium, sodium or ammonium or mixtures thereof such as sodium and
potassium. It will also be appreciated that the alkali metal may also comprise Li, Rb or Cs.
Preferably the alkali metal is potassium.
In step (i) the aluminosilicate may have an Si:AI ratio in the range 1.0 to 5.0 and more
preferably in the range 1.0 to 3.0.
In step (ii) the heating step is preferably carried out at temperatures in the range 80°C to -
95°C. Preferably the reaction time is in the range 2 to 24 hours.
In step (iii) the solid product may be separated from the caustic liquor by suitable means such
as, for example, by washing or filtration.
■ 4
Surprisingly, zeolites of N structure are formed at low temperature (less than 100°C) and
without use of potassium chloride as an essential starting reactant as taught in the prior art.
Contrary to prior art, zeolite N may be formed in the presence of caustic solutions such as
KOH or NaOH although alkali halides such as NaCI may also be present.
The disclosed process enables the production of many varieties of zeolite with the N
. structure, in general, the compositions of zeolite N achievable by the synthesis process can
be described by the formula:
(ML,. P,)i2(Ali,Sle)10O«(Xw, Yd)2 nH2O Where
M = alkali metal or ammonium (e.g. K, Na, NH4); P = alkali metal, ammonium or
metal cations exchanged in lieu of alkali metal or ammonium ion, X = Cl or other
halide and Y = OH, hafide or other anion;
fbrO^a
Therefore the above formula equates to the term "zeolite N structure" as used herein.
As exemplified below, the method of the invention may give rise to potassium-only,
potassium and sodium, potassium and ammonium and potassic high silica forms of zeolite N.
Surprisingly, other forms of zeolite N produced by the disclosed invention include a
potassium-only form with hydroxyl ion as the anion rather than chloride. These compositional
variants have common properties arising from the method of production as described below.
Other compositional variations to the forms described below are possible as will be
appreciated by those skilled in the art.
Zeolites of this invention display a characteristically high proportion of external surface area
(with values greater than 5m2/g),.a distinctive X-ray diffraction pattern as shown in Figures 2,
5 and 6 and a high selectivity to ammonium and certain metal ions in the presence of alkali
metal and alkaline earth ions in solution. In a powder X-ray diffraction pattern, the product of
this process to make zeolite N shows a high background between the region 25°
This high background intensity which ranges between 5% and 15% of the maximum peak
height, may extend beyond 28 = 35° up to 20 = 70°. This high background intensity is not
observed in prior art on hydro-thermally synthesised zeolite N and suggests the presence of
nano-sized crystals and/or amorphous aluminosilicate in association with zeolite N.
Without wishing to be bound by theory, the attributes of zeolite N formed by the process of
this.invention and the proximity of amorphous aluminosilicates (as described in US 6,218,329
5
and US 5,858,081) to zeolite N in the phase diagram shown in Figure 1 suggest that
amorphous aluminosilicate derivatives of kaolin (or of montmorillonite) are an intermediate or
transitory phase in the production of zeolite N by this process and thereby imparts physical
properties that cannot be developed through conventional hydrothermal synthesis.
The disclosed process results in aluminosilicates of zeolite N structure possessing the
following properties:
(a) high selectivity for exchange of ammonium ions (ranging from 75% to 100%) in the
presence of alkali metal and/or alkaline earth ions in aqueous solutions with a wide
range of pH values, especially in comparison to other zeolites with Si:AI ~ 1.0
(b) high selectivity for exchange of metal ions (ranging from 30% to 100 %) such as
copper, cadmium, zinc, nickel, cobalt and lead in the presence of alkali metal and/or
alkaline earth ions in aqueous solutions with a wide range of pH values, especially in
comparison to other zeolites with Si:AI ~ 1.0
(c) BET surface area values greater than 1 m2/g, preferably greater than 5 m2/g and
less than 150m2/g
(d) a high proportion of external surface area to internal surface area especially
compared with other zeolites with SiAl ~ 1.0
(e) capacity to absorb ammonia gas between 0°C and 300°C
(f) absorption capacity for oil ranging from 50g/100g to 150g/100g,
(g) compositions with ratios of silicon to aluminium ranging from 1.0 to 5.0 preferably
from 1.0 to 3.0,
(h) cation exchange capacity ranging from 100meq/100g to 700meq/100g, preferably
greater than 200meq/100g for ammonium ions in solution with concentrations
between less than 1 mg/L to greater than 10,000mg/L,
(i) when in an ammonium-exchanged form, capacity to re-exchange alkali metal ions
from caustic solutions (e.g. NaOH or KOH) ranging in concentration from 0.1 M to
2.0 M, preferably between 0.4 M and 1.5 M
0') removal rate of ammonium ranging between 50 % and 100 %, preferably between
90 % and 100 %, from ammonium-loaded zeolite N using a caustic only regenerant
solution and
(k) capacity to re-exchange ammonium ions and/or retain high selectivity for ammonium
ions after regeneration with a caustic only solution.
Many of these properties, having been disclosed for zeolite N of this invention, may also be
attributable to zeolite N of the prior art or zeolite N formed by other processes. However
properties (c), (d) and (f) are believed to be only applicable to zeolite N of the present
invention.
6
BRIEF DESCRIPTION OF THE DRAWINGS
Reference is now made to non-limiting embodiments of the present invention described by
way of example with reference to the accompanying figures and tables.
Figure 1: Ternary diagram showing formation of zeolite N in relation to sodalite and kaolin
amorphous derivative under similar reaction conditions. The zeolite N phase field is
delineated by solid lines. The region between the dotted line and solid line is the approximate
location for formation of amorphous aluminosilicates.
Figure 2: Typical X-ray powder diffraction pattern for potassium-formed zeolite N (Example
7) with all intensities normalised to \maK -100. All peaks are indexed to the unit cell of zeolite
N in space group I222; key reflections are indicated on the figure.
Figure 3: X-ray powder diffraction pattern for amorphous aluminosilicate as described in
Example 18. Reflections for residual (un-reacted) kaolin are denoted by "K".
Figure 4: Comparison of H2O/AI2O3 ratio and cation ratio for zeolite M (diamonds) and
sodalite (squares) formed by the disclosed process and zeolite N formed by prior art (triangle;
Christensen and Fjelvag, 1997). Mote that the tern perature of formation for zeolite N of prior
artis300°C.
Figure 5: X-ray powder diffraction pattern for zeolite N formed by the method described in
Example 9. Peaks related to minor quartz are denoted "Qfz". Key reflections are indicated on
the figure.
Figure 6: X-ray powder diffraction pattern for zeolite N from Example 10. Key reflections are
indicated on the figure.
Figure 7: Comparative X-ray diffraction patterns for (a) amorphous aluminosilicate, (b)
intermediate stage containing both amorphous aluminosilicate and zeolite N and (c) zeolite N
as noted in detailed description.
Figure 8: Dependence of cation exchange capacity (CEC) with time of reaction for the
method(s) described in Example 1 and Example 2.
Figure 9: Comparative loading capacities for zeolite N (filled symbols), zeolite A (open
squares) and clinoptilolite (open circles) (a) in the presence of calcium ions as described in
Example 22 and (b) fn the presence of sodium ions as described in Example 24.
7
Figure 10: Comparative regeneration capacities for mixtures of NaOH and NaCI used over
three cycles for zeolite N as described in Example 24.
Figure 11: Comparative regeneration capacities for mixtures of NaOH and Na2CO3 for one
regeneration cycle for zeolite N as described in Example 24.
Figure 12: Comparative regeneration capacities for NaOH only at different molarities used
over two cycles for zeolite N as described in Example 24.
Figure 13: Reduction in ammonium ion concentration for a fixed bed of zeolite N and zeolite
A at a flow rate of 4.5 BVhr1 for an ammonium-rich water as described in Example 25.
Figure 14: Reduction in ammonium ion concentration for a fixed bed of zeolite N and zeolite
A at a flow rate of 2.25 BVhr"1 for an ammonium-rich water as described in Example 25.
Figure 15: Reduction in ammonium ion concentration for a fixed bed of zeolite N and
clinoptilolite at a flow rate of 29 BVhr"1 for an ammonium-rich water over two loading cycles
and one regeneration cycle as described in Example 26.
Figure 16: Reduction in ammonium ion concentration for a fixed bed of zeolite N and
clinoptilolite at a flow rate of 2 BVhr'1 for an ammonium-rich water from a anaerobic digester
side stream as described in Example 27.
Figure 17: Reduction in ammonium ion concentration for a fixed bed of zeolite N at a flow
rate of 5 BVhr'1 and 10 BVhr'1 for an ammonium-rich water from a sewage treatment plant as
described in Example 28.
Figure 18: Reduction in ammonium ion concentration for a fixed bed of zeolite N at a flow
rate of 4 BVhr"1 for an ammonium-rich water from a landfill site over two loading cycles and
one regeneration cycle as described in Example 29.
Figure 19: Comparative metal ion selectivity over calcium ions for zeolite N and zeolite A as
described in Example 33.
Figure 20: Reduction in nitrogen leaching from a sandy soil profile for various applications of
zeolite N as described in Example 34. The control (i.e. 0 T/ha) is for no application of zeolite
N and shows typical nitrogen leaching rates for sandy soils when liquid fertilisers are used.
8
DETAILED DESCRIPTION OF THE INVENTION
Zeolite N Synthesis
Table 1 refers to a comparison of reaction conditions for selected zeolites produced by prior
art. Table 1 shows that Barrer etal. (1953) did not produce high yields of zeolite N, but rather,
produced mixtures of kalsilite and zeolite N or leucite and zeolite N. In their work, Barrer et
al. (1953) used high temperatures (450°C), long times (1 -2 days) and high quantities of
water and potassium salt to produce a potassium-only zeolite N. Barrer and Marcilly (1970)
used a stoichiometric amount of KOH and a high excess of KCI but did not produce a zeolite
N from a kaolin starting material. Christensen and Fjellvag (1997) use an excess of KCI with
a sodium aluminosilicate zeolite to produce zeolite N of composition KuAlioSiwO^Cb.SHaO.
In particular, the present invention produces a form of zeolite N which is broader in scope
that that produced by Christensen and Fjellvag (1997) as will be apparent from the foregoing.
The present invention surprisingly produces a form of zeolite N by mechanical mixing of
different reactants, individually or in combination, over a wide range of concentrations at
ambient pressures below 'IOO°C. The present invention offers many starting reactants to
produce many different compositions of zeolite with the N structure. Examples of starting
compositions for specific reaction conditions to produce zeolite N in accordance with the
invention are given in Table 2. Aluminosilicates such as kaolin or montmorilionite are
preferred starting materials for the present invention.
Once the product is formed, additional procedures for manufacture may comprise
i. washing of the zeolite N product to remove excess salts followed by subsequent drying
of the solid product
ii. re-use of the caustic liquor as part of a caustic solution for subsequent production of
additional zeolite N by the same process and
iii. re-use of the washing solution for subsequent production of zeolite N by the same
process.
In contrast, prior art teaches the use of hydrothermal synthesis in a static mixture using an
autoclave to enhance crystallisation from an aluminosilicate gel or zeolite A. Zeolite N of a
specific composition is formed by one specific ratio of reactants in the prior art (Christensen
and Fjellvag, 1997).
In Table 2, specific examples of the present invention (Examples 1,4,5,6,7,9,1 o, 11 and
12) are compared with prior art for production of zeolite N (Christensen and Fjellvag, 1997).
Table 2 shows that reaction parameters by which this synthesis procedure are described
9
such as K2O/AI2O3, KCI/AI2O3, H2O/AI2O3, Na2O/AI2O3) NaCI/A!2O3, CI/SiO2, K/(K+Na) and
(K+Na-AI)/Si (i.e. in their totality), are markedly different from prior art.
Preferred ratios of reagents for the potassic and sodic compositions of zeolite N by the
disclosed process over the temperature range 80°C to 95°C may comprise
(a) K2O/AI2O3 between 0.3 and 15.0,
(b) KCI/AI2O3 between 0.0 and 15.0,
(c) Na2O/Al2O3 between 0.0 and 2.5,
(d) NaCI/AI2O3 between 0.0 and 2.8,
(e) CI/SiO2, between 0.0 and 6.5,
(f) K/(K+Na) between 0.5 and 1.0 and
(g) (K+Na-AI)/Si between 2.0 and 18.0, preferably between 3.0 and 11.0.
Similar ratios of other reagents may also be used under similar circumstances to produce the
appropriate compositional form of zeolite N.
In contrast, Examples 15 and 16 (also summarised in Table 2) show the outcome for
synthesis conditions using the methods of the present invention (i.e. mechanical agitation at
ambient pressure at T
Fjellvag (1997; Example 15) and for similar H2O/AI2O3 ratio used to define the phase diagram
in Figure 1 (Example 16). In both cases, the product is zeolite A rather than zeolite N.
Phase Diagram
Systematic evaluation of reaction variables for a spscific temperature (e.g. 95°C) and water
content (e.g. 48
formation of zeolite N by the present invention may be described by the ratios of reagents in
the mixture. Figure 1 shows a ternary phase diagram for zeolite N production defined by the
major components K, Na and Cl. The data in Figure 1 are for a reaction temperature of 95°C
for 6 hours.
The stability field for zeolite N formation will vary with temperature and water content but over
a range of values will remain substantially as described in Figure 1. For example, at lower
temperature of reaction, the phase field broadens in comparison to that shown in Figure 1.
Evidence for this is given in Example 10 in which the formation of zeolite N occurs at K=1.0 at
a temperature of 90°C. For comparison, the prior art process by Christensen and Fjellvag
(1997) cannot be plotted on this ternary diagram.
As exemplified in Figure 1, other phases may form if the conditions differ from the broad
process of the present invention. For example, if the sodium content in a reaction mix is high,
sodalite may form. Alternatively, potassium-rich phases such as kaltophyllite or kalsilite may
10
form outside the conditions delineated for the present invention. The formation of
aluminosilicate derivatives or kaolin amorphous derivatives - as described in US 6,218,329
and US 5,858,081 (designated "KAD" in the ternary diagram) - may also occur outside the
conditions for formation of zeolite N of this invention.
The relationships between these phases - sodalite, zeolite N and KAD - are demonstrated in
Figure 1. A representative X-ray powder diffraction pattern for zeolite N of the present
Invention is shown in Figure 2 (data for Example 7). Note the relatively high background
intensity (between 5% and 10% of maximum peak height) common to these forms of zeolite
N.
The region between the dotted and solid lines in Figure 1 defines approximately the formation
conditions for materials previously described in US 6,218,329 and US 5,858,081. Example 18
demonstrates that - in comparison to the form of zeolite N of this invention - amorphous
aluminosificates form in that segment of the phase diagram shown in Figure 1 as "KAD". For
reference, an X-ray diffraction pattern of this amorphous aluminosilicate as described in
Example 18 is shown in Figure 3.
Figure 4 is a phase diagram showing H20/Al203 versus cation ratio for the formation of
zeolite N and sodalite for reaction temperature of 95°C and time of six hours. In this figure,
data from the present invention are plotted as diamonds, sodalite as squares and the prior art
from Christensen and Fjellvag (1997) as a triangle. Reaction parameters for zeolite N of the
present invention are significantly different to that of prior art and lies at higher cation ratio
values compared with sodalite. Figure 4 highlights the wide difference in water content
between conventional hydrothermal synthesis and the method described in this disclosure for
zeolite N production.
Zeolite N Structure and Compositions
Zeolite N is classified within the EDI type framework as defined by the international zeolite
association (www.zeolites.ethz.ch/zeolites). The composition of Zeolite N according to the
study by Christensen and Fjellvag (1997) is K12AlioSi1004oCI2.8H20. Compositional variations
on this formula defined by Christensen and Fjellvag (1997) have not been disclosed for
zeolite N in the prior art.
The products of the present Invention include a wide variety of compositions which are
determined by the starting compositions represented, for example, by the phase diagrams
shown in Figures 1 and 4. Another aspect of the invention is the surprising production of
different compositional forms of zeolite N through the procedure of the present invention. The
com positional forms produced by this novel non-hydrothermal synthesis route include those
11
described in Table 3 and thus, extend the suite of zeolite N materials formed by hydrothermal
and non-hydrothermal synthesis routes. Specific examples of synthesis related to each
compositional form are given in Table 3.
An X-ray powder diffraction pattern for zeolite N of the present invention with high Si:AI ratio
derived from montmorillonite (Example 9) is shown in Figure 5. Bulk chemical analysis and
calculation of product stoichiometry suggest that Mg and/or Fe may be incorporated into the
structure. As noted in Table 3, stoichiometric evaluation of bulk chemical analyses for
products of this process suggest the presence of other ions (such as OH and/or NO) within
the zeolite N structure. A form of zeolite N of the present invention in which OH ion replaces
the Cl ion within the structure is given in Example 10. An X-ray powder diffraction pattern for
this zeolite N is shown in Figure 6.
A set of indexed reflections for Examples 9,10 and 11 are compared with indices determined
by Christensen and Fjellvag (1 997) in Table 4. Variations in the intensity of key reflections in
the regions 11.0°
compositional variants compared to the potassium-only form identified by Christensen and
Fjellvag (1997).
X-ray powder diffraction patterns for all examples identified as zeolite N in this description
follow the type patterns shown in Figures 2,5 and 6 and the data shown in Table 4. Materials
produced with these characteristic X-ray diffraction patterns are encompassed within this
invention.
Recycling of Caustic Solution during Synthesis
For the present invention, recycled caustic reagent may be repeatedly used to produce high
yield of zeolite N. The quantity of caustic liquor available for recycling after the initial reaction
is dependent upon the efficiency of solid-liquid separation technique used. The efficiency of
filter pressing, centrifugation or other such separation techniques will be appreciated by
those skilled in the art.
Comparison of the caustic usage for the production of an equivalent mass of zeolite N as a
result of (a) no recycle of caustic and (b) caustic recycle is summarised in Table 5. For
Example 1 and the use of caustic recycle shown in Example 2, the quantity of caustic used
with recycled liquor to produce 783 kg of zeolite N Is reduced to 61 % of the quantity used in
reactions without recycle. The caustic to product ratio is reduced to the values shown in
Table 6 when up to eight times recycle of the liquor is included in the manufacturing process.
A greater or lesser number of recycling steps can be implemented with similar outcome(s) to
that provided in the examples below.
12
Such high proportions of caustic liquor recycle are. not evident for hydrothermal synthesis
methods of zeolites, particularly those with 1
Re-use of the separated caustic liquor after reaction to form zeolite N of this invention is not
limited to potassic forms of caustic reagents or their mixtures inasmuch as sodic or other
suitable forms of caustic reagent, their mixtures (for example, sodium hydroxide and sodium
chloride) and mixtures with potassic or other alkali forms are suitable candidates.
Properties of Zeolite N
A summary of bulk properties for zeolite N of the present invention is shown in Table 6. This
table shows that cell dimensions, bulk composition, cation exchange capacity (CEC) and
BET surface area will vary depending on the starting chemistry of the disclosed process.
However, all properties remain within the broad range of values for each parameter defined
in the claims of this invention. For example, with a higher Si/AI ratio, the CEC value for
Example 9 is lower than achieved for zeolite N formed by the processes described in
Examples 1 and 4. This difference in CEC value Is related to the Si/AI ratio of the resulting
product. In both cases, the CEC value approaches the theoretical limit for an aluminosilicate
of the respective Si:AI ratio.
The ion-exchange behaviour in zeolites is complex and not completely understood
(Weitkamp and Puppe, 1999) and without wishing to be bound by theory, ion-exchange
kinetics and selectivity is related to a combination of factors including zeolite pore size, zeolite
pore shape, the hydrophilicity or hydrophobicity of the zeolite framework and the electrostatic
potential in zeolite channels.
Yet another aspect of this invention is the production of compositional varieties of zeolite N by
room temperature ion-exchange in an aqueous solution, ion-exchanged forms produced from
the present invention Include those described in Table 3.
Element substitution via exchangeable cations in the zeolite N structure of the present
invention include: sodium, ammonium, copper, zinc, nickel, cadmium and silver for
potassium and/or sodium and/or ammonium (Examples 19,20,33 and 35). X-ray diffraction
patterns of these exemplifications demonstrate that zeolite N is formed by the methods
described herein.
The proportion of external or internal exchange sites present in an aluminosilicate framework
influences exchange behaviour in small pore zeolites. Conventional zeolites comprising
micrometre-sized particles typically contain the majority of exchange sites in the internal
13
channels with only a small percentage of the exchange sites present on the external surface.
For example, for a spherical zeolite particle of 1 micron diameter the external surface area is
approximately 3 m2/g whereas the Internal surface area may be 500 mz/g or more. In this
case, the external surface area represents less than 1 % of the internal surface area. This is
generally the case for hydro-thermally synthesised zeolites of small Internal pore size (/.e.
0.38nm) and, it Is speculated, applies to the form of zeolite N of the prior art.
Alternatively, nano-crystalline zeolites contain a much greater fraction of external surface
sites and, for zeolites of small internal pore size, this is reflected In the surface area
measurements determined by conventional BET methods. For example, 100 nm-sized
zeolite particles have an external surface area approximately 30 m2/g.
The small internal pore sizes for zeolite N {ranging from 0.28 to 0.30 nm in effective
diameter) preclude the measurement of internal surface area by conventional adsorption of
nitrogen gas at liquid nitrogen temperatures (the standard BET method) as the kinetic
diameter of nitrogen gas is 0.368 nm. Thus, the surface area for zeolite N measured by the
BET method is the area of the external zeolite surface. The external surface areas for zeolite
N of the present invention are listed for Examples 1 to 20 in Table 6.
The BET surface area for zeolite 4A, a structure also with a small internal pore size, Is less
than 2.5 mz/g. A comparison with products of the present invention shows that in all cases,
the external surface area for zeolite N is greater than hydro-thermally synthesised zeolite 4A.
For zeolite N of the present invention, surface area values are greater than 5m2/g and In
some cases are significantly higher at 55m2/g and 100mz/g. These surface area values imply
that the primary particle size is sub-micrometer in dimension and that the bulk of the products
formed by the disclosed process are nano-crystaliine. Electron microscopy on the products
of the present invention confirms that primary particle sizes range between 50 nm and 500
nm in two dimensions. Zeolite N of the present invention commonly forms laths although
other morphologies are possible.
A possible link between the amorphous aluminosilicate represented by the X-ray diffraction
pattern in Figure 3 and the zeolite N of this invention is summarised by the three patterns
shown in Figure 7. The three X-ray diffraction patterns show (a) amorphous aluminosilicate
as described in Example 18, (b) a combination of amorphous aluminosilicate and minor
amounts of zeolite N of this Invention and (c) zeolite N of this invention as described in
Example 8. Each material in Figure 7 has been prepared by the methodology described in
this invention but with starting compositions that represent three different positions on the
phase diagram in Figure 1.
14
In this figure, residual (un-reacted kaolin) peaks are marked "K". A close relationship
between the key basal spacings of the starting clay (e.g. the (001) reflection of kaolin) and
key peaks (e.g. the (110) reflection) of zeolite N of this invention is apparent. Similarly, the
(002) reflection for kaolin at d~3.57A is closely related to the (220) reflection of zeolite N of
this invention.
While not wishing to be bound by theory, these similarities in d-spacings for key reflections
imply a re-arrangement of atoms within a Si-AI network resulting in key spacings within the
zeolite N structure. In addition, the similarity of structural data implies a transformation to the
zeolite N structure from kaolin (or montmorillonite or other aluminosilicate) via an
intermediate phase which may be the amorphous aluminosilicate described in US 6,218,329
B1 and US 5,858,081 and reproduced in Example 18.
Indirect support for this interpretation is revealed in the higher than expected background
intensity for X-ray powder diffraction patterns when normalised against a calibration standard
such as quartz. With normalisation, background intensities range from 5% to 15% of
maximum peak height in powder X-ray diffraction patterns of zeolite N of the present
invention. In comparison, the diffraction pattern described byChristensen and Fjellvag (1997)
shows background intensity less than 1% of the peak height as is common for hydro-
. thermally crystallised zeolites.
As disclosed in Example 21, the ammonium exchange capacity for zeolite N is higher than
other zeolitic materials. Thus, zeolite N is a suitable material for the removal of ammonium
ions in water or wastewaters. Comparisons of ammonium removal using other zeolites with
Si:AI - 1.0 and with natural zeolites such as clinoptilolite demonstrate that zeolite N Is a
superior material for this purpose.
Examples 22 and 23 show that zeolite N as disclosed In Examples 1 and 19 shows higher
ammonium ion selectivity than zeolite A or clinoptilolite in the presence of a single alkaline
earth or alkali metal ion (e.g. Ca2+ or Na+ as disclosed in Example 22) or mixtures of alkaline
earth ions (e.g. Ca2+ and Mg2* as disclosed in Example 23). Surprisingly, zeolite N has a
much higher selectivity for ammonium in the presence of a high sodium ion concentration
than zeolite A.
Other instances of higher selectivity for ammonium in the presence of many competing ions
(such as potassium, sodium, calcium and magnesium) are described in Examples 27,28,29
and 30. Granulated forms of zeolite N similarly show higher loading capacity and higher
selectivity for ammonium Ions compared with granulated forms of zeolite A or clinoptilolite (as
15
disclosed in Examples 25,26 and 27) over a wide range of ammonium ion concentrations.
Furthermore, Examples 27 and 28 show that zeolite N is an effective material for the removal
of ammonium ion in sewage treatment plants and Example 38 shows that anions may be
absorbed from wastewaters using zeolite N. Data from Example 29 show that zeolite N
removes ammonium from landfill leachate. Examples 24,26 and 29 show that the capacity of
zeolite N for ammonium removal is retained or higher than the first loading cycle after
regeneration using a caustic only solution.
Example 39 shows that zeolite N absorbs oil at capacities greater than other aluminosilicates
such as attapulgite, zeolites X and P and toentonite.
If zeolite N is loaded with ammonium tons, removal of the ammonium species and
regeneration of material can be achieved by re-exchange with a solution comprising alkali
ions such as sodium. However, the use of salt solutions may not be chemically efficient for
many zeolite types and the resultant brine solution can be difficult to dispose or re-use in an
environmentally responsible and cost-effective manner.
Zeolite N of this invention can be regenerated by any of the known means in the prior art and,
as shown in Examples 24, 26 and 29, is amenable to regeneration by means of solutions
comprising only sodium hydroxide. This latter behaviour is in contrast to previously disclosed
literature which advocates the use of sodium chloride based solutions. Furthermore, a 1.2M
NaOH regenerant solution provides high efficiency of ammonium capture when used on
ammonium-loaded zeolite N. In contrast, and as disclosed in Example 26, cfinoptilolile
ammonium removal performance is degraded substantially after regeneration with a 1.2M
NaOH solution.
Zeolite N exchanges with a range of cationic species such as transition metals (including but
not limited to Cu, Zn, Ni, Co) and heavy metals (including but not limited to Cd, Ag and Pb) as
described in Examples 33 and 37. Similar exchange will occur for lanthanides and actinides
with zeolite N of this invention. Zeolite N may be In the form of a powder or as a pellet or
granule. Any soluble salt of the cation to be exchanged with zeolite N can be employed;
examples include metal chlorides, nitrates or sulphates.
This invention relates to use of zeolite N (prepared as disclosed in Example 1) through
exchange with anti-microbiologically active ions such as zinc, copper and silver (as described
in Example 33). The method of preparation of the zeolite N material with antimicrobial ions
can be varied in accord with the following limitations. The identity of the silver, copper or zinc
precursor species is not critically important provided the precursor salt is soluble in water.
16
For instance, nitrate salts are very soluble and easy to use and other salts are available for
use.
Co-exchange of silver and/or copper and/or zinc and/or ammonium ions together with zeolite
N can provide an effective multi-purpose antibacterial material as disclosed in Example 35.
Zeolite N has exceptional capacity for ammonium ions and, without wishing to be bound by
theory, it is proposed that the ammonium ions may help avoid discoloration of the zeolite
when in use. Drying of the co-exchanged material is performed at a temperature less than
400 °C, preferably less than 250 °C and more preferably at a temperature less than 150 °C.
The loading rates for ammonia gas absorption for Zn- and Ag-exchanged zeolite N are
described in Example 37. In these examples, ammonia gas is absorbed in the presence of
water and other gases at temperatures greater than 50°C. The loading of ammonia gas onto
metal-exchanged zeolite N is effective at a range of temperatures from 0°C to 350°C. Data in
Table 13 for Example 37 show that loading rates greater than 30g NH3 per kg of zeolite N can
be achieved at temperatures higher than 80°C for gas streams containing between 8% and
30% water, between 10% and 15% CO2 and 1,000 ppm NH3.
Similarly, proton-exchanged zeolite N of this invention absorbs ammonia gas. Alkali*
exchanged zeolite N is exchanged with a solution of ammonium species until approximately
100 % exchange is achieved. Subsequently, the ammonium-exchanged zeolite N is heated to
decompose the ammonium species to protons without loss of zeolite N structure. A
temperature of 300 °C for a period of at least several minutes is sufficient to decompose the
majority of the ammonium species while minimising the extent of dehydroxylation and
maximising the formation of proton-exchanged zeolite N.
If zeolite N Is loaded with adsorbed ammonia gas, a means of regeneration is by thermal
swing desorption. This regeneration involves heating ammonia-loaded zeolite N material in
an atmosphere such as air or inert gas to a temperature sufficient to desorb the ammonia.
The temperature required for desorption depends upon the identity of the exchangeable ion
on the zeolite N framework and can be found by techniques such as, but not limited to,
temperature programmed desorption (TPD), differential thermal analysis (DTA) or
thermogravimetric analysis (TGA).
Preparation of surfactant modified zeolite N can be achieved by any of the known methods in
the prior art. The basic principle involves contacting zeolite N with an aqueous solution of the
surfactant species for sufficient time to obtain optimum exchange of the surface sites on the
zeolite. Quaternary amine salts are species of choice and examples of these compounds
include hexadecyltrimethylammonium (HDTMA), benzyltrirnethylarnmonium chloride (BTMA),
17
tetraethylammonium bromide (TEA), benzyldimethyltetradecylammonium (BDTMA), tert-butyl
ammonium bromide, hexadecylpyridinium (HDPY), tetramethylammonium (TMA),
trimethylphenylammonium (TMPA) and dioctodecyldimethyiammonium (DODMA). Naturally,
there exist many other suitable surfactants to modify the surface of the zeolite N material.
The present invention relating to the process to make zeolite N offers the following
advantages:
1. high yields of zeolite N (achieves >90%) in large volume production
2. temperature of reaction is low (i.e.
3. volumes of solution required are low
4. feed liquor can be supplemented by recycled liquor from a previous batch of zeolite
N production and
5. feed liquor can be supplemented by recycled wash water from a previous batch of
zeolite N production.
Zeolite N made by the process of the present invention provides the following advantages:
1. a hydrophilic material with excellent selectivity for ammonium ion exchange in
the presence of alkali metal and alkaline earth ions compared with existing
aluminosilicates
2. a hydrophilic material with exceptional capacity to exchange ammonium ions
from solutions compared with other existing aluminosilicates
3. capacity to be formed into granules suited to fixed bed exchange columns for
ion exchange of alkali metal, alkaline earth, ammonium, transition metal, rare
earth and actinide metal ions
4. capacity for continuous re-use through cyclic regeneration of the material (as
granules and/or as powders) using a caustic only solution such as NaOH or
KOH or mixtures thereof
5. improved capacity to remove ammonium ion from solutions compared with
existing aluminosilicates such as zeolites 4A, clinoptilolite and bentonite
6. improved capacity to remove metal ions from solutions compared with existing
aluminosilicates such as zeolites 4A, clinoptiiolite, bentonite and kaolinite
7. improved capacity to absorb oil compared with existing aluminosilicates such as
zeolites 4A, X, P, bentonite and kaolinite
8. capacity to co-exchange alkali metal, metal and/or ammonium ions to form a
selectively exchangeable material useful for agricultural, antibacterial and other
applications
9. capacity to exchange metal, ammonium or hydronium ions for adsorption of
ammonia gas
10. capacity to exchange metal, ammonium or hydronium ions for adsorption of
18
ammonia gas from gas flows which contain water
11. capacity to adsorb complex compounds to impart a hydrophobic character
12. capacity to capture anions from solution.
While the invention has been described in connection with a preferred embodiment, it is not
intended to limit the scope of the invention to the particular form setforth, but on the contrary,
it is intended to cover such alternatives, modifications, and equivalents as maybe included
within the spirit and scope of the invention as defined by the appended claims.
STANDARD PROCEDURES
For zeolite N reactions at bench and pilot plant scale, stainless steel reactors equipped with
(i) a mixing blade, (Ii) an external heating coil with thermocouple and (iii) a loose-fitting.cover
have been employed. For many reactions at scales > 600 g, samples of the mix are
extracted during the reaction in order to measure standard parameters. Measurements of
pH for these reaction mixtures are obtained from samples held between 60°C and 65°C.
Methods for characterisation of solid products include X-ray powder diffraction, surface area
analysis, bulk elemental analysis and cation exchange capacity for ammonium ion. X-ray
data were collected on a Bruker automated powder diffractometer using CuKct radiation
(X=1.5406) between 5° and 70° 20 at a scan speed of 1° 28 per minute using quartz as a
calibration standard. The International Centre for Diffraction Data files were used to identify
major phases in all samples. Cell dimensions for zeolite N samples were obtained by least-
squares refinement from X-ray powder diffraction patterns. Least-squares refinements on
cell dimensions require a two-theta tolerance of ±0.1° (i.e. difference between observed and
calculated reflections) for convergence.
Surface area measurements were obtained on a Micrometrics Tri-Star 3000 instrument using
the BET algorithm for data reduction and standard procedures for adsorption and desorption
of nitrogen. Bulk elemental analyses for major elements were obtained by inductively coupled
plasma spectroscopy (ICP) using standard peak resolution methods.
Cation exchange capacities were determined experimentally for equilibrium exchange of
ammonium ion in a 1M NH4CI solution. The procedure for determination of experimental CEC
values described in this work is as follows:
0.5 g of the material is dispersed into 25 ml of RO water and centrifuged at 3,000 rpm for 10
minutes. After decanting the supernatant for measurement of potassium ions, 30 ml of 1M
NH4CI is added in solution to the samples, shaken to disperse particles and allowed to agitate
19
for a period of 16 hours. The equilibrated solution is then centrifuged at 3,000 rpm for 10
minutes and the supernatant solution discarded. Yet again, 30 ml of 1M NH4CI solution is
added and the solids dispersed by shaking and agitated for two hours. Repeat this process
for ammonium exchange a further time. Following the third centrifuge event 30 ml of
absolute ethanol is added to wash the sample, mixed and then centrifuged for 10 minutes.
The ethanol wash process is repeated using an additional 30 ml of absolute ethanol a further
two times. Subsequently, 30 ml of 1M KCI solution is added to the samples and agitated for
a period of 16 hours. The samples are then centrifuged for 10 minutes and the supernatant
decanted into a clean 100 mL volumetric flask. Again, 30 ml of 1M KCI solution is added to
the solid sample, shaken and agitated for two hours. Repeat centrifuge, decant into clean
100 mL flasks, add KCI solution and agitate a further two times. Make up each of the
volumetric flasks with decanted supernatant to 100 ml with 1M KCI solution. Finally, all
samples are analysed for ammonium ion concentration using the method by Kjeldahl (steam
distillation). The cation exchange capacity for each sample is then calculated from these
data.
This method for CEC determination when used on a well-known clay material (Cheto
montmorfllonite, AZ, Clay Minerals Society Source Clays SAz-1; van Olphen and Fripiat,
1979) as an internal calibration standard gives a CEC value of 98.1 ± 2.5 meq/100g (54
analyses over a period of eighteen months). This value is consistent with the value for
potassium exchange on SAz-1 of 100 + 2 meq/100g determined by Jaynes and Bingham
(1986). If not identified to the contrary, CEC values determined for the material(s)
exemplified in this work are on a "wet weight" basis {i.e. no correction for dry weight of the
material). CEC values determined on a dry weight basis use the same protocol as given
above but with samples dried at 105°C overnight prior to dispersion in water for
measurement of potassium ions.
For applications of zeolite N in practice, it may be necessary to granulate the powder into a
form which is amenable for use in, for example, a fixed bed configuration in a column. The
granulation process includes mixing zeolite powder with a suitable binder material,
subsequent forming into a viable shape such as a spherical or elongate granule and then
calcining the material to impart physical strength. Those skilled in the art will be aware of
many methods and approaches to form granules of zeolitic material. The identity of the
binder is not particularly limited and common materials such as clays, polymers and oxides
may be used. For example, sodium silicate ("water glass") addition at levels up to 20 % is an
effective means to produce granules with suitable mechanical properties. It is desirable to
use the least amount of binder suited to the purpose so that the cation exchange capacity of
zeolite granules is maximised. Calcination of zeolite N is preferably carried out at
temperatures below 600°C and it is more preferable to calcine at temperatures less than
20
550°C.
The success of ion exchange methods in a fixed bed depends upon a range of engineering
criteria which should be considered when using zeolite N. The size distribution of zeolite
granules and the bulk density have an impact upon trie effective ammonium ion exchange
capacity (Hedstrom, 2001). In addition, hydraulic residence time (or flow rate) and inlet water
composition (e.g. pH, TDS, ammonium ion concentration) influence the outcome of fixed bed
exchange reactions. In the comparative examples used for this disclosure, similar sized
granules (typical range between 1.6mm and 2.5mm) and similar operating conditions have
been used in order to provide clear evidence for the superior performance of zeolite N for
wastewater treatment.
The test for linseed oil absorption is described as follows: 5g of material is kneaded by hand
on a glass plate using a spatula with boiled linseed oil. The linseed oil is added drop-wise
from a burette and the amount required to achieve the end point is measured. The end point
is determined as the point at which the 5g of material is completely saturated with oil and has
a consistency of putty. The volume of oil required to achieve the end point is converted to
weight of oil per weight of material (I.e. g/100g).
EXAMPLES AND ILLUSTRATIVE EMBODIMENT
Example 1: Production of zeolite N with KOH and KCI.
75kg of 98% solid potassium hydroxide (Redox Chemicals, caustic potash Capota45, QLD
Australia), 75kg of 98% solid potassium chloride (Redox Chemicals, POCHLO16, QLD
Australia) and 250 litres of water supplied by a conventional domestic reticulated system are
placed in a 500L stainless steel reactor tank. This caustic solution is stirred and heated to
95°C. While the solution is at this temperature, 75kg of kaolin (Kingwhite 65, supplied by
Unimin Pty Ltd, Kingaroy, QLD Australia) is added to the reaction mix while stirring the
solution. The reaction mix experiences a slight drop in temperature (to ~90°C) during the
loading of kaolin. Depending on the quality of heating process employed, the reaction mixture
may show temperature fluctuations of up to 5°C without significant loss of product quality.
Small quantities of solid materials (approximately 50g) from the reaction mix are sampled at
half-hourly intervals during this reaction and are characterised by conventional methods.
The reaction tank is partially covered with a stainless steel lid to aid with retention of heat and
vapour(s). The reaction tank is maintained at ambient pressure during the production
process. The pH of this reaction mix is generally greater than 14.0 and during the course of
the reaction may reduce to approximately 13.5. During the reaction process -approximately
21
1.5 hours to 3.5 hours after the kaolin has been added to the reactor - the viscosity of the
mixture increases. Addition of small amounts of water at this time to aid mixing of the slurry
may be undertaken though it is not necessary to achieve production of zeolite N.
After 6.0 hours of reactant mixing at temperatures 95°C ± 5°C, the reaction is stopped by
reduction of the temperature to less than 50°C via cooling coils, addition of water or both
methods and the resulting slurry is separated using a filter press into solid and liquid
components. The solid aluminosilicate - zeolite N - is washed with water and then dried
using conventional drying methods (such as a spray dryer) to form the final product with
properties listed in Table 6. The weight of zeolite N from this reaction is 98.3kg which
represents a volume yield of greater than 90% for the reaction.
Characterisation of the material using standard methods such as X-ray diffraction, bulk
chemical analysis, surface area analysis and cation exchange capacity will be known to those
skilled in the art.
Example 2: Recycle of mixed caustic liquor from Example 1 reaction.
120kg of the liquor containing both KOH and KCI and any un-reacted kaolin from the process
described in Example 1 is retained for transfer back to the reaction tank. The reaction tank is
topped up with 254kg of caustic (comprising 59.1kg of KOH, 54.2kg of KCI and 141.4L of
water) and pre-heated to 95°C. 75kg of kaolin is added to the caustic liquor, mixed thoroughly
for 6.0 hours while maintaining the reaction temperature at 95°C ± 5°C. After 6.0 hours, the
reaction tank is cooled to less than 50cC and the resulting slurry is separated into solid and
liquid components using a filter press. The solid is washed with water and then dried using
conventional drying methods (such as a spray dryer) to form the final product with properties
listed in Table 6.
The same procedure given above is repeated for the next seven reactions using appropriate
masses of caustic recycle and caustic make-up for each run. The properties of the resultant
zeolite N from selected batch reactions using recycled liquor are listed in Table 6. Figure 8
shows cation exchange capacities determined for each zeolite N batch produced by the
recycling of caustic liquor and the evolution of CEC values as each reaction proceeds to
completion.
Example 3: Variation of process for zeolite N production - time and method of reaction.
75kg of 98% solid potassium hydroxide, 75kg of 98% solid potassium chloride, 250 litres of
water supplied by a conventional domestic reticulated system and 75kg of kaolin are placed
22
in a 500L stainless steel reactor tank. This reaction mix or viscous slurry is stirred and heated
to 95°C over a period of seven hours. Once the slurry is at 95°C, the reaction is maintained at
95°C ± 3°C for a further nine hours and then cooled to less than 50°C to stop the reaction.
The resulting slurry is separated using a filter press into solid and liquid components. The
solid aluminosilicate - zeolite N - is washed with water and then dried using conventional
drying methods (such as a spray dryer) to form the final product with properties listed in Table
6.
Example 4: Variation of process for zeolite N production - KOH with other chloride salt.
75kg of 98% solid potassium hydroxide, 30kg of 98% solid sodium chloride (Cheetham Salt,
Superfine grade, Australia), and 180 litres of water supplied by a conventional domestic
reticulated system are placed in a 500L stainless steel reactor tank. This caustic solution is
stirred and heated to 95°C. While the solution is at this temperature, 60kg of kaolin is added
to the reaction mix while stirring the solution.
After 6 hours of mixing at temperatures 95°C + 5°C, the reaction is stopped by reduction of
the temperature to less than 50°C via cooling coils, addition of water or both methods and the
resulting slurry is separated using a filter press into solid and liquid components. The solid
aluminosilicate - zeolite N - is washed with water and then dried using conventional drying
methods (such as a spray dryer) to form the final product with properties listed In Table 6.
Example 5: Variation on zeolite N process - KOH with two chloride salts.
600g of 98% solid potassium hydroxide, 1,500g of solid potassium chloride, 350g of 98%
solid sodium chloride, and 2.21 litres of water supplied by a conventional domestic reticulated
system are placed in a 5L stainless steel reactor tank. This caustic solution is stirred and
heated to 95°C. While the solution is at this temperature, 550g of kaolin are added to the
reaction mix while stirring the solution.
The reaction is undertaken substantially as described in Example 1 for a period of 6 hours at
95°C. The solid aluminosilicate - zeolite N - is washed with water and then dried using
conventional drying methods (such as a spray dryer) to form the final product with properties
listed in Table 6.
Example 6: Formation of zeolite N with potassium hydroxide, sodium hydroxide and chloride
salts.
488g of 98% solid potassium hydroxide, 373g of solid potassium chloride, 100g of solid
23
sodium hydroxide (Redox Chemicals, QLD Australia), 125g of 98% solid sodium chloride,
and 2.21 litres of water supplied by a conventional domestic reticulated system are placed in
a 5L stainless steel reactor tank. This caustic solution is stirred and heated to 95°C. While
the solution is at this temperature, 660g of kaolin are added to the reaction mix while stirring
the solution.
The reaction is undertaken substantially as described in Example 1 for a period of 6 hours at
95°C. The solid aluminosilicate - zeolite N - is washed with water and then dried using
conventional drying methods (such as a spray dryer) to form the final product with properties
listed in Table 6.
Example 7: Formation of zeolite N using liquid potassium silicate and other salts
660g of 98% solid potassium hydroxide, 660g of 98% solid potassium chloride, 150g of liquid
potassium silicate (Kasil 30, supplied by PQ Corporation, Melbourne Australia) and 2.21 L of
water supplied by a conventional domestic reticulated system are placed in a 5L stainless
steel reactor tank. This caustic solution is stirred and heated to 95°C. While the solution is at
this temperature, 660g of kaolin are added to the reaction mix while stirring the solution.
The reaction is undertaken substantially as described in Example 1 for a period of 6 hours at
95°C. The solid aluminosilicate - zeolite N - is washed with water and then dried using
conventional drying methods (such as a spray dryer) to form the final product with properties
listed in Table 6. The powder X-ray diffraction pattern for this example is shown in Figure 2.
Example 8: Formation of zeolite N using potassium silicate and zeolite N seed
660g of 98% solid potassium hydroxide, 660gof 98% solid potassium chloride, 450g of liquid
potassium silicate (Kasil 30, supplied by PQ Corporation, Melbourne Australia), 2.21 L of
water supplied by a conventional domestic reticulated system and 180g of zeolite N formed
by the process in Example 1 are placed in a 5L stainless steel reactor tank. This caustic
solution is stirred and heated to 95°C. While the solution Is at this temperature, 660g of kaolin
are added to the reaction mix while stirring the solution.
The reaction is undertaken substantially as described in Example 1 fora period of 6 hours at
95°C. The solid aluminosilicate - zeolite N - is washed with water and then dried using
conventional drying methods (such as a spray dryer) to form the final product with properties
listed in Table 6. Indexed reflections for X-ray powder diffraction of this sample are listed in
Table 4. Note that this form of zeolite N has a Si:AI ratio higher than material formed in
Examples 1, 2 and 4.
24
Example 9: Formation of zeolite N using a 2:1 clay
1,150g of 98% solid potassium hydroxide, 850g of 98% solid potassium chloride and 1.6L of
water supplied by a conventional domestic reticulated system are placed in a 5L stainless
steel reactor tank. This caustic solution is stirred and heated to 95°C. While the solution is at
this temperature, 660g of montmorillonlte (Activebond 23, supplied by Unimin Pty Ltd,
Australia) are added to the reaction mix while stirring the solution.
The reaction is undertaken substantially as described in Example 1 fora period of 10 hours
at 95°C. The solid aluminosilicate- zeolite N - is washed with water and then dried using
conventional drying methods (such as a spray dryer) to form the final product with properties
listed in Table 6. The powder X-ray diffraction pattern for this example is shown in Figure 5.
Note that this form of zeolite N has a Si:Al ratio higher than that material formed from kaolin
(see Examples, 1, 2 and 4) and a resultant lower CEC value determined using standard
procedures.
Example 10: Formation of zeolite N without chloride ion
1,650g of 98% solid potassium hydroxide and 0.9L of waier supplied by a conventional
domestic reticulated system are placed in a 5L stainless steel reactor tank. This caustic
solution is stirred and heated to 90°C. While the solution is atthis temperature, 330g of kaolin
are added to the reaction mix while stirring the solution.
The reaction is undertaken substantially as described in Example 1 fora period of 12 hours
at 90°C. The solid aluminosilicate - zeolite N - is washed with water and then dried using
conventional drying methods (such as a spray dryer) to form the final product with properties
listed in Table 6. An X-ray diffraction pattern for this zeolite N product is shown in Figure 6.
indexed reflections for this product are provided in Table 4.
Example 11: Formation of zeolite N using ammonium salt and caustic
660g of 97% ammonium chloride (Redox Chemicals, QLD Australia) is added to 1.93L of
water in a 5L stainless steel reactor tank. A further 1,200g of 98% solid potassium hydroxide
is slowly added to this mixture. The caustic solution is stirred and heated to 95°C. While the
solution is at this temperature, 600g of kaolin are added to the reaction mix while stirring the
solution.
The reaction is undertaken substantially as described in Example 1 for a period of 6 hours at
25
95°C. The solid aluminosilicate - zeolite N - is washed with water and then dried using
conventional drying methods (such as a spray dryer) to form the final product with properties
listed in Table 6. Indexed reflections for X-ray powder diffraction of this sample are listed in
Table 4.
Example 12: Formation of zeolite N at lower temperature and higher water content
1,880g of 98% solid potassium hydroxide, 1,31 Og of 98% solid potassium chloride, 3.0 litres
of water supplied by a conventional domestic reticulated system and 375g of kaolin are
placed in a 5L stainless steel reactor tank. This reaction mix or viscous slurry is stirred and
heated to 80°C over a period of twelve hours and then cooled to less than 50°C to stop the
reaction. The resulting slurry is separated using a filter into solid and liquid components. The
solid aluminosilicate - zeolite N - is washed with water and then dried using conventional
drying methods (such as a spray dryer) to form the final product with properties listed in Table
6.
Example 13: Formation of zeolite N with KOH and a sodic salt
660g of 98% solid potassium hydroxide, 150g of 98% solid sodium chloride and 2.21 L of
water are placed in a 5L stainless steel reactor tank. This caustic solution is stirred and
heated to 95°C. While the solution is at this temperature, 660g of kaolin are added to the
reaction mix while stirring the solution.
The reaction is undertaken substantially as described in Example 1 for a period of 6 hours at
95°C. The solid aluminosilicate - zeolite N - is washed with water and then dried using
conventional drying methods (such as a spray dryer) to form the final product with properties
listed in Table 6.
Example 14: Comparative synthesis with insufficient potassium or chloride.
120g of 98% solid potassium hydroxide, 400g of 98% solid potassium chloride, 350g of solid
sodium hydroxide and 2.21 litres of water are placed in a 5L stainless steel reactor tank. This
caustic solution is stirred and heated to 95°C. While the solution is at this temperature, 660g
of kaolin are added to the reaction mix while stirring the solution.
The reaction is undertaken substantially as described in Example 1 for a period of 6 hours at
95°C. The solid aluminosilicate is washed with water and then dried using conventional drying
methods (such as a spray dryer) and characterised using standard methods such as X-ray
diffraction, bulk chemical analysis, surface area analysis and cation exchange capacity. X-ray
26
diffraction of this sample shows that the zeolite N phase does not form. The X-ray data show
that the crystalline phase is sodalite with minor amounts of amorphous aluminosilicate
material.
Example 15: Comparative synthesis using Christensen and FjellvSg (1997) reactant ratios
The reagents used by Christensen and FJellvag (1997) are combined in the same ratios and
subjected to process conditions described in this patent application. 660g of 98% solid
potassium chloride is combined with 2.6L of water and placed in a 500L stainless steel
reactor tank. This solution is stirred and heated to 95°C. While the solution is at this
temperature, 264g of zeolite 4A (supplied by PQ Corporation, VIC Australia) are added to the
reaction mix while stirring the solution.
The reaction is undertaken substantially as described in Example 1 for a period of 6 hours at
95°C. The solid aluminosilicate is washed with water and then dried using conventional drying
methods (such as a spray dryer) and characterised using standard methods such as X-ray
diffraction and cation exchange capacity. X-ray diffraction of this sample shows that the
zeolite N phase does not form. The X-ray data show that the crystalline phase is zeolite 4A.
Example 16: Comparative synthesis using Christensen and Fjeilva'g (1997) reactant ratios
and lower water content
The reagents - zeolite 4A and potassium chloride - used by Christensen and Fjellvag (1997)
are combined in the same ratios and subjected to process conditions described in this patent
application at the same ratio of H2O/AI2O3 as used in Example 1. 660g of 98% solid
potassium chloride is combined with 0.6L of water and placed in a 500L stainless steel
reactor tank. This solution is stirred and heated to 95°C. While the solution is at this
temperature, 264g of zeolite 4A (supplied by PQ Corporation, VIC Australia) are added to the
reaction mix while stirring the solution.
The reaction is undertaken substantially as described in Example 1 fora period of 6 hours at
95°C. The solid aluminosificate is washed with water and then dried using conventional drying
methods (such as a spray dryer) and characterised using standard methods such as X-ray
diffraction and cation exchange capacity. X-ray diffraction of this sample shows that the
zeolite N phase does not form. The X-ray data show that the crystalline phase is zeolite 4A.
Example 17: Comparative synthesis without chforide ion at higher temperature.
1,650g of 98% solid potassium hydroxide and 0.9L of water supplied by a conventional
27
domestic reticulated system are placed in a 5L stainless steel reactor tank. This caustic
solution Is stirred and heated to 95°C. While the solution Is at this temperature, 330g of kaolin
are added to the reaction mix while stirring the solution. The ratio of reactants in the starting
mixture is the same as described in Example 10.
The reaction is undertaken substantially as described in Example 1 fora period of 24 hours
at 95°C. Sampling of the reaction mix at 6 hours and 12 hours indicated the formation of
kaliophyllite only. The solid aluminosilicate is washed with water and then dried using
conventional drying methods (such as a spray dryer) and characterised using standard
methods such as X-ray diffraction and cation exchange capacity. X-ray diffraction of this
sample shows that zeolite N does not form. The X-ray data show that the crystalline phase is
kaliophyllite.
Example 18: Comparative synthesis with insufficient chloride from two salts.
660g of 98% solid potassium hydroxide, 100g of solid potassium chloride and 75g of solid
sodium chloride is placed with 2.21L of water in a 5L stainless steel reactor tank. This caustic
solution is stirred and heated to 95°C. While the solution is at this temperature, 660g of kaolin
are added to the reaction mix while stirring the solution.
The reaction is undertaken substantially as described in Example 1 for a period of 6 hours at
95°C. The solid aluminosilicate is washed with water and then dried using conventional drying
methods (such as a spray dryer) and characterised using standard methods such as X-ray
diffraction and cation exchange capacity.
An X-ray diffraction pattern of this sample (Figure 3) shows that zeolite N does not form. The
X-ray data show that the resultant material is kaolin amorphous derivative as previously
described in US 6,218,329 B1, US 6,218,329 B2 and US 5,858,081.
Example 19: Exchange of potassium zeolite N to sodium zeolite N form.
20kg of zeolite N formed by the process described in Example 1 are placed in a stainless
steel reaction tank and thoroughly mixed with 2M NaOH solution for two hours at room
temperature (~25°C). The solid and liquid are separated via conventional means (e.g. a filter
press or by sedimentation/decanting). The solid is washed thoroughly in water and then dried
by conventional means (e.g. spray dryer). The solid shows partial exchange of potassium
Ions for sodium ions and the properties listed in Table 6. X-ray powder diffraction confirms
the sodium exchange form is zeolite N. Further exchange of potassium and sodium ions in
zeolite N is effected by additional exchanges of the type described in this example.
28
Example 20: Exchange of potassium zeolite N to ammonium zeolite N.
20kg of zeolite N formed by the process described in Example 3 are placed in a stainless
steel reaction tank and thoroughly mixed with 5M NH4NO3 solution held at 70°C for two
hours. The solid and liquid are separated via conventional means (e.g. a filter press or by
sedimentation/decanting), the solid is washed thoroughly in water and then subjected to a
second exchange using 5M NH4NO3 solution held at 70°C for two hours. The solid is washed
thoroughly in water and dried by conventional means (e.g. spray dryer). The solid shows
exchange of potassium Ions for ammonium ions and the properties listed in Table 6. X-ray
diffraction shows the phase has zeolite N structure. Almost complete exchange of potassium
ion is demonstrated by the bulk analysis (K2O=2.0 wt%) and high value for loss-on-ignition
determination (LOI=23.4 wt%).
Example 21; Comparative Cation Exchange Capacities for Ammonium Ions on a mass
and volume basis
Zeolite 4A (PQ Corporation), Clinoptilolite (Australian Zeolites), montmorillonite (Activebond
23) and kaolinite (Kingwhite 65; Unimin Australia Pty Ltd) are compared with zeolite N
prepared by methods as disclosed in Examples 1.
Cation exchange capacities are determined experimentally for equilibrium exchange of
ammonium ion as described in the Standard Procedures. Table 7 shows that the highest
ammonium ion CEC value, by mass or volume, is for zeolite N described in this invention.
Zeolite A also exhibits good capacity for ammonium ions in accord with a low Si/AI ratio.
However, as shown beiowzeolite A does not satisfy commercial criteria such as ammonium
ion selectivity.
Example 22: Selectivity of Zeolite N for Ammonium Ions in the Presence of Alkaline Earth
or Alkali Metal Ions Compared to Zeolite A and Clinoptilolite
Zeolite N, zeolite A and clinoptilolite are compared in this example. Amounts of 0.2 g of
zeolite material are placed in 200 mL of aqueous solutions of ammonium ions (prepared from
ammonium chloride) and constantly agitated for a period of 2 hours at ambient temperature.
To evaluate the selectivity of zeolites N, A and clinoptilolite in the presence of alkaline ions,
different amounts of calcium ions (prepared from calcium chloride precursor) are added to
the ammonium ion solution. Figure 9a shows the effect of calcium ion concentration upon
the ammonium loading of zeolites N, A and Clinoptilolite when a constant ammonium ion
29
concentration of 50 mg/L is present in the solution.
The capacity for ammonium ion uptake by zeolite N is not significantly influenced by
concentrations of competing calcium ions up to 200 mg/L. In contrast, the capacity for
ammonium ion uptake by zeolite A in the presence of competing calcium ions is significantly
reduced. For example, the loading of ammonium ions changes from 23.5 g/kg when no
calcium ions are present to 7.1 g/kg when 200 mg/L calcium ions are present. The
ammonium loading for zeolite A in the presence of high calcium concentration is similar to
that for clinoptilofite. Clinoptilolite shows low capacity for ammonium ions under all testing
conditions.
To evaluate the selectivity of zeolites N, A and clinoptilolite in the presence of alkali metal
ions, different amounts of sodium ions are added to the ammonium ion solution. Figure 9b
shows the effect of sodium ion concentration upon the ammonium loading of zeolites N, A
and Clinoptilofite when a constant ammonium ion concentration of 50 mg/L is present in the
solution.
The capacity for ammonium ion uptake by zeolite N is not significantly influenced by
concentrations of competing sodium ions up to 400 mg/L. Surprisingly, the capacity for
ammonium ion uptake by zeolite A in the presence of competing sodium ions is significantly
reduced. For example, the loading of ammonium ions changes from 23.5 g/kg when no
sodium ions are present to 8.7 g/kg when 400 mg/L sodium ions are present. Clinoptilolite
shows low capacity for ammonium ions under all testing conditions.
Example 23: Comparative selectivity for ammonium ion in aqueous solutions with Ca2* and
Mg2*ions.
Zeolite 4A (PQ Corporation) and clinoptilolite (Australian Zeolites) are compared with zeolite
N prepared by methods disclosed in Examples 1 and 19. Approximately 0.2 g of zeolite
material is equilibrated at room temperature for 1 hour with 200mL of an aqueous solution
comprising ammonium, calcium and magnesium ions at the concentrations indicated in Table
8. The comparative results determined as equivalent cation exchange capacities for each
zeolite in each solution are tabulated in Table 9.
Table 9 shows that both forms of zeolite N are characterized by a high loading capacity for
ammonium ions in the presence of calcium and magnesium ions. In contrast, zeolite A is not
selective towards ammonium ions in the presence of calcium and magnesium ions.
Furthermore, the data for clinoptilolite shows that calcium and magnesium ion concentration
30
actually increases when this material is added to the test solution. The CEC value for
clinoptilolite for ammonium ions is considerably lower than the value recorded for zeolite N.
For solutions containing 1,000 mg/L ammonium Ions, the loading values for ammonium ion
are 444 meq/100g and 451 meq/100g forzeolite N (Examples 1 and 19), respectively, when
50 mg/L calcium ions are present and 475 meq/100g and 434 meq/100g for zeolite N,
respectively, when 120 mg/L calcium ions are present. Consequently, zeolite N is an
excellent material for ammonium ion exchange capacity and ammonium ion selectivity for a
wide range of ammonium and alkaline earth ion concentrations.
In contrast, the performance of zeolite 4A is detrimentally affected by the presence of
additional calcium ions in solution. For solutions containing 1,000 mg/L ammonium ions, the
loading value for zeolite 4A is 261meq/100g when 50mg/L calcium ions are present and
192meq/100g when 120 mg/L calcium ions are present. This represents a drop of over 25%
in the performance of zeolite 4A in the presence of competing Ca and Mg ions.
Clinoptilolite did not show any appreciable exchange for ammonium in the presence of
calcium and magnesium ions with an increased concentration of calcium ions to 120 mg/L.
However, the loading value for ammonium ions is low under all conditions (over 4 times lower
than for zeolite U). Clinoptilolite does not offer properties suited to commercial treatment of
wastewaters for removal of ammonium ions in the presence of Ca*2 and Mg+2.
Example 24: Regeneration of ammonium-loaded Zeolite N
A series of caustic solutions have been compared for regeneration of an ammonium-loaded
zeolite N. The regenerant solution compositions include industrial grade NaOH (only), NaOH
and NaCI, NaOH and Na2CO3 in a range of concentrations. Ammonium loading of zeolite N
on each cycle is with 1M NH4CI solution.
For regeneration cycles, 20g of ammonium loaded zeolite N is contacted with 80ml of
regenerant solution in a 250mL Nalgene bottle with constant shaking for two hours. The
solution is centrifuged at 3,000rpm forfive minutes and the amount of ammonium and pH of
the supernatant is measured. For second and subsequent regenerations, the same
procedure is used on re-loaded ammonium zeolite N. The removal rate of ammonium ton for
each regenerant solution is determined by measurement of ammonium in the regenerant
solution and on the solid sample before regeneration.
Figures 10 and 11 show the effective ammonium removal rate as a percentage of total
ammonium on the material for solutions with different ratios of NaOH+NaCI and
31
NaOH+Na2CO3. The data in Figures 10 and 11 show thatfor both combinations of solutions
as a regenerant, removal of ammonium can be achieved at all ratios of NaCI or Na2CO3 to
NaOH. This outcome is consistent with teachings from prior art.
However, for zeolite N of the present invention, a higher removal rate (I.e. > 75%) for
ammonium ion occurs for ratios in which NaOH is present at concentrations equivalent to or
more than 0.4M. Furthermore, these data show that the highest removal rate occurs for
NaOH only solutions. Thus, ammonium-loaded zeolite N is suited to regeneration by NaOH
solutions held at high pH (I.e. greater than 12) without degradation of the material.
The range of NaOH concentrations for which an effective removal rate can be achieved from
ammonium-loaded zeolite N is shown in Figure 12. At low molarify (0.1 M), the removal rate is
low at 40%. However, at higher molarity and, specifically above 0.4M NaOH, the removal rate
is greater than 85% for the first regeneration and higher for the second regeneration. In this
instance, the form of zeolite N is potassic for the first cycle of loading/regeneration and sodic
for the second cycle of loading/regeneration. For subsequent regenerations, removal rates of
>90% are maintained when the molarity is > 0.4M.
This comparison of regeneration solutions shows that ammonium-loaded zeolite N is ideally
suited to regeneration by sodium-rich solutions and, in particular, by NaOH solutions with
molarity greater than 0.4. This result is in contrast to that of Breck (US 3,723,308) who
showed that a saturated lime solution with sodium chloride and calcium chloride is a suitable
regeneration solution for zeolite F and Sherman and Ross (US 4,344,851) who used 1 .ON
NaCI with NaOH (adjusted to pH '12.0) to regenerate zeolites W and F. The data in Figure 10
show that for NaCI/NaOH solutions with pH - 12.0 at high NaCI molarity. the ammonium
removal rate is significantly less than a NaOH only solution (i.e. 32% vs 84% on first cycle;
62% vs 94% on second cycle).
Example 25: Comparative example of ammonium exchange by Zeolite N and Zeolite A in
a fixed bed column
Granules of test material(s) are loaded into glass columns (~52mm; packed bed height
~750mm) with inlet and outlet openings suited to flow of test solutions and analysis of
samples. The configuration of column arrangements for fixed bed treatment and the
determination of bed volume for each material type are known to those skilled in the art. A
synthetic solution (pH = 7.25) containing 1,020 mg/L NH/ is introduced to the columns via
variable speed pumps at flow rates ranging from 1.2 l/hr to 10.5 l/hr. The solutions are
pumped in a down-flow direction for ammonia loading and in an up-flow direction during
regeneration. Use of regenerant solution(s) for ammonium-loaded zeolite N is described in
32
Example 24.
The concentration of ammonium ion in the outflow after pumping through the column and the
volume of solution treated is measured. Test solutions are pumped at a constant bed volume
flow of 4.5 bed volumes per hour or 2.25 bed volumes per hour for each test sample. In each
case, a similar mass of zeolite material is used in each column.
Comparative data for ammonium exchange of zeolite N (as described in Example 1) and
zeolite A are shown in Figures 13 and 14 for the two different flow rates. In both cases, the
"breakthrough" point - for this experiment taken as 50mg/L ammonium concentration in the
treated water - is achieved after a much longer period of time (or volume of water treated) by
zeolite N than by zeolite A. For example, In Figure 13 breakthrough is achieved by zeolite A
after 12 bed volumes while zeolite N achieves breakthrough after 100 bed volumes. Data in
Figure 14 show that zeolite A achieves breakthrough in 14 bed volumes while zeolite N has
not reached breakthrough after 120 bed volumes. Those skilled in the art will recognise that
the performance of zeolite N under these conditions is superior to that of zeolite A.
Example 26: Comparative ammonium exchange by Zeolite N and Clinoptilolite in a fixed
bed column
Granules of test material(s) are loaded into glass columns ((j>~52mm; packed bed height
~750mm) with inlet and outlet openings suited to flow of test solutions and analysis of
samples as noted in Example 25. A synthetic solution (pH = 7.6) containing 30 mg/L MH4+ is
introduced to the columns and the concentration of ammonium ion in the outflow after
pumping through the column and the volume of solution treated is measured. Test solutions
are pumped at a constant flow of 28 bed volumes per hour for each test sample. In each
case, a similar mass of zeolite material is used in each column. For this test, clinoptilolite is
pre-treated by the methods described in Komarowski and Yu (1997) to optimise ammonium
loading capacity.
Comparative data for ammonium exchange of zeolite N (as described in Example 1) and
clinoptilolite are shown in Figure 15. Two cycles of loading are represented for each zeolite
tested. Each zeolite is regenerated after the first loading using 1.2M NaOH solution as
described in Example 24.
The "breakthrough" point for this experiment is 5 mg/L ammonium concentration in the
treated water. Clinoptilolite shows capacity to remove ammonium from the synthetic solution
for approximately 5 bed volumes In the first loading cycle, but does not achieve ammonium
levels below 5mg/L in the treated solution on the second loading cycle.
33
In contrast, zeolite N of the present invention reduces ammonium levels to well-below
breakthrough for at least 3,000 bed volumes in the first loading cycle and for more than 3,750
bed volumes in the second loading cycle after regeneration.
Loading capacity for each zeolite can be determined by simple measurement of ammonium
in the regenerant solution or by integration of ammonium concentration for a full loading cycle
{i.e. to a point where outlet ammonium concentration is
concentration). Using these methods, the loading capacity for clinoptilolite in this example is
2.3 g NlV per kg of zeolite. This value is consistent with data previously obtained by
Komarowski and Yu (1997) for clinoptilolite. For zeolite N, the loading capacity is 65 g NH4+
per kg of zeolite.
Example 27: Comparative ammonium exchange by zeolite N and clinoptilolite in wastewater
solution containing multiple divalent and univalent ions.
Granules of test materials) are loaded into glass columns (
~750mm) with inlet and outlet openings suited to flow of test solutions and analysis of
samples as noted in Example 25. Wastewater at pH 8.0 produced by an anaerobic digester
side stream in a sewage treatment plant is introduced into the columns after a sand filtration
step to remove suspended solids. Solutions are pumped at a constant flow rate of 2 bed
volumes per hour for each test material. The mass of test material in all columns is
equivalent for zeolite N and clinoptilolite. The digester side stream wastewater shows typical
concentrations for Ca2+ and Mg2+ (43 mg/L and 13 mg/L, respectively), Na+ and lC(320 mg/L
and 230 mg/L, respectively) as well as high levels of alkalinity, BOO, COD and total dissolved
solids (4,500 mg/L, 94 mg/L, 1,300 mg/L and 2,100 mg/L, respectively). The inlet ammonium
ion concentration is 1,528 mg/L.
Comparative data for ammonium exchange using zeolite N (as described in Example 1) and
clinoptilolite are shown in Figure 16. For these experiments, a breakthrough point of 35 mg/L
ammonium ion is achieved by zeolite N after more than 50 bed volumes are treated. In
comparison, the same mass of clinoptilolite does not achieve an outflow concentration less
than 35 mg/L under the same operating conditions. Clinoptilolite only reduces the outflow
ammonium ion concentration to -130 mg/L in the first loading cycle shown in Figure 16.
The poor performance of clinoptilolite In this instance is not only due to a low cation exchange
capacity, but also due to poor selectivity for ammonium ions in the presence of Ca2+, Mgz+,
Na+ and K+. However, zeolite N clearly removes ammonium ion from digester side stream
which contains competing ions such as Ca2+, Mg2+, Na+ and K* and trace levels of transition
34
metals (e.g. Cu2*, Zn2+ and Fe2+).
Example 28: Ammonium ion removal from primary fbw at a sewage treatment plant.
Granules of test material are loaded into glass columns (~52mm; packed bed height
~750mm) with inlet and outlet openings suited to flow of test solutions and analysis of
samples as noted in Exam pie 25. Wastewater at pH ~7.0 collected from the exit of a primary
ciarifier in a large sewage treatment plant is introduced into the columns without a pre-
filtration step to remove suspended solids. Solutions are pumped at constant flow rates of 5
bed volumes per hour and 10 bed volumes per hour. The wastewater shows a typical primary
treated sewage composition for Ca2+ and Mg2+ (30 mg/L and 22 mg/L, respectively), Na+ and
K*(160 mg/L and 18 mg/L, respectively) as well as typical levels of alkalinity, BOD, COD,
suspended solids and total dissolved solids (560 mg/L, 87 mg/L, 100 mg/L, 54 mg/L and 628
mg/L, respectively). The inlet ammonium ion concentration Is 44 mg/L.
Data on the removal of ammonium ion using these exchange columns at two flow rates are
shown in Figure 17. Figure 17 shows that for a breakthrough point of 1 mg/L ammonium ions,
zeolite N is an excellent medium for removal of ammonium at high flow rates. At 10BV/hr
(equivalent to a hydraulic residence time of 6 minutes), zeolite N reduces outflow ammonium
concentrations to less than 1mg/L for more than 650 bed volumes. At lower flow rates (e.g.
5BV/h), ammonium ion concentrations in the treated water remain well below breakthrough
after 1,200 bed volumes. Those skilled in the art will recognise that improved performance of
zeolite N for ammonium ion removal will be achieved with pre-filtration of the inlet column
flow.
Example 29: Ammonium ion removal from landfill leachate by Zeolite N.
Granules of test material are loaded into glass columns (~52mm; packed bed height
~750mm) with inlet and outlet openings suited to flow of test solutions and analysis of
samples as noted in Example 25. Wastewater at pH ~ 8.2 collected from a landfill is
introduced into the columns without a pre-filtration step to remove suspended solids. The
leachate is pumped at a constant flow rate of 4 bed volumes per hour. The leachate shows
concentrations typical for a mature landfill with Ca2+ and Mg2+ (62 mg/L and 38 mg/L,
respectively), Na* and K* (1,100 mg/L and 340 mg/L, respectively) as well as typical levels of
alkalinity, suspended solids and total dissolved solids (2,200 mg/L, 18 mg/L and 3,700 mg/L,
respectively). The inlet ammonium ion concentration is 205 mg/L.
Data for two successive loadings of ammonium onto the pre-treated zeolite N fixed bed
35
columns are shown in Figure 18. Regeneration of the ammonium-loaded zeolite N using
1.2M NaOH solution only follows the methods outlined in Example 24, For this wastewater,
the concentration of sodium and potassium ions is many times the concentration of
ammonium ions (a factor of ~6 times). However, data in Figure 18 show clearly that
ammonium ion concentration is reduced to less than 1 mg/L in the treated outflow for many
bed volumes (e.g. greater than 230 bed volumes at 4 BV/h). Furthermore, the ammonium
loading capacity after regeneration of zeolite N granules is equivalent to, or better than, the
ammonium loading capacity on the first cycle.
Example 30: Use of Zeolite N for ammonium ion removal from an aqueous solution in the
presence of calcium, potassium and sodium ions at typical levels for ruminal fluid.
Zeolite 4A and clinoptilolite are compared with zeolite N as described in Examples 1 and 19.
An amount of 0.2 g of zeolite material is equilibrated at room temperature for 1 hour with 200
mL of an aqueous solution comprising 1,000 mg/L ammonium, 100 mg/L calcium, 2,000
mg/L potassium and 2,000 mg/L sodium ions. Results on treatment of this solution with
zeolite A, zeolite N and clinoptilolite are shown in Table 10.
The data in Table 10 reveal that zeolite N is characterized by a high loading capacity for
ammonium ions in the presence of calcium, sodium arid potassium ions (a positive value for
loading shows that ions are adsorbed by the material of interest, whereas a negative value
shows that ions are released into the solution by the material of interest). In contrast, zeolite
4A, with a theoretical high loading for ammonium ions, was found to be non-selective towards
ammonium ions in the presence of calcium, sodium and potassium ions. Furthermore, the
data for clinoptilolite is unusual in that calcium and magnesium ion concentration actually
increases when this material is added to the tested aqueous solution. For clinoptilolite, the
CEC value for ammonium ions is considerably lower than the value recorded for zeolite N.
The percentage selectivity for ammonium, for example, is defined as:
% selectivity = (CECNH4+ /CEC(ot of zeolite)x100 (1)
where total CEC|Ot = CEC for calcium + CEC for ammonium + CEC for sodium (+/- CEC for
potassium) and CECNH4+.= CEC for ammonium ion. The choice of sodium or potassium ions
in equation (1) depends upon which of these ions is adsorbed by the material of interest.
Table 10 also shows data for the excess ions in solution. This value is calculated from the
measured concentrations of ions in solution'after the material of interest has been added.
The low value for excess ions in all cases indicates that ion exchange (rather than
precipitation of insoluble phases) occurs under these experimental conditions.
36
The values presented in Table 10 clearly show the higher selectivity of zeolite N for
ammonium over alkali metal and alkaline earth ions compared to zeolite 4A and clinoptilolite.
This selectivity is a critical property for commercial application for ammonia concentration
control in ruminant animals.
Example 31: Use of Zeolite Nasa Component of Pet Utter
The effectiveness of zeolite N for reduction of odours associated with ammonia from cat litter
is evaluated at six professional veterinary practices. Approximately 10 % of conventional cat
fitter is substituted with zeolite N granules and the modified litter is placed in animal cages
following standard procedure at each veterinary practice. Subjective responses from staff
regarding the degree of odour reduction are then compiled. In all cases, zeolite N is
considered to successfully reduce ammonia odours. Animals - specifically cats - are not
detrimentally affected by its use.
Example 32: Use of Zeolite N in aquaria to maintain low ammonium concentrations
Zeolite N is applied to separate aquaria (fresh or saline water) for ten different fish species to
reduce ammonium ion accumulation due to natural causes. The zeolite is presented in
several different configurations: either located (i) in an air driven corner filter, (ii) in a nylon
mesh bag in the filter, or (Hi) in a floating nylon mesh bag. Each aquarium contained between
3 and 300 fish, depending on the species. For each aquarium, water ranged between pH 7.0
and 7.2. Zeolite N is held in the aquaria for periods ranging from 12 weeks to 48 weeks
without detrimental impact on the fish. During this time, the ammonium levels in all aquaria
remained below 0.2 mg/L
Example 33: Comparative exchange for copper, zinc, nickel, cobalt, cadmium or lead ion
from an aqueous solution in the presence of calcium Ions.
Zeolite 4A (PQ Corporation) and clinoptilolite (Australian Zeolites) are compared with zeolite
N as disclosed in Examples 1 (a potassium form) and 19 (sodium-potassium form).
Approximately 0.2 g of zeolite material was equilibrated at room temperature for 1 hour with
200 mL of an aqueous solution comprising 50 mg/L of the appropriate metal ion (e.g. copper,
zinc, nickel, cobalt, cadmium or lead) and 200 mg/L calcium ions. The relative cation
loadings for each zeolite on each solution containing a metal ion with calcium ions are given
in Table 11. Percentage selectivity for the specific metal ion is also summarised in Table 11.
Table 11 reveals that, for example, zeolite N is characterized by a high loading capacity for
copper ions in the presence of calcium ions (a positive value for loading shows that ions are
adsorbed by the material of interest, whereas a negative value shows that Ions are released
37
into the solution by the material of interest). Similarly, zeolite 4A shows a comparable value
for loading capacity for copper ions. Clinoptilolite is a very poor material for exchange of
copper ions from aqueous solution.
However, the calcium ion uptake for each zeolite varies significantly. Zeolite 4A exchanges
large quantities of calcium ions and clinoptilolite loads fewer calcium ions. For both zeolite A
and clinoptilolite, the calcium ion uptake is approximately twice the amount of ammonium ion
uptake. However, the performance of zeolite N which exhibits the lowest exchange of calcium
ions in the presence of copper ions shows that the material has the highest selectivity for
small-sized metal ions such as copper. Table 11 compares the copper selectivity values for
zeolite N relative to zeolite 4A and clinoptilolite. The data in Table 11 show that zeolite N is
highly selective towards copper ion in the presence of excess amounts of competing calcium
ions in solution.
Similar data are obtained for the zinc/calcium, nickel/calcium, cobalt/calcium,
cadmium/calcium and lead/calcium systems and are shown in Table 11. The values for
cadmium loading onto zeolite N are lower than for copper ion loading, but again, the
selectivity of zeolite N for cadmium ions over calcium ions is high (> 80%) as shown in Table
11. These selectivity values for cadmium are significantly higher than the value for zeolite 4A.
The selectivity value for clinoptilolite - whilst 100% - has little practical value as the loading
capacity is extremely poor (
Table 11 lists data for nickel and shows that zeolite N of Example 1 is lower in loading
capacity than zeolite N of Example 19 but both are significantly higher than zeolite 4A. The
selectivity for nickel ions over calcium ions is significantly higher for zeolite N than for zeolite
4A or clinoptilolite. Similarly, the selectivity of zeolite N for cobalt and lead is higher that the
selectivity determined for zeolite A or clinoptilolite. A summary of the selectivity data for these
metal ions against calcium is shown in Figure 19 for the zeolites used in this example.
Table 11 also shows the excess ions in solution for each metal/alkali ion system. This value
is calculated from the measured concentrations of ions in solution after the material of
interest has been added. The low value for excess ions in all cases indicates that ion
exchange (rather than precipitation of insoluble phases) occurs under these experimental
conditions. While not wishing to be bound by theory, similarly high selectivity for other metal
ions such as silver over calcium Ions is anticipated for zeolite N.
Example 34: Reduced nitrogen leaching with zeolite Nasa soil supplement
A sandy soil is thoroughly mixed with zeolite N (prepared as disclosed in Example 1 at the
38
• rate 0,1,2,4 and 8 g/kg. The soil mixtures are packed into columns and treated with water
obtained from a natural underground bore. The leading 20 ml of water treatment is fertilised
with ammonium sulphate fertiliser at the rate of 25 mg N per kg of soil. A flow rate of 10
millilitres per min is maintained through the soil column. Samples of leachate are collected in
10 mL vials and analysed for ammonium and total nitrogen content. Data on analysed
nitrogen in the leachate samples are plotted in Figure 20 for pore volumes treated (i.e.
equivalent to volume flow of bore water).
In Figure 20, the control sample, in which no zeolite N is mixed with the soil column,
demonstrates typical nitrogen leachate rates for sandy soils. For example, within one pore
volume of solution treatment, more than 50% of the available nitrogen is leached from the
column. However, with addition of zeolite N in the soil mixture, nitrogen leaching is reduced
significantly. At one pore volume, less than 5% of the available nitrogen has leached from
the column. At four pore volumes with the lowest zeolite N application rate, less than 10% of
the nitrogen has leached from the column.
Example 35: Antimicrobial activity of zeolite N
Zeolite N prepared according to the method disclosed in Example 1 is co-exchanged with
zinc, silver and ammonium ion. A co-exchanged version of zeolite A is also prepared for
comparison with zeolite N. Zeolites co-exchanged with silver, zinc and ammonium ions are
prepared as follows: 0.1 kg of zeolite is mixed with 375 mL of an aqueous solution
comprising 0.05 M silver nitrate, 0.454 M zinc nitrate and 0.374 M ammonium nitrate salts.
Following addition of water to make a total volume of 1000 mL of solution, the sample is
stirred and heated at approximately 50°C overnight After filtering and drying at 110°C, the
exchanged zeolite sample contained 2 wt % silver, 11 wt % Zn and 2.5 wt % ammonium.
A bacterial cell suspension of approximately 106 cells is made up in 100 mL of sterile, distilled
water in a sterile flask. 100 mg of antimicrobial zeolite powder is added to the test
suspensions. The control sample is a 100 mL bacterial suspension of ca. 106 cells without
the presence of antimicrobial zeolite material. Three separate strains of bacteria are
prepared for evaluation: ACM 1900 Escherichia coli, ACM 5201 Pseudomonas aeruginosa
and ACM 1901 Staphylococcus aureus. E. coli and P. aeruginosa are common gram
negative strains while S. aureus is gram positive.
The flasks are placed on a shaker at 150 rpm in an incubation room at 28°C under light
conditions. At contact times of 0,4 and 24 h, 1 mL of culture are taken and serial dilution is
performed. The dilutions are plated on spread plates of PYEA in order to determine the
bacterial concentration. Viable counts of bacteria are performed after the plates are
39
incubated at 37°C overnight.
Results of the plate counts for each bacterial strain are listed in Table 12. Plate counts show
that 100% of the three bacterial strains are destroyed at 4 hours contact and at 24 hours
contact for both zeolite N and zeolite A.
Example 36: Comparative uptake of alkaline earth Ions in the presence of active
antimicrobial ion-exchanged zeolites.
Silver-exchanged zeolite N and zeolite A for comparison are prepared by the following
procedure. 20 g of zeolite is added to a 5 L beaker containing 1.5 L of water. 33.97 g of silver
nitrate is dissolved in 0.5 L of water and then added to the beaker containing the zeolite
slurry. After 2 hours stirring at ambient temperature, the solution is decanted and the zeolite
powder dried at 110°C.
Silver-exchanged zeolites are then contacted with an aqueous solution containing 100 mg/L
calcium ions and 20 mg/L magnesium ions to determine the degree of alkaline earth ion
uptake by the exchanged zeolite. The test solution is made by adding appropriate amounts of
calcium chloride and magnesium sulphate salts to deionized water. 0.2 g of zeolite is then
added to 200 ml_ of the alkaline earth test solution for a period of 1 hour at ambient
temperature. Atomic Adsorption Spectroscopy (AAS) is employed to measure the
concentration of calcium and magnesium ions in solution both before and after contact with
the silver zeolite material. The amount of calcium or magnesium ion exchanged in terms of
millimotes is then calculated from the measured concentrations. The uptake of Ca and Mg
ions (as meq/100g of zeolite) for zeolite N and zeolite A is 47 g/kg and 348 g/kg, respectively.
These CEC values show that Ca and Mg ions are readily exchanged by zeolite A - as
previously described and known in prior art. The low uptake for Ca and Mg ions
demonstrated by zeolite N suggests that silver ion is released to the test solution in a more
controlled manner com pared with zeolite A. Extensive re-use applications of Ag-exchanged
zeolite A may result in loss of antimicrobial activity more rapidly than Ag-exchanged zeolite N.
Example 37: Ammonia gas adsorption using zeolite N
Silver-exchanged zeolite N is prepared by the following procedure: 20 g of zeolite is added to
a 5 L beaker containing 1.5 L of water. 33.97 g of silver nitrate is dissolved in 0.5 L of water
and then added to the beaker containing the zeolite slurry. After 2 hours of stirring at ambient
temperature the solution is decanted and the zeolite dried at 110°C.
40
Zinc-exchanged zeolite N is prepared as follows: 500 mL of 0.454M zinc nitrate solution is
mixed with 50 g of zeolite N, stirred and heated at 50°C for a period of 5 hours. After
decanting the solution, a second exchange is performed with fresh zinc nitrate solution.
Finally, the zinc-exchanged zeolite N is washed and dried at 110GC.
Approximately 0.25g samples of silver-exchanged and zinc-exchanged zeolite N (zeolite Ag-
N and zeolite Zn-N) are placed in a temperature-controlled reactor vessel and subjected to
air flows of composition listed in Table 13 using mass-flow controllers. The space velocity
maintained for all experiments is 50,000 hr'1. The reactor vessel is subjected to a controlled
heating and cooling sequence to measure the adsorption of ammonia gas over a fixed period
of two hours at two operating temperatures - 80°C and 120°C. The ammonia gas content on
the adsorbers is measured by distiliative removal of ammonia species. Data for ammonia gas
adsorption at 80°C and 120°C are provided in Table 13.
Example 38: Absorption ofanions from wastewater using zeolite N
Granules of test materials) are loaded into glass columns (~52mm; packed bed height
~750mm) with inlet and outlet openings suited to flow of test solutions and analysis of
samples as noted in Example 25. Wastewater at pH 8.0 produced by an anaerobic digester
side stream circuit in a sewage treatment plant Is introduced into the columns after a sand
filtration step to remove suspended solids. Solutions are pumped at a constant flow rate of 2
bed volumes per hour for each test material. The digester side stream wastewater shows
typical concentrations for Caz+ and Mg2+ (43 mg/L and 13 mg/L, respectively), Na+ and l
(320 mg/L and 230 mg/L, respectively) as well as high levels of ammonium, alkalinity, BOO,
COD and total dissolved solids (1,528 mg/L, 4,500 mg/L, 94 mg/L, 1,300 mg/L and 2,100
mg/L, respectively). The inlet phosphate ion concentration is 265 mg/L.
Data for this exam pie are listed in Table 14 for treatment of the wastewater at 5 bed volumes
and at 50 bed volumes of flow, respectively. Table 14 shows that total phosphorus is reduced
from 230mg/L to 120mg/L and 190mg/L, respectively at 5 bed volumes and 50 bed volumes
of treated wastewater. Under these conditions, which include many competing ions, reduction
of iron, manganese and zinc also occurs as shown in Table 14.
Example 39: Comparative oil absorption
Samples of zeolite N (Examples 1 r 4,7-11,13 and 20) are subjected to a standard linseed oil
absorption test and compared with the following commercially available materials: (a)
Alumina Hydrate (AS303 supplied by Commercial Minerals Ltd.), (b) Activebond 23
Bentonite (supplied by Commercial Minerals Ltd); (c) Zeolite 4A (supplied by PQ
41
Corporation),
Kingaroy kaolin (Kingwhite 65, Unimin Aust.Ry Ltd), (f) attapulgite (Clay Minerals Society
Source Clays: PF1-1 from Gadsen County FL). The results of these standard oil absorption
tests on zeolite N samples from Examples 1,4, 7 to 11,13 and 20 as well as commercially
available materials are shown in Table 15.
Table 15 shows that zeolite N has high oil absorption capacity and significantly higher values
than bentonites and zeolite 4A. Oil absorption capacity for zeolite N is better than that for
zeolite X (for which property this material Is used in detergents) or zeolite A and, is similar to,
or better than that for attapulgite, bentonife, kaolin and alumina hydrate.
42
Table 1
Comparison of reaction conditions for selected zeolites produced by prior art
Parameter Barrer era/. (1953) Barrer and Marcilly
(1970) Barrer &
Munday
(1971)
Batch
Composition
Material Type analcime gel Na-X kaolin kaolin
SiO2/A!2O3 4 4 2.5 2 2
K2O/AI2O3 0 0.78 0 1 19.9
NaaO/AfeOs 1 0 1 0 0
H20/AI203 88 >68 284 103 378
Kd/AlzOa 12 Not defined 67 24.4 0
NaCI/AlsOa 0 0 0 0 0
Temperature (°C) 450 450 260 >200 80
Time (days) 2 1 4 4 12
Mass of Materials
Batch Melhod(s) Static; autoclave Static; autoclave Static;
autoclave Static;
autoclave Static; autoclave
Product Leuclte +Zeolite N Kalsilite + Zeolite N Zeolite F kaliophilite Zeolite F
43
44
Table 3
Compositional forms of Zeolite N c disclosed in the examples
M** . N** Si:AI X** Y**
Example 1 K - 1.0 Cl -
Example 4 K Na 1.1 Cl -
Example 6 K Na 1.1 Cl (OH)*
Example 8 K - 1.2 Cl -
Example S K (Fe.Mgf 2.4 Cl (OHf
Example 10 K - 1.0 - OH
Example 11 K NH4 1.0 Cl
Example 19 K Na 1.0 Cl (NO)*
Example 20 NH4 K 1.0 Cl (NO)*
Example 33 K Cu 1.0 Cl -
Example 33 K Zn 1.0 Cl -
Example 33 K Ni 1.0 Cl -
Example 33 K Co 1.0 Cl -
Example 33 K Cd 1.0 Cl -
Example 35 l
Example 37 Na Ag 1.0 Cl (NO)*
Example 37 K Zn 1.0 Cl (IMOf
'Inferred by stoichiometry
** refer to general formula for zeolite N
45
Table 4
Comparison of hkl, 28 (obs) and Intensity for X-ray Diffraction patterns from selected examples
Indices Zeolite N
•■ Example 8 Zeolite N
Example 10 Zeolite N
■ Example 11 Christensen &
Fjellvag
2Theta 2Theta 2Theta 2Theta
H K L (Obs) Ihkl (Obs) Ihkl (Obs) Ihkl (Obs) Ihkl
1 0 1 11.20 6 11.19 24
0 1 1 11.24 5 11.19 24
1 1 0 12.64 44 12.59 48 12.70 49 12.64 87
0 0 2 13.54 11 13.54 11 13.58 13 13.52 24
0 2 0 17.92 5
1 1 2 18.54 5 18.46 10 18.53 9 18.55 8
2 1 1 21.12 11 21.17 10
1 2 1 21.21 7 21.23 12 21.22 13 21.17 10
1 0 3 22.24 4 22.24 11 22.25 3
0 2 2 22.64 3 22.64 9
2 2 0 25.47 36 25.41 19 25.48 33 25.44 44
0 0 4 27.23 24 27.16 20 27.30 19 27.23 26
3 0 1 27.70 16 27.90 3
0 3 1 27.92 7 28.04 17 27.90 3
3 1 0 28.44 40 28.38 35 28.52 36
1 3 0 28.58 42 28.52 36
2 1 3 28.65 68 28.70 27
2 2 2 28.95 97 28.92 100 28.98 83 28.92 100
1 1 4 30.13 82 30.00 77 30.20 100 30.12 77
1 3 2 31.72 100 31.68 78 31.75 71 31.65 98
2 0 4 32.63 16 32.80 19
0 2 4 32.85 18 32.90 16 32.80 19
2 3 1 33.39 27 33.37 21 33.38 27 33.34 35
3 0 3 33.84 14
0 3 3 34.11 6 34.18 18
1 0 5 35.45 9 35.44 5
0 1 5 35.53 17 35.44 5
4 0 0 36.13 12 36.07 15
0 4 0 36.54 11
2 2 4 37.68 7 37.62 17 37.61 3
4 1 1 38.08 7 38.02 12 37.89 15 38.06 3
3 3 0 38.56 18 38.50 20 38.57 1
3 2 3 38.67 9 38.72 4
0 4 2 38.95 7 39.10 11 38.92 3
3 1 4 39.71 24 39.84 14
1 3 4 39.90 21 39.85 23 39.84 14
1 2 5 39.98 26 39.99 11
4 2 0 40.52 14
2 4 0 40.86 6 40.79 13
3 3 2 41.12 10 41.06 14 40.99 15 41.05 5
0 0 6 41.32 9 41.33 13 41.33 12 41.35 3
4 1 3 42.95 15 42.95 18 42.95 12
4 2 2 42.95 16
2 4 2 43.15 14 43.22 17 43.22 18
1 1 6 43.49 7 43.42 15 43,11 3
3 0 5 44.03 12 44.11 2
0 3 5 44.16 5 44.16 15 44.11 2
2 0 6 45.38 13
4 0 4 45.92 12 45.85 16 45.98 6
0 4 4 46.01 11 45.98 14 45.98 6
46
Table 5
Comparison of caustic use with and without recycling
Reactant Masses Without
Recycle With Recycle
Mass of kaolin (kg) 675 675
Mass of caustic (kg) 1,350 821
Mass of zeolite N (kg) 783 783
Caustic:Product ratio 1.7 1.05
47
48
Table 7
Comparison of aluminosilicate properties
Property Kaolin Montmorillonite Clinoptilotite Zeolite 4A Zeolite N
(Example 1)
SfcAl 1.09 3.64 4.5 1.0 1.03
CEC+(meq/100g) 19 64 110 472 528
CEC*(meq/L) un un 1.331 2,832 4,224
Surface area (mJ/g) 15.2 78 11.5 2.3 10.7
+CEC values determined for 1M NH4CI equilibrium exchange as described under "Standard Procedures"
un ~ unavailable,
"value determined on granule density.
Table 8
Solution compositions for Example 23
Ammonium ion
concentration
(ma/D . Calcium ion
concentration
(mg/L) Magnesium ion
concentration
(mg/L)
Solution 1 30 50 20
Solution 2 200 50 20
Solution 3 1000 50 20
Solution 4 30 120 20
Solution 5 200 120 ' 20
Solution 6 1000 120 20
Table 9
Loading data for calcium, magnesium and ammonium ions on zeolites described In Example 23
Solution 1 Solution 2 Solution 3 Solution 4 Solution 5 Solution 6
Ca2* Loading (meq/100 g)
Zeolite N (Example 1) 10 25 18 16 32 28
Zeolite N (Example 19) 23 20 9 25 29 16
Zeolite 4A 229 236 206 423 379 297
Clinoptilolite -17 -4 -15 -9 -1 -6
Mg2* Loading (meq/100 g)
Zeolite N (Example 1) 4 0 0 3 1 0
Zeolite N (Example 19) 5 0 0 5 0 0
Zeolite 4A 37 22 7 10 4 -1
Clinoptilolite 2 0 -4 4 1 -6
NH4* Loading (meq/100 g)
Zeolite N (Example 1) 104 347 444 104 331 475
Zeolite N (Example 19) 118 406 451 119 326 434
Zeolite 4A 68 172 261 34 112 192
Clinoptilolite 8 76 71 8 54 115
49
Table 10
Ammonium selectivity of zeolites in alkali-rich solution (Example 30)
Zeolite N
(Example 1) Zeolite N
(Example 19) Zeolite 4A Clinoptilolite
NH4(meq/100g)
Ca (meq/100g) 128
5 155
10 74
24 5
-15
Na (meq/100g)
K (meq/100g) 15
-160 -117
-53 -209
98 9
12
Excess Ions -12 -5 -13 11
% Selectivity (NhM 87 94 38 0
50
Table 11
Metal ion selectivity of zeolites in presence of Ca (Example 33)
Zeolite N
(Example 1) . Zeolite N
(Example 19 Zeolite 4A Clinoptilolite
Copper/Calcium
Loading Cu (meq/100g)
Loading Ca (meq/100g) 115
22 127
35 145
290 4
8
Total Adsorbed Ions
Total Released Ions
Excess Ions 137
-133
4 162
-167
-5 435
-493
-58 12
-9
3
% Selectivity (Cu) 84 79 33 32
Zinc/Calcium
Loading Zn (meq/100g)
Loading Ca (meq/100g) 73
18 82
22 121
269 3
13
Total Adsorbed Ions
Total Released Ions
Excess Ions 91
-107
-16 . 104
-142
-38 390
-457
-67 16
-30
-14
% Selectivity (Zn) 80 79 31 18
Cadmium/Calcium
Loading Cd (meq/100g)
Loading Ca (meq/100g) 45
10 63
13 81
385 1
0
Adsorbed Ions
Released Ions
Excess Ions 55
-76
-21 76
-104
-28 466
-496
-30 1
-6
-5
% Selectivity (Cd) 81 83 17 100
Michel/Calcium
Loading Ni (meq/100g)
Loading Ca (meq/100g) 35
28 62
35 8
456 4
0
Adsorbed Ions
Released Ions
Excess Ions 63
-74
-11 97
-113
-16 464
-487
-23 4
-6
-2
% Selectivity (Ni) 56 64 2 100
Cobalt/Calcium
Loading Co (meq/100g)
Loading Ca (meq/100g) 32
26 54
40 .17
440 7
6
Adsorbed Ions
Released Ions
Excess Ions 58
-77
-19 90
-134
-44 457
•494
-37 13
-24
-11
% Selectivity (Co) 55 57 4 52
Lead/Calcium
Loading Pb (meq/100g)
Loading Ca (meq/100g) 48
100 49
120 48
497 12
83
Adsorbed Ions
Released Ions
Excess Ions 148
-92
56 160
-114
46 545
■499
46 95
-12
83
% Selectivity (Pb) 33 29 9 12
51
Table 12
Comparison of Antibactericidal Activity for Zeolite N and Zeolite A
Bacterial Strain . Four hour Exposure Twenty-four hour Exposure
Zeolite N Zeolite A Zeolite N Zeolite A
E. coli 100 100 100 100
P. aeruginosa 100 100 100 100
S. aureus 99.98 100 99.996 100
Table 13
Gas adsorption behaviour for zeolite N
Material Adsorption
Temperature
TO Ammonia
Loading
(g/kg)
Ag-Zeolite N1 80 66.9
Zn-Zeolite N2 80 30.3
Zn-Zeolite N3 120 37.8
Notes for Table 14:
1. Gas composition; 1000 ppm NH3,15 % CO* 10 % N& 30 % H2O &44.9 % H2
2. Gas composition: 1000 ppm NH3,2000 ppm NO, 9.9 % CO* 6 % HjO & 71.4 % N2
3. Gas composition: 1000 ppm NH3,10 % H;O & 89.9 % N2
Table 14
Reduction of total phosphorus and other ions from wastewater
Property Raw Side
stream Treated Side
stream
(5BV) Treated Side
stream
(50BV)
pH 8.0 9.8 8.9
Suspended solids (mg/L) 360 72 88
Total Phosphorus (mg/L) 230 120 190
Fe (mg/L) 4.1 0.6 0.72
Mn (mg/L) 0.16 0.03 0.03
Zn (mg/L) 0.44 0.07 0.07
52
Table 15
Comparative oil absorption capacities for various absorbents and zeolite N
Material Oil Absorption
Capacity
(g/100g)
Alumina 20
Bentonlte 23
Zeolite 4A • 35
Kaolin 42
Attapulgite 86
Zeolite N (Example 1} 81
Zeolite N (Example 4) 90
Zeolite N (Example 7) 103
Zeolite N (Example 8} 89
Zeolite N (Example 9) 68
Zeolite N (Example 10) 128
Zeolite N (Example 11) 140
Zeolite N (Example 13) 139
Zeolite N (Example 20) 125
■ ■ '■ 53
THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:
' 1. A process for making aluminosilicates of zeolite N structure comprising the steps of:
(i) combining a water soluble monovaient cation, a solution of hydroxyl anions
and an aluminosilicate to form a resultant mixture having a pH greater than
10 and a H2O/AI203 molar ratio in the range 30 to 220;
(ii) heating and stirring the resultant mixture to a temperature of between 50°C
and the boiling point of the mixture for a time between 1 minute and 100
hours until a crystalline product of zeolite N structure is formed as
determined by X-ray diffraction or other suitable characteristic; and
(iii) - separating the zeolite N product as a solid from the mixture.
2. A process as claimed in claim 1 wherein the water soluble monovaient cation in step
(i) is an alkali metal or an ammonium ion or mixtures of these ions.
3. A process as claimed in claim 2 wherein the alkali metal comprises a potassium ion.
4. A process as claimed in claim 2 wherein the alkali metal comprises both a potassium
and sodium ion.
5. A process as claimed in claim 2 wherein the monovaient cation comprises both
potassium and ammonium ions.
6. A process as claimed in any preceding claim wherein the resultant mixture of step (i)
also contains a halide.
7. A process as claimed in claim 6 wherein the halide is chloride.
8. A process as claimed in any preceding claim wherein the pH of the solution of
hydroxyl ions is greater than 13.
9. A process as claimed in any preceding claim wherein in step (ii) the resultant mixture
is heated to a temperature of in the range 80cC to 95°C.
10. A process as claimed in any preceding claim wherein the aluminosilicate has a Si:AI
ratio in the range 1.0 to 5.0.
11. A process as claimed in claim 10 wherein the aluminosilicate has a Si:AI ratio in the
range 1.0 to 3.0.
12. A process as claimed in claim 10 wherein the aluminosilicate is a clay.
13. A process as claimed in claim 12 wherein the clay is kaolin, meta-kaolin or
montmorillonite or mixtures thereof.
14. A process as claimed in any preceding claim wherein in step (ii) said heating is
carried out for a time in the range 2 to 24 hours.
15. A process as claimed in any preceding claim wherein the molar ratio of H2O/AI203 in
the mixture of step (i) is in the range 45 to 65.
16. A process as claimed in any preceding claim wherein in step (i) a quantity of solid
zeolite N is added to the mixture.
. 17. A process as claimed in any preceding claim wherein caustic liquor remaining in the
54 : .
mixture after step (Hi) is re-used as at least part of a solution of anions and cations in
step (i) for subsequent production of additional zeolite N product.
18. A process as claimed in claim 3 wherein the amount of potassium utilised is
governed by a molar ratio of K2O/AI203 in the range 0.3 to 15.
19. A process as claimed in claim 3 wherein the amount of potassium utilised is
governed by a molar ratio of KCI/AI203 in the range 0.0 to 15.
20. A process as claimed in claim 7 wherein the amount of chloride utilised is governed
. by a molar ratio of KCt/AI203 in the range 0.0 to 15.
21. A process as claimed in claim 2 wherein the alkali metal is sodium and the amount
of sodium utilised is governed by a molar ratio of Na2O / AI2O3 in the range 0.0 to
2.5.
22. A process as claimed in claim 2 wherein the alkali metal is sodium and the amount
of sodium utilised is governed by a molar ratio of N aCI / AI2O3 in the range 0.0 to 2.8.
23; A process as claimed in claim 7 wherein the amount of chloride utilised is governed
by a molar ratio of NaCI / AI2O3 in the range 0.0 to 2.8.
24. A process as claimed in claim 7 wherein the amou nt of chloride utilised is governed
by a molar ratio of Cl / SiO2 in the range 0.0 to 6.5.
25. A process as claimed in claim 4 wherein the amount of sodium and potassium
utilised is governed by a ratio of K/(K+Na) in the range 0.5 to 1.0.
26. A process as claimed in claim 4 wherein the amount of sodium and potassium
utilised is governed by a ratio of (K + Na - Al)/ Si in the range 2.0 to 18.0. .
27. Zeolite N produced by the process of any preceding claim or combination of
preceding claims.
28. Zeolite N produced by the process of any preceding claim having a composition
according to the formula
(M,.ai P.)i2(AlbSic)10O«(X^, Yd)2 nH2O where
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cation(s) exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
0 £ a 5 1, 1 £ c/b :£ oc, 0 s d
29. Zeolite N having a composition according to the formula
(Mi-a, PJizCAIbSic^AofXni, Yd)2 n'H2O where
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = haiide and Y is an anion and
0 c/b 5 oc, 0 5 d <. and n s>
characterised in having a BET surface area greater than 1 m2/g.
• 55
30. Zeolite N a&'daimed in claim 29 having a BET surface area between 1 m2/g and 150
mz/g. .
31. Zeolite N as claimed in claim 30 having a BET surface area between 5 m2/g and 150
m2/g. •
32. Zeolite N as claimed in any one of claims 29,30 or 31 haying a proportion of external
surface area to internal surface area of greater than 1%.
33. Zeolite N as claimed in claim 32 having a proportion of external surface area to
internal surface area of greater than 5%.
34. Zeolite N as claimed in claim 33 having a proportion of external surface area to
internal surface area of greater than 10%.
35. Zeolite N having a composition according to the formula.
• (Mi.., P.hzfAlbSytoCMXi.d, Yd)2 nH2O where
M - alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal Or
ammonium
- X = halide and Y is an anion and
0£a £1, i£c/b £oc,'0£d £1 and 1^n £10
characterised in having an X-ray diffraction pattern which has a high background
intensity of greater than 5% of a maximum peak height between the region 25°
36. Zeolite N having a.composition according to the formula
(Mi.,, Pa)i2(AlbSic)i0O«(Xi^, Yd)2 nH2O where
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
0 ^ a
when used for exchange of ammonium ions in solution.
37.. Zeolite N having a composition according to the formula
(Mi... P.)i2(AlbSi0)1004o(XiKll Yd)2 nH2O where
M - alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
0 5 a
when used for exchange of ammonium ions in the presence of alkali metal and/or.
alkaline earth metal ions in solution.
38. Zeolite N having a composition according to the formula
56
(Mi.,, Pi)i2(A!i,Sie)ioO
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
0 £ a £ 1, 1 £c/b £ cc, 0 £ d £ 1 and 1 £ n 210.
having a cation exchange capacity ranging from 100 meq per 100g to 700 meq per
100g for ammonium ions with concentrations between less than 1 mg/L to greater
than 10,000 mg/L.
39. Zeolite N as claimed in claim 38 having a cation exchange capacity greater than 200
meqpeMOOg.
40. Zeolite N having, a composition according to the formula
(ML,, P,)i2(AlbSic)ioO«(Xi.dl Yd)2 nH2O where
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
O£a-£1, i£c/b £K, 0£d £1 and i£n £10
when used for exchange of metal ions in solution.
41. Zeolite N having a composition according to the formula
(Mi* Pa)i2(AlbSie)io04o{Xw, Y«,)2 nH2O where
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
0 <. a s c x u d and n>
when used for exchange of metal ions in the presence of alkali metal or alkaline
earth metal ions in solution.
42. Zeolite N as claimed in claim 40 or 41 wherein the metal ions comprise copper, zinc,
nickel, cobalt, cadmium, silver and lead.
43. Zeolite N as claimed in claim 40,41 or42 having cation exchange capacity for metal
ions ranging from 20meq per 10Og to 400meq per 10Og!
44. Zeolite N having a composition according to the formula
(Mi* Pa)i2(AlbSic)10O«(XM, Yd)2 nH2O where
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
57
0«»a £1, 1sc/b £«;, 6sd £1 and 1*n £10
when used for adsorbing ammonia gas in the temperature range 0°C to 300°C.
45. Zeolite N having a composition according to the formula .
(ML., P.)i2(AlbSie)i(Ao(Xi.
M = alkali metal or ammonium; -
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an aniori and
0
when used for adsorbing ammonia gas in the temperature range 0°C to 300°C in the
presence of water.
46. Zeolite N having a composition according to the formula
(MM, PaJi2(AlbSic)1(Ao(XMl Yd)2 nH2O where
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
0
when used for absorbing oil.
47. Zeolite N as claimed in claim 46 when used for absorbing oil greater than 50g of oil
per 100g of Zeolite N.
48. Zeolite N having a composition according to the formula
(M1.a,Pa)12(AlbSic),oO«(X1^Yd)2 nH2O where
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
0;oc, 0
when used for removing anions from wastewater.
49. Zeolite N having a composition according to the formula
(ML,, Pa)i2(AlbSie)10O«(Xw, Yd)2 nH2O where
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
0 £ a ^ 1, 1 5 c/b £ oc, 0 £ d £ 1 and 1 5 n <.>
when used in an ammonium form to have a capacity to re-exchange alkali metal
ions from solutions containing hydroxyl ions ranging in concentration from 0.1 M to
.58 • "
2.0M. .'
50. Zeolite N as claimed in claim 49'wherein the concentration of hydroxyl ions is from
0.4 M to 1.5 M.
51. Zeolite N as claimed in claim 49 or 50 wherein the solutions containing hydroxyl ions
comprise KOH or NaOH or mixtures thereof.
52. Zeolite N having a composition according to the formula
(Mi* P«)t2(AlbSic)1o04o(Xi* Yd)2 nH2O where
. iM = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metai or
ammonium
X = halide and Y is an anion and
OS a s 1, 1 ic/b £ oc, 0 £d s 1 and 1 i n £ 10
having a removal rate of ammonium ion ranging between 50-100% from ammonium
loaded Zeolite N using a regeneration solution containing hydroxyl ions.
53. Zeolite N having a composition according to the formula
(ML,, P,)i2(AlbSie)1(>O«(Xn,, Yd)2 nH2O where
M = alkali metaf or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
Os.a ^1, 1 ic/b ioc, Osd 51 and 1 in £10
when used to re-exchange ammonium ions and/or to retain high selectivity for
ammonium ions after regeneration with a solution containing hydroxyl ions.
54. Zeolite N having a composition according to the formula
(Mt-a. PaMAIbSUtoO^X^, Yd)2 nH2O where
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
0 £ a
when used to kill gram positive or gram negative bacteria.
. 55. Zeolite N having a composition according to the .formula
(M,*. P.)i2(AlbSic)10O«(XMl Yd)2 nH2O where
M = potassium or sodium or ammonium;
P = silver or zinc
X = halide and Y is an anion and
Osa s1, 1
when used to kill gram positive or gram negative bacteria.
59
56. Zeolite N having a composition according to the formula
(Mn, pB)i2(AlbSie)1004o(XM, Yd)2 nH2O where
M = potassium and ammonium;
P = silver and zinc
X = halide and Y is an anion and
0£a £1, i£c/b £«, 0£d £1 and 1'£n £10
when used to kill gram positive or gram negative bacteria.
57. Zeolite N having a composition according to the formula
(M,.., PO^AIbSi^oO^X,.* Y
M = alkali metal or ammonium;
P = alkali metal, ammonium or metal cations exchanged in lieu of alkali metal or
ammonium
X = halide and Y is an anion and
0£a £i, i£c/b £«, 0£d £1 and i£rr £10.
where c/b is greater than 1.
58. Zeolite N as claimed in claim 57 wherein c/b has an upper value of 5.
59. Zeolite N as claimed in claim 57 wherein c/b has an upper value of 3.
60. Zeolite N as claimed in any one of claims 28-59 wherein Y is hydroxy! or halide.
61. Zeolite N as claimed in claim 60 wherein Y is chloride.
60
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A process for making aluminosilicates of zeolite N structure comprising the steps of: (i) combining a water soluble
monovalent cation, a solution of hydroxyl anions and an aluminosilicate to form a resulant mixture having a pH greater than 10 and
a H2O/Al2O3 ratio in the range 30 to 220; (ii) heating the resultant mixture to a temperature of between 50oC and the boiling point of
the mixture for a time between 1 minute and 100 hours until a crystalline product of zeolite N structure is formed as determined by
X-ray diffraction or other suitable characteristic; and (iii) separating the zeolite N product as a solid from the mixture.
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