Title of Invention	A PROCESS FOR THE PREPARATION OF ULTRAFILTRATION MEMBRANES BASED ON POLYACRYLONITRILE AND ITS COPOLYMERS.
Abstract	A process for the preparation of ultrafiltration membranes based on polyacrylonitrile and its copolymers by preparing a saturated solution of a di- or trivalent metal salt in an organic solvent, filtering the resulting solution to remove undissolved particles, adding the poly(acrylonitrile) polymer or its copolymer in an amount in the range of 10 to 20% by weight to the above solution, mixing thoroughly to obtain a homogeneous solution, casting this solution by conventional technique, and gelling the cast film in a bath containing water to obtain the polymeric membrane.

Title of Invention

A PROCESS FOR THE PREPARATION OF ULTRAFILTRATION MEMBRANES BASED ON POLYACRYLONITRILE AND ITS COPOLYMERS.

Abstract

A process for the preparation of ultrafiltration membranes based on polyacrylonitrile and its copolymers by preparing a saturated solution of a di- or trivalent metal salt in an organic solvent, filtering the resulting solution to remove undissolved particles, adding the poly(acrylonitrile) polymer or its copolymer in an amount in the range of 10 to 20% by weight to the above solution, mixing thoroughly to obtain a homogeneous solution, casting this solution by conventional technique, and gelling the cast film in a bath containing water to obtain the polymeric membrane.

Full Text	The present invention relates to a process for the preparation of ultrafiltration membranes based on polyacrylonitrile or copolymers based on acrylonitrile and other monomers. The membranes made by the process of this invention have improved separation properties giving a substantial increase in purity of fluids permeating through the membrane. Such membranes are highly useful for microbiological purification of water during which virus, bacteria and cysts are to be removed with certifiable high log reductions in particle counts. Polymeric ultrafiltration membranes are commonly prepared by the "phase inversion" method (R.E. Resting, 1971, Synthetic Polymeric Membranes, McGraw-Hill) in which a thin film of a polymer solution is solidified by immersion in a bath containing a non-solvent. Poly(acrylonitrile) and its copolymers can be dissolved in polar organic solvents such as dimethyl formamide (DMF), dimethyl acetamide, or dimethyl sulfoxide for purposes of membrane preparation (U.S. patent 4,025,439) . By virtue of relatively low cost, solvent power and safety in handling, dimethyl formamide is a preferred solvent for preparing the polyacrylonitrile containing solution. For similar reasons, water is a preferred non-solvent. The use of copolymers based on acrylonitrile with other monomers have been suggested as materials for ultrafiltration membranes eg. U.S. patent nos. 4,181,694 (isobutene, vinyledene chloride, butadiene, methacrylonitrile, ethylene vinyl ether as comonomers), U.S. patent 3,950,257 (vinyl pyrrolidone as comonomer) and U.K patent application GB 2,096,941A (methyl methacrylate and sodium salt of vinylsulfonic acid as comonomers). The prior art mentioned above do not describe the preparation of PAN ( Polyacrylonitrile)membranes using salts. The membranes prepared by the prior art are not useful in the separation of microbes, viruses in the process of purification of water. It is therefore an object of the present invention to provide a process for the preparation of the ultra-filtration membranes based on poly(acrylonitrile) and its copolymers useful for purification of water free of microbial contaminants. Accordingly the present invention provides a process for the preparation of ultrafiltration membranes based on polyacrylonitrile and its copolymers which comprises preparing a saturated solution of a di- or trivalent metal salt such as herein described in an organic solvent as herein described, filtering the resulting solution to remove undissolved particles, adding the poly(acrylonitrile) polymer or its copolymer in an amount in the range of 10 to 20% by weight to the above solution, mixing thoroughly to obtain a homogeneous solution, casting this solution by conventional technique, and gelling the cast film in a bath containing water to obtain the polymeric membrane. In an embodiment of the present invention, the solution used for the membrane contains between 0.5 to 4% of a di- or triva-lent metal salt which is soluble both in the solvent used to dissolve the polymer as well as in the non-solvent in which the polymer solution is immersed. The polymers used include polyacrylonitrile or copolymers of acrylonitrile and acrylamide, prepared by any conventional method. The amount of acrylamide in the copolymer used may be preferably 10-20% . The acrylamide containing polymer will yield membranes with better fouling resistance in the same applications . The solvents used for preparing the solution of the polymers may be selected from well known solvents for polyacrylonitrile such as dimethyl formamide (DMF), dimethyl sulfoxide or dimethyl acetamide. The non-solvent used to coagulate the polymer may be or lower alcohols such as methanol, ethanol etc. The di- or trivalent salt which is incorporated to the polymer solution must be soluble in both the solvent (e.g. dimethyl formamide) as well as nonsolvent (e.g. water). Suitable examples of such salts are chlorides and nitrates of Zn, Fe and Al. The purification ability of the membrane can be expressed in the following related manners: R ( Rejection) = 1- ( concentration of species A in the permeate / concentration of species A in the feed) or, LR (log reduction) = log 10 (concentration of species A in the feed / concentration of species in the permeate) LR can also be expressed as log 10 [1/(1 - R) ] . Ultrafiltration membranes are described by their nominal molecular weight cut off (MWCO) defined arbitrarily as the molecular wt of the species for which R is approximately 0.9 (Cheryan M., Ultrafiltration Handbook, 1986, Technomic Publishing Co.). The membranes prepared as per the process of the present invention have unexpectedly high values of LR for bacteria, virus and cyst removal in comparison with other membranes with similar MWCO values made by a conventional method. These membranes appear to have a narrower pore size distribution, so defects and large pores which allow passage of virus, bacteria, cysts are greatly eliminated. The presence of such large pores/defects can be readily detected by the bubble point technique. Correlations of LR for bacteria with bubble points are well established for microfiltration membranes (Goel et al , in Membrane Handbook, 1992, Van Nostrand Reinhold). The membranes of this invention have higher bubble points than the conventionally made membranes. While the membranes of this invention have higher values of LR compared to conventional membranes with similar MWCO values, the membrane permeability for water is not greatly reduced. The process of the present invention is described herein with the help of examples which are illustrative only and should not be construed to limit the scope of the present invention in any manner. Example 1 : A solution was prepared by adding polyacrylonitrile in dimethyl formamide (DMF) in order to make a 13% polymer solution. The mixture was stirred until dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of 3-5 samples cut from each membrane is summarized in Table 1. Example 2 : A solution was prepared by first dissolving 4 % of urea in DMF, filtering the solution and then 13% polyacrylonitrile was added and stirred till complete dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of these membranes is also summarized in Table 1. It can be seen that urea as an additive does not improve the membrane performance . Example 3 : A solution was prepared by first dissolving 4 % of LiCl in DMF, filtering the solution and then 13% polyacrylonitrile was added and stirred till complete dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of these membranes is also summarized in Table 1. Addition of a monovalent metal based salt such as LiCl gave membranes with less defects; however, this was with substantial flux penalty. Example 4 : A solution was prepared by first dissolving 4 % of ZnCl2 in DMF, filtering the solution and then 13% polyacrylonitrile was added and stirred till complete dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of these membranes is also summarized in Table 1. Membranes cast from solutions containing ZnCl2 have similar ultrafiltration performance (water flux, rejections of BSA or PEG) as the membrane cast from solution without additives. However, the incidence of defects is less as shown by the higher value of the average bubble points and less scatter in the bubble point measurements . Example 5 : A solution was prepared by first dissolving 4 % of AlCl^ in DMF, filtering the solution and then 13% polyacrylonitrile was added and stirred till complete dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of these membranes is also summarized in Table 1. Membranes cast from solutions containing AlCl3 have improved properties similar to those cast with ZnCl2 Example 6 : A solution was prepared by first dissolving 4 % of Fed-, in DMF, filtering the solution and then 13% polyacrylonitrile was added and stirred till complete dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes was washed in water overnight. The membrane was characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of the membrane is also summarized in Table 1. Membranes cast from solutions containing FeCl3 has improved properties similar to those cast with ZnCl2 Table 1. Performance characteristics of polyacrylonitrile membranes cast from solutions with DMF and various additives. (Table Removed) * at 2.0 kg/cm2 + Rejection of bovine serum albumin measured in stirred cell (Amicon) with 0.1 % BSA buffered solution at pH 7.5 and 1.0 bars. # Rejection of polyethylene glycol measured in stirred cell (Amicon) with 0.5 % solution at 1.0 bars. @ Only one sample tested. Example 7 The membrane cast as per the procedure of Example 2 using ZnCl2 as an additive was compared to the membrane prepared without this additive when both membranes were wound in the form of spiral modules. E coli containing broth was circulated through the modules at 0.7 bars at 1 1pm. The permeate was collected and assayed for bacterial content along with feed side samples. The feed contained 108 E.coli counts /ml. The results are shown in Table 2. Table 2: E.Coli reduction in spiral modules made from polyacrylo-nitrile membranes cast from solutions containing no additive and with ZnCl2 as an additive. (Table Removed) * measured at 0.7 kg/cnr" Example 8 A copolymer of poly (acrylonitrile-acrylamide) was prepared by solution polymerization of the two monomers acrylonitrile and acrylamide using acidic catalyst (HN03) as per the procedure of Bhadani and Kundu (Macromol. Chem., Rapid Commun. 1, 1980, p281). The copolymer containing 15 mole% of acrylamide and 85 mole% acrylonitrile had intrinsic viscosity between 0.8 to 1.0 dl/gm. Two solutions were made each containing 18% copolymer in DMF, one containing ZnC12 the other one without. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The bubble point profiles of both membranes are shown in Table 3. This shows that the ZnCl2 additive greatly depresses the incidence of large pores, in the case of acrylamide-acrylonitrile copolymer as well. The ultrafiltration membranes cast from the solution containing a di- or trivalent metal salt have a reduced number of macrovoids, defects etc; thus giving better separation without significant loss in flux. These membranes are suitable for microbiological purification of water and other aqueous media. Membranes made by a similar process but omitting the salt additive to the casting solution have a large number of defects making them unsuitable for microbiological purification. Table 3 :Air flow rate through poly(acrylonitrile-acrylamide) copolymer membrane (Table Removed) Example 9 A solution was prepared by first dissolving 4 % of ZnCl2 in DMF, filtering the solution and then 19% polyacrylonitrile was added and stirred till complete dissolution. The resulting solution was extruded under 50 psi nitrogen pressure through a hollow fiber spinneret. The resulting membrane was obtained as a hollow fiber with internal diameter of 0.7 mm and outer diameter of 1.3 mm. We Claim : 1. A process for the preparation of ultrafiltration membranes based on polyacrylonitrile and its copolymers which comprises preparing a saturated solution of a di- or trivalent metal salt such as herein described in an organic solvent as herein described, filtering the resulting solution to remove undissolved particles, adding the poly(acrylonitrile) polymer or its copolymer in an amount in the range of 10 to 20% by weight to the above solution, mixing thoroughly to obtain a homogeneous solution, casting this solution by conven tional technique, and gelling the cast film in a bath containing water to obtain the polymeric membrane. 2. A process as claimed in claim 1 wherein the salt used is selected from chlorides or nitrates of Zn, Al, or Fe . 3. A process as claimed in claims 1 to 2, wherein the solvent used for dissolving the polymer is selected from dimethyl formamide, dimethyl acetamide or dimethyl sulfoxide. 4. A process for the preparation of ultrafiltration membranes based on poly(acrylonitrile) and its copoly mer substantially herein described with reference to examples.

Full Text

The present invention relates to a process for the preparation of ultrafiltration membranes based on polyacrylonitrile or copolymers based on acrylonitrile and other monomers. The membranes made by the process of this invention have improved separation properties giving a substantial increase in purity of fluids permeating through the membrane. Such membranes are highly useful for microbiological purification of water during which virus, bacteria and cysts are to be removed with certifiable high log reductions in particle counts.
Polymeric ultrafiltration membranes are commonly prepared by the "phase inversion" method (R.E. Resting, 1971, Synthetic Polymeric Membranes, McGraw-Hill) in which a thin film of a polymer solution is solidified by immersion in a bath containing a non-solvent. Poly(acrylonitrile) and its copolymers can be dissolved in polar organic solvents such as dimethyl formamide (DMF), dimethyl acetamide, or dimethyl sulfoxide for purposes of membrane preparation (U.S. patent 4,025,439) . By virtue of relatively low cost, solvent power and safety in handling, dimethyl formamide is a preferred solvent for preparing the polyacrylonitrile containing solution. For similar reasons, water is a preferred non-solvent.
The use of copolymers based on acrylonitrile with other monomers have been suggested as materials for ultrafiltration membranes eg. U.S. patent nos. 4,181,694 (isobutene, vinyledene chloride, butadiene, methacrylonitrile, ethylene vinyl ether as

comonomers), U.S. patent 3,950,257 (vinyl pyrrolidone as comonomer) and U.K patent application GB 2,096,941A (methyl methacrylate and sodium salt of vinylsulfonic acid as comonomers).
The prior art mentioned above do not describe the preparation of PAN ( Polyacrylonitrile)membranes using salts. The membranes prepared by the prior art are not useful in the separation of microbes, viruses in the process of purification of water.
It is therefore an object of the present invention to provide a process for the preparation of the ultra-filtration membranes based on poly(acrylonitrile) and its copolymers useful for purification of water free of microbial contaminants.
Accordingly the present invention provides a process for the preparation of ultrafiltration membranes based on polyacrylonitrile and its copolymers which comprises preparing a saturated solution of a di- or trivalent metal salt such as herein described in an organic solvent as herein described, filtering the resulting solution to remove undissolved particles, adding the poly(acrylonitrile) polymer or its copolymer in an amount in the range of 10 to 20% by weight to the above solution, mixing thoroughly to obtain a homogeneous solution, casting this solution by conventional technique, and gelling the cast film in a bath containing water to obtain the polymeric membrane.

In an embodiment of the present invention, the solution used for the membrane contains between 0.5 to 4% of a di- or triva-lent metal salt which is soluble both in the solvent used to dissolve the polymer as well as in the non-solvent in which the polymer solution is immersed.
The polymers used include polyacrylonitrile or copolymers of acrylonitrile and acrylamide, prepared by any conventional method. The amount of acrylamide in the copolymer used may be preferably 10-20% . The acrylamide containing polymer will yield membranes with better fouling resistance in the same applications .
The solvents used for preparing the solution of the polymers may be selected from well known solvents for polyacrylonitrile such as dimethyl formamide (DMF), dimethyl sulfoxide or dimethyl acetamide.
The non-solvent used to coagulate the polymer may be or lower alcohols such as methanol, ethanol etc.
The di- or trivalent salt which is incorporated to the polymer solution must be soluble in both the solvent (e.g. dimethyl formamide) as well as nonsolvent (e.g. water). Suitable examples of such salts are chlorides and nitrates of Zn, Fe and Al.
The purification ability of the membrane can be expressed in

the following related manners:
R ( Rejection) = 1- ( concentration of species A in the permeate
/ concentration of species A in the feed)
or,
LR (log reduction) = log 10 (concentration of species A in the feed / concentration of species in the permeate) LR can also be expressed as log 10 [1/(1 - R) ] .
Ultrafiltration membranes are described by their nominal molecular weight cut off (MWCO) defined arbitrarily as the molecular wt of the species for which R is approximately 0.9 (Cheryan M., Ultrafiltration Handbook, 1986, Technomic Publishing Co.).
The membranes prepared as per the process of the present invention have unexpectedly high values of LR for bacteria, virus and cyst removal in comparison with other membranes with similar MWCO values made by a conventional method. These membranes appear to have a narrower pore size distribution, so defects and large pores which allow passage of virus, bacteria, cysts are greatly eliminated. The presence of such large pores/defects can be readily detected by the bubble point technique. Correlations of LR for bacteria with bubble points are well established for microfiltration membranes (Goel et al , in Membrane Handbook, 1992, Van Nostrand Reinhold). The membranes of this invention have higher bubble points than the conventionally made membranes.

While the membranes of this invention have higher values of LR compared to conventional membranes with similar MWCO values, the membrane permeability for water is not greatly reduced.
The process of the present invention is described herein with the help of examples which are illustrative only and should not be construed to limit the scope of the present invention in any manner.
Example 1 :
A solution was prepared by adding polyacrylonitrile in dimethyl formamide (DMF) in order to make a 13% polymer solution. The mixture was stirred until dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of 3-5 samples cut from each membrane is summarized in Table 1.
Example 2 :
A solution was prepared by first dissolving 4 % of urea in DMF, filtering the solution and then 13% polyacrylonitrile was added and stirred till complete dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The

membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of these membranes is also summarized in Table 1. It can be seen that urea as an additive does not improve the membrane performance .
Example 3 :
A solution was prepared by first dissolving 4 % of LiCl in DMF, filtering the solution and then 13% polyacrylonitrile was added and stirred till complete dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of these membranes is also summarized in Table 1. Addition of a monovalent metal based salt such as LiCl gave membranes with less defects; however, this was with substantial flux penalty.
Example 4 :
A solution was prepared by first dissolving 4 % of ZnCl2 in DMF, filtering the solution and then 13% polyacrylonitrile was added and stirred till complete dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of

these membranes is also summarized in Table 1. Membranes cast from solutions containing ZnCl2 have similar ultrafiltration performance (water flux, rejections of BSA or PEG) as the membrane cast from solution without additives. However, the incidence of defects is less as shown by the higher value of the average bubble points and less scatter in the bubble point measurements .
Example 5 :
A solution was prepared by first dissolving 4 % of AlCl^ in DMF, filtering the solution and then 13% polyacrylonitrile was added and stirred till complete dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The performance of these membranes is also summarized in Table 1. Membranes cast from solutions containing AlCl3 have improved properties similar to those cast with ZnCl2

Example 6 :
A solution was prepared by first dissolving 4 % of Fed-, in DMF, filtering the solution and then 13% polyacrylonitrile was added and stirred till complete dissolution. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes was washed in water overnight. The membrane was characterized for their pure water flux, rejection

of PEG and BSA and their water bubble points. The performance of the membrane is also summarized in Table 1. Membranes cast from solutions containing FeCl3 has improved properties similar to those cast with ZnCl2
Table 1. Performance characteristics of polyacrylonitrile membranes cast from solutions with DMF and various additives.
(Table Removed)

* at 2.0 kg/cm2
+ Rejection of bovine serum albumin measured in stirred cell (Amicon) with 0.1 % BSA buffered solution at pH 7.5 and 1.0 bars.
# Rejection of polyethylene glycol measured in stirred cell
(Amicon) with 0.5 % solution at 1.0 bars.
@ Only one sample tested.

Example 7
The membrane cast as per the procedure of Example 2 using ZnCl2 as an additive was compared to the membrane prepared without this additive when both membranes were wound in the form of spiral modules. E coli containing broth was circulated through the modules at 0.7 bars at 1 1pm. The permeate was collected and assayed for bacterial content along with feed side samples. The feed contained 108 E.coli counts /ml. The results are shown in Table 2.
Table 2: E.Coli reduction in spiral modules made from polyacrylo-nitrile membranes cast from solutions containing no additive and with ZnCl2 as an additive.
(Table Removed)
* measured at 0.7 kg/cnr"

Example 8
A copolymer of poly (acrylonitrile-acrylamide) was prepared by solution polymerization of the two monomers acrylonitrile and acrylamide using acidic catalyst (HN03) as per the procedure of Bhadani and Kundu (Macromol. Chem., Rapid Commun. 1, 1980, p281). The copolymer containing 15 mole% of acrylamide and 85 mole% acrylonitrile had intrinsic viscosity between 0.8 to 1.0 dl/gm. Two solutions were made each containing 18% copolymer in DMF, one containing ZnC12 the other one without. It was then cast by knife coating on a moving porous support and gelled in 20°C water. The cast membranes were washed in water overnight. The membranes were characterized for their pure water flux, rejection of PEG and BSA and their water bubble points. The bubble point profiles of both membranes are shown in Table 3. This shows that the ZnCl2 additive greatly depresses the incidence of large pores, in the case of acrylamide-acrylonitrile copolymer as well.
The ultrafiltration membranes cast from the solution containing a di- or trivalent metal salt have a reduced number of macrovoids, defects etc; thus giving better separation without significant loss in flux. These membranes are suitable for microbiological purification of water and other aqueous media. Membranes made by a similar process but omitting the salt additive to the casting solution have a large number of defects making them unsuitable for microbiological purification.

Table 3 :Air flow rate through poly(acrylonitrile-acrylamide) copolymer membrane
(Table Removed)

Example 9
A solution was prepared by first dissolving 4 % of ZnCl2 in DMF, filtering the solution and then 19% polyacrylonitrile was added and stirred till complete dissolution. The resulting solution was extruded under 50 psi nitrogen pressure through a hollow fiber spinneret. The resulting membrane was obtained as a hollow fiber with internal diameter of 0.7 mm and outer diameter of 1.3 mm.

We Claim :
1. A process for the preparation of ultrafiltration
membranes based on polyacrylonitrile and its copolymers
which comprises preparing a saturated solution of a
di- or trivalent metal salt such as herein described in
an organic solvent as herein described, filtering the
resulting solution to remove undissolved particles,
adding the poly(acrylonitrile) polymer or its copolymer
in an amount in the range of 10 to 20% by weight to
the above solution, mixing thoroughly to obtain a
homogeneous solution, casting this solution by conven
tional technique, and gelling the cast film in a bath
containing water to obtain the polymeric membrane.
2. A process as claimed in claim 1 wherein the salt
used is selected from chlorides or nitrates of Zn, Al,
or Fe .
3. A process as claimed in claims 1 to 2, wherein the
solvent used for dissolving the polymer is selected
from dimethyl formamide, dimethyl acetamide or dimethyl
sulfoxide.
4. A process for the preparation of ultrafiltration
membranes based on poly(acrylonitrile) and its copoly
mer substantially herein described with reference to
examples.

Documents:

1811-del-1996-abstract.pdf

1811-del-1996-claims.pdf

1811-del-1996-complete specification (granded).pdf

1811-DEL-1996-Correspondence-Others.pdf

1811-del-1996-correspondence-po.pdf

1811-del-1996-description (complete).pdf

1811-del-1996-form-1.pdf

1811-del-1996-form-2.pdf

1811-del-1996-form-3.pdf

1811-del-1996-form-4.pdf

1811-del-1996-petition-138.pdf

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Patent Number

218226

Indian Patent Application Number

1811/DEL/1996

PG Journal Number

40/2008

Publication Date

03-Oct-2008

Grant Date

31-Mar-2008

Date of Filing

14-Aug-1996

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	SUDHIR SHARADCHANDRA KULKARNI	NATIONAL CHEMICAL LABORATORY, PUNE, MAHARASHTRA, INDIA.
2	MADHURI HIMMATRAO SHINDE	NATIONAL CHEMICAL LABORATORY, PUNE, MAHARASHTRA, INDIA.
3	DEEPAK ANANDRAO MUSALE	NATIONAL CHEMICAL LABORATORY, PUNE, MAHARASHTRA, INDIA.

PCT International Classification Number

B01D 13/04

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA