Indian Patents. 279435:A METHOD FOR THE REMOVAL OF ARSENITE FROM ARSENIC CONTAMINATED WATER

Title of Invention	A METHOD FOR THE REMOVAL OF ARSENITE FROM ARSENIC CONTAMINATED WATER
Abstract	A method for the removal of arsenite (As3+) from arsenic contaminated water comprising: adding integrated steel industry cold rolled mill fines to the contaminated water; subjecting said water containing CRM fines to the step of stirring for 1 to 3 hours and subsequently allow to settle the CRM fines for 1 to 3 hours; filtering the water to produce decontaminated water.

Full Text	FIELD OF THE INVENTION: This invention relates to a method for the removal of arsenite from arsenic contaminated water. The present invention also relates to the absorption of arsenite (As3+) by using integrated steel industry Cold Rolled Mill (CRM) fines, which is the waste product of this particular industry. BACKGROUND OF THE INVENTION: Arsenic (As)-contaminated drinking water is a major problem around the world. The arsenic contamination is caused by the physical geography chemistry change and human activities such as mining, waste water release from industries, chemistry process etc. Millions of human being from the various countries such as Bangladesh, India, Vietnam, Hungary, Romania, Mexico, Argentina, Chile and the United States face significant challenges in meeting the newly lowered standards (WHO standard, 10 part per billion (ppb) for As in drinking water (Zhao, 2002). Arsenic levels in these areas can be as high as few thousands of ppb. Arsenic is well known as a useful compound in industrial applications such as smelting agriculture pesticides and insecticides. However, arsenic has also been considered as a strong poisonous chemical due to its odorless and testless nature (Buchanam, 1962; Ferguson and Gavis, 1972). It is a carcinogen which causes many cancers including skin, colon, kidney, lung and bladder as well as cardiovascular disease. According to the recent report of United States National Academy of Science and United States National Council, even the small amount (3ppb) of arsenic, the risk of bladder and lung cancer is between four to seven deaths per 10, 000 people and at l0ppb (WHO standard) this risk increases 12 to 23 deaths per 10,000 people (NRC, 2001). Commonly arsenic exists in the environment as arsenate (As5+) arsenite (As3+), monmethylarsenic acid (MMA) and dimethylarsinic acid (DMA) (Gu et al, 2005). Arsenic mainly presents in inorganic forms, where it may be easily dissolved in water which is very dangerous. In order to get the potable water by removing the arsenic components from it, several techniques have been developed such as precipitation, adsorption, biological sequestration and foam flotation [L.G.Twidwell et al, 1999]. However, these technologies are either not well suited in actual field or economically not affordable by common man [Hossain et al., 2005]. Moreover, all these technologies are good only for the removal of As(V) but very little data are available for As(III). As(III) is more toxic than As(V) and may cause skin cancer and neurological damage. There is an urgent need to develop a low-cost method for the purpose of reducing AS (III) for supplying potable water. OBJECTS OF THIS INVENTION: An object of this invention is to propose a method for the removal of arsenite from arsenic contaminated water; Another object of this invention is to propose a simple method for the removal of arsenic using integrated steel industry Cold Roller Mill (CRM) fines; Still another object of this invention is to provide medium, which can remove As3+ which does not need pre-treatment of oxidation; Further object of this invention is to propose an effective, efficient and commercially feasible solution for the problem of removal of arsenic from water. SUMMARY OF THE INVENTION: According to this invention there is provided a method for the removal of arsenite (As3+) from arsenic contaminated water comprising: adding integrated steel industry cold rolled mill fines to the contaminated water; subjecting said water containing CRM fines to the step of stirring for 1 to 3 hours and subsequently allow to settle the CRM fines for 1 to 3 hours; filtering the water to produce decontaminated water. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS: Figure 1 is the X-ray diffraction (XRD) pattern of integrated steel plant Cold Rolled Mill (CRM) fines, where the main chemical component (~100%) is Fe2O3. Figure 2 is the FEG-SEM analysis of CRM fines, which reveals the particle size of these fines, are in the range of 100-300nm. Figure 3 is the arsenic removal test experiment, which showed the removal of arsenic (As3+) in water from ~ 200ppb to ~ 70 ppb by using CRM fines. Figure 4 is the arsenic removal test experiment, which showed the removal of arsenic (As3+) in water from ~ 70ppb to ~ 0 ppb by using CRM fines. DETAILED DESCRIPTION OF THE INVENTION: The present invention relates to the technique for complete removal of arsenic (As3+) from arsenic contaminated water. It is directed to the absorption of arsenic (As3+) in water by using the steel industry waste product. There are number of iron oxide fines sources in integrated steel plant. The chemical and size analysis of these fines reveals that the integrated steel plant Cold Rolled Mill (CRM) fines are very suitable candidate for low cost arsenic removal system. The chemical analysis of CRM fines shows the presence of 99.57% of Fe2O3. The rietveld analysis of X-ray diffraction pattern (FIG. 1) of these fines shows the peaks of only ferrous oxide (Fe2O3). This intern reveals that almost of 100% Fe2O3 is present in the fines. The present invention further directed to an efficient arsenic removal system by using CRM fines with particle size are in the range of 100 to 300nm, where this fines of size 100 to 300nm are the waste product of CRM and know as CRM fines. The size analyses of these fines are observed by using Field Emission Gun-Scanning Electron Microscopy (FEG-SEM) (Fig.2). In order to make the arsenic contaminated water for the purpose of experimentation, the appropriate amount of sodium arsenate (NaAsO2) salt dissolved in the water. Initially the 500ppb (0.5mg of As in one litre of water) solution made by adding 0.865 mg of sodium arsenate into one litre of water. Subsequently this solution stirred for 1-2 minutes to assure the complete and homogenous assimilation of sodium arsenate into water. The 200ppb and 70ppb of arsenic solution are made by adding the 1.5 litres and 6.1 litres of water respectively, in the initially a made of arsenic solution (in 1 litre of water). The concentration of arsenic in water has confirmed by using Merck chemical (Merckoquant 117927) arsenic test kit. The initial experiment for arsenic removal test is carried out by taking one litre of 200ppb arsenic (As3+) contaminated water solution. Subsequently 100-200 mg of CRM fines are added in the 200ppb arsenic contaminated water. The CRM fines arsenic contaminated water is stirred for 1-3 hours. The stirring exercise leads to the absorption of arsenic by CRM fines. The elements other then ferrous oxide present in CRM fines may be acting as a catalyst for oxidation of arsenite (As3+) and thus assisting ferrous oxide for the absorption of arsenic. The stirred CRM fines mixed arsenic contaminated water kept for 1-3 hours, which assure the settling of CRM fines. This water is filtered in 20-40 minutes by using a normal water filter candle which is mainly made of plaster of paris, sand and binder, to assure that the iron free water comes out from the filter. The arsenic concentration in filtered water has observed by using Merck chemical (Merckoquant 117927) arsenic test kit, which reveals the final concentration of arsenic in water is ~70ppb (Fig.3). 100-1000 mg of Cold Rolled Mill fines was added to reduce As3+ concentration from ~70ppb to ~0ppb arsenic contaminated water of one litre. The final experiment for arsenic removal test is carried out by taking one litre of 70ppb arsenic (As3+) contaminated water solution. Subsequently preferably 100-200 mg of CRM fines are added in the 70ppb arsenic contaminated water. The CRM fines arsenic contaminated water is stirred for 1-3 hours. The stirring exercise leads to the absorption of arsenic by CRM fines. The elements other then ferrous oxide present in CRM fines may be acting as a catalyst for oxidation of arsenite (As3+) and thus assisting ferrous oxide for the absorption of arsenic. The stirred CRM fines mixed arsenic contaminated water kept for 1-3 hours, which assure the settling of CRM fines. This water is filtered in 20-40 minutes by using a normal water filter candle which is mainly made of plaster of paris, sand and binder, to assure that the iron free water comes out from the filter. The arsenic concentration in filtered water has observed by using Merck chemical (Merckoquant 117927) arsenic test kit, which reveals the final concentration of arsenic in water is ~0 ppb (Fig.4). WE CLAIM: 1. A method for the removal of arsenite (As3+) from arsenic contaminated water comprising: adding integrated steel industry Cold Rolled Mill fines to the contaminated water; subjecting said water containing CRM fines to the step of stirring for 1 to 3 hours and subsequently allow to settle the CRM fines for 1 to 3 hours; filtering the water to produce decontaminated water. 2. The method as claimed in claim 1, wherein the 100-200 mg of Cold Rolled Mill fines was added to reduce As3+ concentration from ~200ppb to ~70ppb arsenic contaminated water of one litre. 3. The method as claimed in claim 1, wherein the 100-1000 mg (preferable in the range of 100-200 mg) of Cold Rolled Mill fines was added to reduce As3+ concentration from ~70ppb to ~0ppb arsenic contaminated water of one litre. 4. The method as claimed in claim 1, wherein the water was filtered for 20-40 minutes by using a normal water filter candle made of plaster of paris, sand and binder to ensure that iron free water comes out from the filter. 5. The method as claimed in claim 1, wherein the particle size of the fines are in the range of 100-300nm. 6. The method as claimed in claim 1, wherein the said cold rolled mill (CRM) fines contain (~100%) Fe2O3. A method for the removal of arsenite (As3+) from arsenic contaminated water comprising: adding integrated steel industry cold rolled mill fines to the contaminated water; subjecting said water containing CRM fines to the step of stirring for 1 to 3 hours and subsequently allow to settle the CRM fines for 1 to 3 hours; filtering the water to produce decontaminated water.

Full Text

FIELD OF THE INVENTION:
This invention relates to a method for the removal of arsenite from arsenic contaminated water.
The present invention also relates to the absorption of arsenite (As3+) by using integrated steel industry Cold Rolled Mill (CRM) fines, which is the waste product of this particular industry.
BACKGROUND OF THE INVENTION:
Arsenic (As)-contaminated drinking water is a major problem around the world. The arsenic contamination is caused by the physical geography chemistry change and human activities such as mining, waste water release from industries, chemistry process etc. Millions of human being from the various countries such as Bangladesh, India, Vietnam, Hungary, Romania, Mexico, Argentina, Chile and the United States face significant challenges in meeting the newly lowered standards (WHO standard, 10 part per billion (ppb) for As in drinking water (Zhao, 2002). Arsenic levels in these areas can be as high as few thousands of ppb. Arsenic is well known as a useful compound in industrial applications such as smelting agriculture pesticides and insecticides. However, arsenic has also been considered as a strong poisonous chemical due to its odorless and testless nature (Buchanam, 1962; Ferguson and Gavis, 1972). It is a carcinogen which causes many cancers including skin, colon, kidney, lung and bladder as well as cardiovascular disease. According to the recent report of United States National Academy of Science and United States National Council, even the small amount (3ppb) of arsenic, the risk of bladder and lung cancer is between four to

seven deaths per 10, 000 people and at l0ppb (WHO standard) this risk increases 12 to 23 deaths per 10,000 people (NRC, 2001). Commonly arsenic exists in the environment as arsenate (As5+) arsenite (As3+), monmethylarsenic acid (MMA) and dimethylarsinic acid (DMA) (Gu et al, 2005). Arsenic mainly presents in inorganic forms, where it may be easily dissolved in water which is very dangerous. In order to get the potable water by removing the arsenic components from it, several techniques have been developed such as precipitation, adsorption, biological sequestration and foam flotation [L.G.Twidwell et al, 1999]. However, these technologies are either not well suited in actual field or economically not affordable by common man [Hossain et al., 2005]. Moreover, all these technologies are good only for the removal of As(V) but very little data are available for As(III). As(III) is more toxic than As(V) and may cause skin cancer and neurological damage. There is an urgent need to develop a low-cost method for the purpose of reducing AS (III) for supplying potable water.
OBJECTS OF THIS INVENTION:
An object of this invention is to propose a method for the removal of arsenite from arsenic contaminated water;
Another object of this invention is to propose a simple method for the removal of arsenic using integrated steel industry Cold Roller Mill (CRM) fines;
Still another object of this invention is to provide medium, which can remove As3+ which does not need pre-treatment of oxidation;

Further object of this invention is to propose an effective, efficient and commercially feasible solution for the problem of removal of arsenic from water.
SUMMARY OF THE INVENTION:
According to this invention there is provided a method for the removal of
arsenite (As3+) from arsenic contaminated water comprising:
adding integrated steel industry cold rolled mill fines to the contaminated
water;
subjecting said water containing CRM fines to the step of stirring for 1 to
3 hours and subsequently allow to settle the CRM fines for 1 to 3 hours;
filtering the water to produce decontaminated water.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 is the X-ray diffraction (XRD) pattern of integrated steel plant
Cold Rolled Mill (CRM) fines, where the main chemical component
(~100%) is Fe2O3.
Figure 2 is the FEG-SEM analysis of CRM fines, which reveals the
particle size of these fines, are in the range of 100-300nm.
Figure 3 is the arsenic removal test experiment, which showed the
removal of arsenic (As3+) in water from ~ 200ppb to ~ 70 ppb by using
CRM fines.
Figure 4 is the arsenic removal test experiment, which showed the
removal of arsenic (As3+) in water from ~ 70ppb to ~ 0 ppb by using CRM
fines.

DETAILED DESCRIPTION OF THE INVENTION:
The present invention relates to the technique for complete removal of arsenic (As3+) from arsenic contaminated water. It is directed to the absorption of arsenic (As3+) in water by using the steel industry waste product. There are number of iron oxide fines sources in integrated steel plant. The chemical and size analysis of these fines reveals that the integrated steel plant Cold Rolled Mill (CRM) fines are very suitable candidate for low cost arsenic removal system. The chemical analysis of CRM fines shows the presence of 99.57% of Fe2O3. The rietveld analysis of X-ray diffraction pattern (FIG. 1) of these fines shows the peaks of only ferrous oxide (Fe2O3). This intern reveals that almost of 100% Fe2O3 is present in the fines.
The present invention further directed to an efficient arsenic removal system by using CRM fines with particle size are in the range of 100 to 300nm, where this fines of size 100 to 300nm are the waste product of CRM and know as CRM fines. The size analyses of these fines are observed by using Field Emission Gun-Scanning Electron Microscopy (FEG-SEM) (Fig.2).
In order to make the arsenic contaminated water for the purpose of experimentation, the appropriate amount of sodium arsenate (NaAsO2) salt dissolved in the water. Initially the 500ppb (0.5mg of As in one litre of water) solution made by adding 0.865 mg of sodium arsenate into one litre of water. Subsequently this solution stirred for 1-2 minutes to assure the complete and homogenous assimilation of sodium arsenate into water. The 200ppb and 70ppb of arsenic solution are made by adding the 1.5 litres and 6.1 litres of water respectively, in the initially a

made of arsenic solution (in 1 litre of water). The concentration of arsenic in water has confirmed by using Merck chemical (Merckoquant 117927) arsenic test kit.
The initial experiment for arsenic removal test is carried out by taking one litre of 200ppb arsenic (As3+) contaminated water solution. Subsequently 100-200 mg of CRM fines are added in the 200ppb arsenic contaminated water. The CRM fines arsenic contaminated water is stirred for 1-3 hours. The stirring exercise leads to the absorption of arsenic by CRM fines. The elements other then ferrous oxide present in CRM fines may be acting as a catalyst for oxidation of arsenite (As3+) and thus assisting ferrous oxide for the absorption of arsenic. The stirred CRM fines mixed arsenic contaminated water kept for 1-3 hours, which assure the settling of CRM fines. This water is filtered in 20-40 minutes by using a normal water filter candle which is mainly made of plaster of paris, sand and binder, to assure that the iron free water comes out from the filter. The arsenic concentration in filtered water has observed by using Merck chemical (Merckoquant 117927) arsenic test kit, which reveals the final concentration of arsenic in water is ~70ppb (Fig.3). 100-1000 mg of Cold Rolled Mill fines was added to reduce As3+ concentration from ~70ppb to ~0ppb arsenic contaminated water of one litre.
The final experiment for arsenic removal test is carried out by taking one litre of 70ppb arsenic (As3+) contaminated water solution. Subsequently preferably 100-200 mg of CRM fines are added in the 70ppb arsenic contaminated water. The CRM fines arsenic contaminated water is

stirred for 1-3 hours. The stirring exercise leads to the absorption of arsenic by CRM fines. The elements other then ferrous oxide present in CRM fines may be acting as a catalyst for oxidation of arsenite (As3+) and thus assisting ferrous oxide for the absorption of arsenic. The stirred CRM fines mixed arsenic contaminated water kept for 1-3 hours, which assure the settling of CRM fines. This water is filtered in 20-40 minutes by using a normal water filter candle which is mainly made of plaster of paris, sand and binder, to assure that the iron free water comes out from the filter. The arsenic concentration in filtered water has observed by using Merck chemical (Merckoquant 117927) arsenic test kit, which reveals the final concentration of arsenic in water is ~0 ppb (Fig.4).

WE CLAIM:
1. A method for the removal of arsenite (As3+) from arsenic contaminated
water comprising:
adding integrated steel industry Cold Rolled Mill fines to the contaminated water;
subjecting said water containing CRM fines to the step of stirring for 1 to 3 hours and subsequently allow to settle the CRM fines for 1 to 3 hours; filtering the water to produce decontaminated water.
2. The method as claimed in claim 1, wherein the 100-200 mg of Cold
Rolled Mill fines was added to reduce As3+ concentration from ~200ppb
to ~70ppb arsenic contaminated water of one litre.
3. The method as claimed in claim 1, wherein the 100-1000 mg
(preferable in the range of 100-200 mg) of Cold Rolled Mill fines was
added to reduce As3+ concentration from ~70ppb to ~0ppb arsenic
contaminated water of one litre.
4. The method as claimed in claim 1, wherein the water was filtered for 20-40 minutes by using a normal water filter candle made of plaster of paris, sand and binder to ensure that iron free water comes out from the filter.
5. The method as claimed in claim 1, wherein the particle size of the fines are in the range of 100-300nm.

6. The method as claimed in claim 1, wherein the said cold rolled mill (CRM) fines contain (~100%) Fe2O3.

A method for the removal of arsenite (As3+) from arsenic contaminated water comprising: adding integrated steel industry cold rolled mill fines to the contaminated water; subjecting said water containing CRM fines to the step of stirring for 1 to 3 hours and subsequently allow to settle the CRM fines for 1 to 3 hours; filtering the water to produce decontaminated water.

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Patent Number

279435

Indian Patent Application Number

671/KOL/2009

PG Journal Number

04/2017

Publication Date

27-Jan-2017

Grant Date

23-Jan-2017

Date of Filing

27-Apr-2009

Name of Patentee

TATA STEEL LIMITED

Applicant Address

RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831001

Inventors:

#	Inventor's Name	Inventor's Address
1	BHAGWATI PRASAD	TATA STEEL LIMITED, RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831001
2	CHIRADEEP GHOSH	TATA STEEL LIMITED, RESEARCH AND DEVELOPMENT AND SCIENTIFIC SERVICES DIVISION, JAMSHEDPUR 831001

PCT International Classification Number

C01B11/14

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA