Title of Invention

A PROCESS FOR REMOVAL OF ARSENIC FROM ARSENIC-CONTAMINATED WATER USING NANOSTRUCTURED POROUS ALUMINA POWDER AS ABSORPTIVE MEDIA

Abstract

A process for removing arsenic salt or arsenic compound from arsenic contaminated water using nanostructured porous alumina powder as an absorptive media comprises:- - a preparation of plurality of known concentrations of arsenic contaminated water; - agitation of these arsenic-contaminated water with a definite quantity of nanostructured porous alumina powder for a definite period using a stirrer to disperse the absorption media homogeneously or similar equipment for dispersion; - formation of an emulsion or slurry after agitation; - filtration of emulsion or slurry using a suitable filter paper or filter cloths or vacuum pump filtration; - collection of the filtered water; - determination estimation of arsenic concentration in the filtered water using both inductively coupled plasma-optical Emission spectroscopy (ICP-OES) and atomic absorption spectrophotometry (AAS) technique or suitable technique; and - estimation evaluation of arsenic removal in the contaminated water.

Full Text

FIELD OF INVENTION The present invention relates to a process for removing arsenic salts or arsenic compounds from arsenic-contaminated water to a level of 50 ppb or below using nanostructured porous alumina powder material as an absorptive media. More specifically, the present invention deals with an absorption process for removal of arsenic contaminants [both arsenic (III) and arsenic (V) species] from the raw water by treating arsenic contaminated water with nanostructured porous alumina material following various methods of absorption techniques, e.g., single-step absorption or multi-step absorption or bed-type absorption depending on the concentration of arsenic contaminants in the feed water and the level of removal. PRIOR ART One of the major concerns for sourcing potable water from natural resources is the possibility of arsenic contamination with the groundwater. In the various parts of the world, most notably, Bangladesh, India (West Bengal) and the United States of America have seen to cause life threatening diseases and other health hazards including cancer that affected a large numbers of people in the region due to consumption of arsenic contaminated water. About 3% of water samples collected worldwide showed to contain arsenic at concentrations greater than 50 'parts per billion' (ppb). Thermal water in Wyoming, California, Nevada, Alaska and Iceland are reported to be in the range of 20 - 3,800 ppb and water from the Waitopu Valley (New Zealand) is said to contain up to an alarming level of 276,000 ppb. Other countries include Argentina, Australia, Chile, China, Hungary, Mexico, Peru, Thailand etc, where adverse health effects have been documented due to arsenic contamination with the groundwater. -Z- The common route of exposure to arsenic is through food chain. Arsenic enters into groundwater in the form of its compounds or as soluble acids and further enters into the food chain containing plants, cereals and other food chains through rock and soil. Regions of volcanic or geothermal activity usually show elevated levels of arsenic contamination. Saltwater fishes often showed about 10 milligrams of arsenic per kilogram of tissue. The average daily per capita intake of arsenic from food could shoot up to a level of 50 micrograms, depending on geographical location. Though it is interesting to note that arsenic may rather be useful to human at extremely low doses, however, high consumption of arsenic is reported, commonly lead to gastrointestinal disorder, fatal skin diseases, hypotension, including cancer. Arsenic is a naturally occurring element that is tasteless and odorless. In the earth's crust, arsenic ranks as the twentieth most common element. Arsenic is present in soils ranging from 0.1 to 40 milligrams per kilogram (parts per million, ppm) with an average level between 1.5 - 2 milligrams per kilogram [1]. Arsenic is considered to be a metalloid and not a true metal. Arsenic exists in four valence states. The four states are: • Arsenate (As+5) • Arsenite (As+3) • Elemental Arsenic (As0) • Arsine gas (As3) In the groundwater, Arsenic is present predominantly in the form of arsenate (As+5) and arsenite (As+3). Of the two predominant species, the arsenite is considered to be more toxic than arsenate that also has higher solubility in water. Arsenite is generally associated with anarobic conditions in groundwater and is more mobile than arsenate in groundwater. Arsenite is reported to be around sixty times more toxic than arsenate, due to its preferred reaction with enzymes in human metabolism. Other examples of inorganic arsenic compounds found naturally include oxides of arsenic, i.e. -3- As203, As205 and sulfides of arsenic, i.e., As2S3, AsS, HAsS2, HAsS33". Arsenic compounds which are stable in oxygenated water include arsenic acid containing As (V) i.e. H3As04, H2As04", Has042", and As043~. Arsenous acid containing As (III) species is also stable as H3As03 and H2As03" under mild reducing aqueous solutions. Arsenite can be converted to arsenate under oxidizing atmosphere, which means well-aerated surface water predominately contains arsenates. A wide range of technologies has been tried for the removal of arsenic from the borewell or groundwater containing higher levels of arsenic, thus making the natural water potable. The most common technologies for removal of arsenic utilize the conventional processes of oxidation, precipitation, ion exchange processes, membrane filtration techniques and most widely adsorption processes using various adsorptive media. These techniques are discussed in the following examples: A. Oxidative Methods Arsenic is present in groundwater in As (III) and As (V) forms in different proportions. Most oxidative treatment methods are effective in removing arsenic in pentavalent form and hence include an oxidation step for converting arsenite to arsenate, in case arsenic (III) is present in the water. Arsenite can be oxidized by oxygen, ozone, free chlorine, hypochlorite, permanganate, hydrogen peroxide, and Fenton's reagent, though atmospheric oxygen, hypochloride and permanganate are commonly used. The corresponding chemical reactions involved in oxidation process could be written as: H3As03 + V2 02 D H2As04" + 2H+ H3As03 + HCIO □ HAs04' + CI" + 3H+ 3H3As03 + 2KMn04 □ 3HAs04"2 + 2Mn02+ + 2K+ + 4H+ + H20 Arial oxidation of arsenic is very slow and can take several weeks for oxidation but chemicals like chlorine and permanganate can rapidly oxidize arsenite under wide range of conditions [5]. Al. In-situ Oxidation In-situ oxidation, the dissolved oxygen in water oxidizes arsenite to less mobile arsenate that results in reduction of arsenic content in water. Experimental results show that arsenic in the tube well water following in-situ oxidation is reduced to about half due to underground precipitation and adsorption on ferric iron [5]. A2. Solar Oxidation Solar oxidation is another simple example of oxidative method to oxidize arsenic in presence of solar radiation. By using this method, even transparent bottles containing arsenic contaminated water when exposed to sunlight for a given period of time is reported to reduce arsenic (III) content in the water. Ultraviolet radiation can also catalyze the process of oxidation of arsenite in presence of other oxidants like oxygen. Experiments using natural water in Bangladesh region show that the process, on average, can reduce arsenic content of water to about one-third [6], A3. Oxidation Method by Passive Sedimentation Passive sedimentation is another example of oxidative method that had received considerable attention primarily because of rural people's habit of storing water in pitchers for drinking purposes. Oxidation of water during collection and subsequent storage in houses often cause a reduction in arsenic concentration in the stored water. Experiments conducted using groundwater collected from the region of Bangladesh showed zero to high reduction in arsenic content by passive sedimentation. Arsenic reduction by plain sedimentation, appears to be dependent on water quality, particularly, the presence of precipitating iron in water that makes the arsenic to sediment under static condition of storage along with iron. Authors [5] showed that more than 50% reduction in arsenic content is possible by sedimentation of tube-well water containing 380-480 - 5- mg/L of alkalinity in the form of CaC03 and 8-12 mg/L of iron, but the desired level of arsenic could not be reduced by this process. Most studies showed a reduction of 0 - 25% of the initial concentration of arsenic in ground water by this method. B. Precipitation and coagulation methods Precipitation and coagulation methods for arsenic removal from raw water depend upon the co-precipitation of both water insoluble arsenates and inorganic oxides of other metals. The water insoluble inorganic oxides are produced by the hydrolysis in the arsenic contaminated raw water by adding coagulants such as alum, ferric chloride or ferric sulfate. It is reported that in case of alum as coagulant, the pH of the contaminated water must be very close to neutral, whereas in case of ferric chloride, it can serve over a wide pH range. Bl. Filtration followed by Coagulation Conventional filtration followed by coagulation or flocculation using iron salts, is reported to be effective in removing arsenic up to 90% of (As+5) and 50% of (As+3).at pH in or around 7. Thus, in such methods, it is very important to fully oxidize As+3 to As+5 with chlorine or another strong oxidant prior to coagulation. It was reported [7] that coagulation/ filtration for arsenic removal from a high arsenic water with ferric ions as the coagulant could be considerably enhanced by adding an appropriate amount of coarse calcite. The enhanced coagulation and conventional filtration achieved a very high arsenic removal over 99%. Another report [8] states that, electro-coagulation is a very promising electrochemical treatment technique that does not require the addition of -6- chemicals or regeneration. The solid products which were deposited on the iron electrode during the process of electro-coagulation were characterized. The results suggested that magnetite particles and amorphous iron oxy- hydroxides present in the electro-coagulation products remove As(III) and As(V) with an efficiency of more than 99% from ground water in a field pilot scale study. C. Adsorption Methods Adsorption methods have been successfully applied to remove arsenic from groundwater. Adsorptive media that have been most widely used are activated alumina, ion exchange, elemental iron or iron compounds like ferric hydroxide, organic polymers, kaolin clay, and silica sand. Granular Ferric Hydroxide (GFH) is reported to be a good absorptive material. A lot of research has been carried out using this material for absorption. The article [9] describes the quantification of arsenate adsorption kinetics on GFH and to determine the inter particle diffusion rate. In another report, it is stated [10] that GFH is effective in reducing both As (III) and As (V) to a level less than 5 ppb in drinking water from an initial concentration of 100 ppb at the pH levels of 6 and 7.6, with highest removal recorded at pH 7.6. It has been reported [11] that arsenic adsorption by GFH in a fixed bed reactor is simple, safe, and effective method for the elimination of arsenic from contaminated ground water. Depending upon the concentration of arsenic in raw water, 50,000 to 70,000 bed volumes can be treated with GFH. CI. Absorption using Activated Alumina Activated alumina has a long history of using as an adsorptive material for arsenic removal. The material is extremely porous and has a high surface area. The capacity of arsenic removal by activated alumina is pH dependent, with the maximum removal capacity achieved in the pH range of 5.5 - 6. It is reported [14] that a household technology is developed based on activated alumina in which the efficiency of the technology is reported to be excellent irrespective of feed water quality. As reported, it also removes iron and manganese besides removal of As. The two activated alumina plants evaluated were capable of achieving arsenic levels of 5 ppb or less in the treated water, provided that the activated alumina was changed in time [12]. It is reported [15] that arsenic removal can be done to the acceptable levels of below 50 ppb within 2 hours of adsorption time. It is achieved by agitation in the presence of activated alumina adsorbent below about 200 micrometers diameter with sufficient porosity of pores of above 100A diameter. It is reported that the amount of activated alumina adsorbent used per liter should not exceed 3.5gm because higher amounts results in higher viscosity and hence requiring higher energy consumption for mixing, pumping, etc., in higher consumption and possibly higher losses of alumina. It is preferred to use adsorbent in the range of 1.0-3.5 gm/L to facilitate solid-liquid contact and separation of loaded adsorbent. The said adsorption process is suitable for reducing levels of arsenic of about 0.5 to 5 ppm to below the acceptable limit of 50 ppb. The feed water having concentrations above 5 ppm, a pretreatment which includes precipitation with reagents such as ferric sulphate or chloride, is preferably used to reduce the arsenic concentration. Another group [16] has tried to remove arsenite ions (As (III)) by activated alumina. The effect on adsorbent dose, solution pH, and contact time has been investigated that revealed arsenite removal is pH and temperature dependent. A maximum of 96.2% As (III) removal could be achieved at pH 7.6. The results suggested that adsorption of As (III) on activated alumina is a complex mechanism where both surface adsorption and intra particle diffusion contribute to the rate determining step and the adsorption process was spontaneous and decreased with increase in temperature. C2. Absorption using metallic iron Metallic iron or zero-valent iron is an effective material for dehalogenation of chlorinated organic compounds and for the removal of toxic metals [17]. Granular iron is reported to offer a great promise for the in situ remediation of ground water contaminated with organic and inorganic pollutants. Thermodynamic considerations indicate that Fe (0) can reduce highly soluble As (V) and As (III) to sparsely soluble As (0). It has been reported that batch experiments showed faster removal of As (III) than As (V) removal rate at pH 4 and 7 under anoxic conditions and under oxic conditions, As (III) removal was slower than As (V) removal at pH 7. Another article [18] reported a two stage treatment approach, viz. treatment with Fenton's reagent (lOOmg of ferrous ammonium sulphate + 100 pi H2O2 per liter) for 10 min followed by passing through iron scrap and filtering through sand, was found to be suitable for consistently producing water with arsenic content less than 10 ppb. D. Membrane Filtration Methods Membrane filtration methods have been applied primarily to purify brackish water or seawater for use as drinking water. The water flows through the membrane whereas most of the water contaminants are retained. Not only are inorganic contaminants such as arsenic, lead, and iron removed from the treated water, but pathogens and hazardous organic contaminants are removed. Some articles have been reported to separate arsenic by various membrane filtration methods. Dl. Reverse Osmosis (RO) Most reverse osmosis plants are designed for 75-80% recovery, i.e. up to 25% of the flow must be disposed of as a concentrated, possibly hazardous, and waste. Reverse osmosis is quite capable of the removal of arsenic to very low levels. Robert Y. Ning [19] has done work on arsenic removal by RO method. Arsenic in the commonly high oxidation states of (V) is very effectively removed by RO. But it shows lower treatment efficiencies for arsenite. Elevating the pH such as by caustic injection into RO system feed water is done for the greater removal of As (III) compounds. It has been reported [20] that removal of As (V) and Sb (V) is much higher than As (III) and Sb (III) over the pH range 3-10. The effect of solution pH on the removal of arsenic using RO membranes was strongly affected by the solution pH, especially As (III). Controlling the pH of membrane feed water is essential for the successful removal of arsenic compounds. D2. Nano-Filtration This process uses an ultra-low-pressure membrane designed to allow only passage of particles less than 1 nanometer (10 Angstroms) in size. It is thus very efficient in the removal of dissolved matter, but is, of course, not selective for arsenic only. Like all other membrane processes, extensive pretreatment is necessary to prevent fouling of the delicate and expensive membranes caused by particulate matter, scaling, or bio-fouling. The rejection characteristics of the sodium dibasic arsenate as well as the arsenate anion from the natural groundwater by the nano-filtration membranes have been reported [21] to be satisfactory. Another report [22] have compared the performance of rapid sand filtration inter-chlorination system with nano-filtration in arsenic removal from raw water. It was observed that nano-filtration membrane could remove over 95% of As (V) under relatively low applied pressure and 75% of As (III) without adding any chemical additives. It was observed that As (III) could not be removed by rapid sand filtration system with out pre-oxidation of As (III) to As (V). D3. Electro dialysis (ED) and Electro Dialysis Reversal CEDRI Electro-dialytic and dialytic techniques [23] were used for the removal of Arsenic and other heavy metals. The effect of applying direct current, as "cleaning agent", of up to 120 mA was investigated. Parallel comparisons -10- were done between the two processes to reveal transport of charged particles induced solely by internal electrochemical potential difference in the system. The maximum removal efficiencies obtained in a batch electro-dialytic cell operated for 14 days was 95% for Arsenic. D4. Coagulation-Assisted Membrane Process ("CAMP*) Coagulation-assisted membrane process (CAMP) is considered to be a promising technology for arsenic removal because it can be applied over a wide range of water quality that contains high turbidity, iron, manganese, sulfate and nitrate. Low pressure membranes (e.g. micro-filtration and ultra-filtration) are very effective in removing particulate arsenic, but with out pre-coagulation step, low pressure membranes are ineffective at removing soluble arsenic. Metal- based coagulants, such as ferric chloride, can be used to bind arsenic which is removed with the ferric floe on the membrane. Factors affecting the CAM process include ferric chloride dosage, pH, mixing and floe formation. As with all membrane processes, provision for adequate pretreatment to control feed water quality need to be taken to protect the membrane from fouling caused by particulate matter, scaling and bio-fouling to optimize membrane performance and life. Disposal of the reject coagulant can be to a sanitary sewer. E. Ion Exchange Methods One great advantage of Ion Exchange is that no pH adjustment is necessary and recent advances in resin technology have replaced the weak-base anion resins with strong-base ones. Pentavalent arsenic (As+5), being present as the divalent anion HAs04"2, appears to have greater affinity for this type of resin. The ability to consistently achieve low levels of arsenic in the treated water (i.e. new anion exchanger (AE) prepared from a natural material like coconut coir pith (CP), for the removal of arsenic (V) from the aqueous solutions was evaluated [13]. The adsorbent (CP-AE) carrying dimethylaminohydroxypropyl weak base functional group was synthesized by the reaction of CP with epichlorohydrin and dimethylamine followed by treatment of hydrochloric acid. Analysis shows the presence of -NH+(CH3)2CI" group in the adsorbent and confirms the decrease in crystallinity in CP-AE compared to CP. Batch experiments were conducted to examine the efficiency of the adsorbent on As(V) removal and maximum removal of 99.2% was obtained. It appears from the literature that absorption methods using appropriate absorptive media and preferably without the usage of any secondary material/s (those normally used to optimize pH in the absorption process for enhancing the absorption) could be a better solution for removing arsenic from raw water. In this context, this invention was made using a porous material based on aluminum oxide ceramic powder sourced from Bharat Heavy Electricals Limited, India (BHEL/CTI) [24] that removes arsenic to a level of 50 ppb or below from feed water containing arsenic in the range of 10 - 500 'parts per million' (ppm). The process does not need to use any secondary chemical/s in the absorption process. The process hereby discloses various parameters that effect the absorption process, i.e., the quantity of absorbent media, agitation/residence time, type/mode of absorption (single-step, multi-step, bed type etc) for effective removal arsenic from feed water having variable levels of arsenic in absence of any secondary chemical/s in the absorption process those normally used to optimize the pH of the medium for enhancing the absorption. OBJECTS OF THE INVENTION It is therefore an object of the present invention to propose a process for removing arsenic salts or arsenic compound from arsenic-contaminated waters to a level of 50 ppb or below using nano structured porous alumina power material as an absorptive media by which arsenic-free water could be generated from arsenic-contaminated water that will help the society at large -12- for prevention of many diseases and health hazards those caused by consumption of arsenic-contaminated potable water. Another object of the present invention is to propose a process for removing arsenic compounds from arsenic contaminated water to a level of 50 ppb or below using nano structructed porous alumina power material which is economical and environmentally benign material less costly and eco-friendly. DESCRIPTION OF THE PROCESS: In arsenic-contaminated groundwater, both arsenic (V) and arsenic (III) could predominantly be present, the invented process is valid for any raw water that is contaminated with either or both the above forms of arsenic. Arsenic contaminated water with variable concentrations of both (V) and (III) forms of arsenic were prepared by dissolving known quantities of arsenic salts, i.e., sodium arsenate (Na2HAsC>4.7H20) and sodium arsenite (NaAs02) respectively in de-ionized water. Both of the salts are soluble in water and are the salts largely used for making an artificial contamination of arsenic in water under laboratory condition. The derived arsenic-contaminated water represents a condition, similar to various sources of raw water from natural sources with respect to arsenic contamination/s. As (V) contaminated water, i.e., aqueous solutions of sodium arsenate (Na2HAs04.7H20) (AR grade) is prepared with known concentrations of i) 500 ppm (0.500mg/L), ii) 300 ppm (0.300mg/L), iii) 100 ppm (O.lOOmg/L), iv) 50 ppm (0.050mg/L), v) 20 ppm (0.020mg/L) and vi) 10 ppm (O.OlOmg/L). In case of As (III) contaminated water, i.e., aqueous solutions of sodium arsenite (NaAs02) (AR grade) is prepared with the same concentrations are prepared in the above. -13- As per the process, arsenic contaminated water with varied levels of arsenic is agitated with definite quantity of nanostructured porous alumina powder (absorptive media) in a definite period of time using a magnetic stirrer. The purpose of agitation is to allow arsenic to get absorbed with the absorptive media within a definite period of agitation time. The purpose of stirring is to disperse the absorptive media homogeneously in the arsenic contaminated water and the speed of stirring could be adjusted accordingly so as to disperse the absorptive media homogeneously throughout the water. Both the agitation and dispersion operation in the above process could also be achieved by other means, say, ultrasonic treatment. After the agitation, an emulsion or slurry is resulted which needs to be filtered using suitable filter paper or filter cloth. In order to accelerate the filtration process, a vacuum pump could be used. After filtration, the filtered water is collected and arsenic concentration in the filtered water is estimated using both Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Atomic Absorption Spectrophotometry (AAS) techniques and removal of arsenic in the contaminated water is estimated. It is to be mentioned that when the evaporation takes place from the filtered water, the concentration of arsenic in the filtered water would go up that would mislead the arsenic level in the filtered water and hence the removal efficiency of the process. For the purpose of accurate testing, the filtered water is preserved carefully to avoid any evaporation or contamination that could take place due to environmental and atmospheric conditions. In case the removal of arsenic in desired level has not been achieved by the said agitation process, one way to achieve this is to increase the quantity of absorptive media and follow thereafter the same procedure. Alternatively, the number of steps in the agitation process need to be progressively increased using fresh absorptive media, until the level of separation of arsenic is achieved in the filtrate and hence a so-called multi-step absorption method could be followed. Further methods of achieving the desired level of arsenic in the filtrate besides agitating the absorptive media either in a single-step or multi-step process, absorption of arsenic by the absorptive media is also adopted by making a bed using the absorptive media with required thickness that is wrapped with a filter cloth in which the arsenic contaminated water is passed through the bed and thereby the filtered water is collected in the other end of the bed. Due to the high retention time of the arsenic contaminated water in the absorptive bed, a high adsorption of arsenic is observed and arsenic is removed in the desired level from the feed water. Table 1: Removal of arsenic ion from feed water TASfV^I using 0.005 gm/cc of absorptive media which is agitated for 30 min by single- step abortion process Sample Initial concentration Final concentration 1 217 ppm 169.4 ppm 2 117.3 ppm 103 ppm 3 46 ppm 29.55 ppm 4 18.7 ppm 10.85 ppm 5 7.2 ppm 0.86 ppm 6 4.23 ppm 0.06 ppm -15- Figure 1: Comparison of initial and final concentration of Arsenate ion [As (V)] in ppm for 0.5 gm of adsorbent/100 ml of arsenic-contaminated water, which is agitated for 30 min TABLE 2: Removal of arsenic ion from feed water fAsfV)1 using 0.01 qm/cc absorptive media bv single-step absorption process which is agitated for 30 min Sample Initial concentration Final concentration 1 227.9 ppm 180.54 ppm 2 117.3 ppm 104.06 ppm 3 46 ppm 25.3 ppm 4 18.7 ppm 5.8 ppm 5 7.2 ppm 0.05 ppm 6 4.23 ppm 0.2 ppm - lb" Figure 2: Comparison of initial and final concentration of arsenate ion [As (V)] in ppm for 1.0 gm of adsorbent/100 ml of arsenic-contaminated water, which is agitated for 30 min TABLE 3: Removal of arsenic ion from feed water rAsflll)! using 0.005 qm/cc of absorptive media by single-step absorption process which is agitated for 30 min Sample Initial concentration Final concentration 1 367 ppm 298.6 ppm 2 193.72 ppm 173.1 ppm 3 93 ppm 74.02 ppm 4 28.3 ppm 24.87 ppm 5 13.1 ppm 10.25 ppm 6 8.81 ppm 7.08 ppm -17- Figure 3: Comparison of initial and final concentration of arsenite ion [As (III)] in ppm for 0.5 gm of adsorbent/100 ml of arsenic-contaminated water which is agitated for 30 min TABLE 4: Removal of arsenic ion from feed water fAsfllDl using 0.01 qm/cc of absorptive media bv single-step absorption process which is agitated for 30 min Sample Initial concentration Final concentration 1 367 ppm 303.85 ppm 2 193.72 ppm 187.04 ppm 3 93 ppm 75.03 ppm 4 28.3 ppm 26.34 ppm 5 13.1 ppm 10.47 ppm 6 8.81 ppm 5.15 ppm -IS- Figure 4: Comparison of initial and final concentration of arsenite ion [As (III)] in ppm for 1.0 gm of adsorbent/100 ml of arsenic-contaminated water which is agitated for 30 min TABLE 5: Removal of arsenic ion from feed water TAsfV^I using 0.005 am/cc of absorptive media bv step absorption process which is agitated for 30 min Adsorbent (gm)/100 ml Filtration time (min) / Step As[V] (ppm) Before As[V] (ppm) After 0.5 30 / 1 Step 227.9 198 0.5 30 / 2 Step 227.9 177 0.5 30 / 3 Step 227.9 162 -11' TABLE 6: Removal of arsenic ion from feed water rAsflllll using 0.005 am/cc absorptive media by step absorption process which is agitated for 30 min Adsorbent (gm)/100 ml Filtration time (min) / Step As[III](ppm) Before As[III](ppm) After 0.5 30 / 1 Step 361.3 331 0.5 30 / 2 Step 361.3 304 0.5 30/3 Step 361.3 288 TABLE 7: Removal of arsenic ion from feed water TAsOm using 1 am of adsorptive media by bed adsorption process Initial As(V) Concentration (ppm) Final As(V) Concentration (ppm) 4.23 0.02 TABLE 8: Removal of arsenic ion from feed water fAsCIim using -20' 1 qm of adsorptive media by bed adsorption process Initial As(III) Concentration (ppm) Final As(III) Concentration (ppm) 8.81 -If- A process for removing arsenic salt or arsenic compound from arsenic contaminated water using nanostructured porous alumina powder as an absorptive media comprises:- - a preparation of plurality of known concentrations of arsenic contaminated water; - agitation of these arsenic-contaminated water with a definite quantity of nanostructured porous alumina powder for a definite period using a stirrer to disperse the absorption media homogeneously or similar equipment for dispersion; - formation of an emulsion or slurry after agitation; - filtration of emulsion or slurry using a suitable filter paper or filter cloths or vacuum pump filtration; - collection of the filtered water; - determination estimation of arsenic concentration in the filtered water using both inductively coupled plasma-optical Emission spectroscopy (ICP-OES) and atomic absorption spectrophotometry (AAS) technique or suitable technique; and - estimation evaluation of arsenic removal in the contaminated water.

Documents:

00552-kol-2008-abstract.pdf

00552-kol-2008-claims.pdf

00552-kol-2008-correspondence others.pdf

00552-kol-2008-description complete.pdf

00552-kol-2008-form 1.pdf

00552-kol-2008-form 2.pdf

00552-kol-2008-form 3.pdf

00552-kol-2008-gpa.pdf

552-KOL-2008-(23-01-2012)- CLAIMS.PDF

552-KOL-2008-(23-01-2012)-DESCRIPTION (COMPLETE).pdf

552-KOL-2008-(23-01-2012)-EXAMINATION REPORT REPLY RECIEVED.PDF

552-KOL-2008-(23-01-2012)-FORM 1.pdf

552-KOL-2008-(23-01-2012)-FORM 2.pdf

552-KOL-2008-(23-01-2012)-OTHERS.pdf

552-KOL-2008-(27-07-2012)-CORRESPONDENCE.pdf

552-KOL-2008-CLAIMS.pdf

552-KOL-2008-CORRESPONDENCE 1.1.pdf

552-KOL-2008-CORRESPONDENCE.pdf

552-KOL-2008-DESCRIPTION (COMPLETE).pdf

552-KOL-2008-EXAMINATION REPORT 1.1.pdf

552-KOL-2008-EXAMINATION REPORT.pdf

552-KOL-2008-FORM 1.pdf

552-KOL-2008-FORM 18 1.1.pdf

552-kol-2008-form 18.pdf

552-KOL-2008-FORM 2.pdf

552-KOL-2008-FORM 3 1.1.pdf

552-KOL-2008-FORM 3.pdf

552-KOL-2008-GPA 1.1.pdf

552-KOL-2008-GPA.pdf

552-KOL-2008-GRANTED-CLAIMS.pdf

552-KOL-2008-GRANTED-DESCRIPTION (COMPLETE).pdf

552-KOL-2008-GRANTED-FORM 1.pdf

552-KOL-2008-GRANTED-FORM 2.pdf

552-KOL-2008-GRANTED-SPECIFICATION.pdf

552-KOL-2008-REPLY TO EXAMINATION REPORT 1.1.pdf

552-KOL-2008-REPLY TO EXAMINATION REPORT.pdf

552-KOL-2008-SPECIFICATION.pdf