WO2012011856A1 - Composition for removal of arsenic - Google Patents

Composition for removal of arsenic Download PDF

Info

Publication number
WO2012011856A1
WO2012011856A1 PCT/SE2010/050864 SE2010050864W WO2012011856A1 WO 2012011856 A1 WO2012011856 A1 WO 2012011856A1 SE 2010050864 W SE2010050864 W SE 2010050864W WO 2012011856 A1 WO2012011856 A1 WO 2012011856A1
Authority
WO
WIPO (PCT)
Prior art keywords
water
arsenic
composition
zeolite
iron
Prior art date
Application number
PCT/SE2010/050864
Other languages
French (fr)
Inventor
Ferenc LÓNYI
János PAPP
József Valyon
József VÁRI
Original Assignee
Josab International Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Josab International Ab filed Critical Josab International Ab
Priority to PCT/SE2010/050864 priority Critical patent/WO2012011856A1/en
Publication of WO2012011856A1 publication Critical patent/WO2012011856A1/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/288—Treatment of water, waste water, or sewage by sorption using composite sorbents, e.g. coated, impregnated, multi-layered
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/0203—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of metals not provided for in B01J20/04
    • B01J20/0225—Compounds of Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt
    • B01J20/0229—Compounds of Fe
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B01J20/08—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04 comprising aluminium oxide or hydroxide; comprising bauxite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/16—Alumino-silicates
    • B01J20/18—Synthetic zeolitic molecular sieves
    • B01J20/186—Chemical treatments in view of modifying the properties of the sieve, e.g. increasing the stability or the activity, also decreasing the activity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28004—Sorbent size or size distribution, e.g. particle size
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28052—Several layers of identical or different sorbents stacked in a housing, e.g. in a column
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/103—Arsenic compounds

Definitions

  • the present invention relates to a composition for removal of arsenic from water, a method for producing a composition for removal of arsenic from water, and a method for removal of arsenic from water.
  • Arsenic is a highly toxic element, having frequent occurrence in nature. Numerous arsenic-containing minerals are known, and most of them are arsenides, arsenates, arsenites and sulfides. Arsenic content of ground and surface water can mostly be related to soil pollution from agriculture and industry. Water from bedrock wells can be contaminated by arsenic, dissolved from pyrogenic and sedimentary rocks. Ingested arsenic can cause lung, kidney, liver, skin, or bladder cancer; cardiovascular diseases; and neurological damage. Because of the toxicity of arsenic the Hungarian Government (201/2001 . (X. 25.) Gov. Legislation) in accordance with other national (e.g.
  • arsenic is present in organic and inorganic compounds.
  • the dominant forms of arsenic are the inorganic arsenite anion, containing arsenic in As(lll) form; or arsenate anion, containing arsenic in As(V) form.
  • Oxidative environments favors the formation of arsenate, while reductive environments favours the arsenite in anionic form.
  • the charge of the anion depends on pH, but cannot exceed three.
  • Currently applied technologies for treatment of potable or waste water connect arsenic removal with iron and manganese removal. Iron and manganese pollutants are chemically oxidized and the resulting precipitate is filtered.
  • the amount and surface area of iron-containing precipitates, active as arsenic adsorbing flocculants, can be increased by further addition of iron salts.
  • iron salts By the hydrolysis of iron salt arsenic adsorbing iron hydroxides are formed. Precipitation and adsorption can be enhanced by addition of lime milk.
  • Arsenites may be oxidized to better adsorbing arsenates by addition of manganese salts.
  • Arsenic free water can be produced by the filtration removal of arsenic containing precipitates. However, complete removal of arsenic-containing colloidal particles, such as precipitates, is difficult. Filtration is usually performed on packed columns filled with sand or by membrane separation. Although oxidation/coagulation-flocculation/filtration may decrease the arsenic content of water, arsenic concentration below 10 ppb can generally not be achieved. Thus, there is a need for more efficient techniques concerning removal of arsenic from water.
  • Adsorbents for arsenic removal are metallic iron, activated alumina, activated carbon, red mud, coconut shell, rice-bran and zeolites.
  • the arsen ic adsorption capacity and selectivity of the above mentioned materials are too low. Thus there is a need for more efficient adsorbents for arsenic removal from water.
  • Iron(lll) oxides have higher adsorption capacities than the above mentioned adsorbents.
  • the documents DE 4320003, US 6 809 062 and US 6 849 187 relates to production of grained or granulated iron(lll) oxides, for arsenic removal.
  • Other existing adsorbents include amorphous or partly crystalline, hydrated iron(lll) oxide (FeOOH) or goethite (a-FeOOH) available under different trademarks such as AdsorpAs, Bayoxide E33, es GEH 33.
  • the US patent with number US 7 314 569 discloses adsorbents of iron oxyhydroxide microcrystals, such as akaganeite ( ⁇ -FeOOH) bound to a zeolite surface.
  • adsorbents of iron oxyhydroxide microcrystals such as akaganeite ( ⁇ -FeOOH) bound to a zeolite surface.
  • ⁇ -FeOOH akaganeite
  • zeolites mainly natural zeolites is widespread in water cleaning as ion-exchanger or filtration material.
  • Zeolites are ion-exchanged by iron-salts (US 6 042 731 , US 747631 1 ), iron-hydroxides are precipitated on the zeolite surface (US 6 790 363; C.-S. Jeon et. al.: Adsorption characteristics of As(V) on iron-coated zeolite. J. Hazard. Mater. 163 (2009) 804-808.), or iron oxyhydroxide microcrystals, like akaganeite ( ⁇ -FeOOH) are bound to the zeolite surface (US 7 314 569).
  • Al is synonumos with aluminum.
  • Si is synonumos with silicon.
  • Fe is synonumos with iron.
  • One objective of the present invention is to provide an efficient composition for removal of arsenic from water without disadvantages associated with known techniques, as well as a method for producing such compositions and a method for removal of arsenic from water using such compositions.
  • the objective is realised by means of a composition for removal of arsenic from water, the composition
  • adsorbent comprising an adsorbent and a carrier, characterized by the adsorbent comprising an oxyhydroxide comprising Fe, and Al and/or Si, and
  • the carrier comprising zeolite, wherein the adsorbent being chemically bonded to the zeolite.
  • Arsenic is intended to comprise any compound containing arsenic suitable for removal from water by the composition according to the invention.
  • Arsenic may be selected from the group comprising elemental arsenic, arsenic present in organic compounds, arsenic present in inorganic compounds, inorganic arsenite anion containing arsenic in As(lll) form, arsenate anion containing arsenic in As(V) form, and mixtures thereof.
  • An adsorbent comprising oxyhydroxides is efficient for interaction with arsenic containing compounds.
  • the oxyhydroxide comprising Fe and Al and/or Si results in efficient interaction with arsenic containing compounds. Further, high equilibrium and dynamic arsenic adsorption capacity may be obtained with such a composition according to the invention.
  • the oxyhydroxide comprising Fe and Al and/or Si is a mixed oxyhydroxide with resulting efficient removal of arsenic from water when used for such purpose.
  • the adsorbent being chemically bonded to the zeolite results in a strong link between the adsorbent and the carrier.
  • the composition comprising an adsorbent and a carrier results in a mechanically stable composition. Further, a particulate composition may be obtained. Yet further, efficient handling and use of the composition is allowed, for example by packing the composition in a column. Such a composition may be efficient for removal of arsenic from water.
  • Such particulate compositions may efficiently be removed from water after treatment of water by removal of arsenic from the water, for example by filtration or sedimentation of the composition from the treated water.
  • Such compositions according to the invention may be suitable for the economical production of drinking water containing arsenic lower than 10 ppb
  • Zeolite may provide for an inexpensive adsorbent material which may be efficiently disposed, for example as non-hazardous landfill.
  • the oxyhydroxide may be a polyoxyhydroxide.
  • Said Fe, and Al and/or Si may be linked by -O- bridges, and the oxyhydroxide may comprise terminal OH-groups.
  • the polyoxyhydroxide may be a compound consisting of the elements Fe and Al and/or Si, wherein each element is linked to one, two or three elements by an oxygen bridge.
  • Each element may bind 0, 1 , or 2 hydroxyl groups, such that each element binds a total of three groups including hydroxyl groups and other elements via oxygen bridge.
  • the molar ratio of Fe to Si; Fe to Al; or Fe to Si and Al; may be above 1 .
  • the adsorbent and/or the oxyhydroxide may contain more Fe than the total amount of Al and Si, on a molar basis. Such a ratio results in efficient adsorbents and removal of arsenic. It may be preferred that the molar ratio of Fe to Si; Fe to Al; or Fe to Si and Al is above 3. Thus, an even more efficient adsorbent may be obtained and even more efficient removal of arsenic may be realized.
  • the composition may be in the form of granules smaller than 5 mm. Such sizes of granules of the composition may result in efficient removal of arsenic and desirable properties for removal of arsenic when the composition is packed in columns. Further, such sizes may efficiently be obtained by sieving. It may be preferred that the composition is in the form of granules smaller than 1 .41 mm, and most preferably between 0.5 and 1 .41 mm. Such preferred sizes may result in highly efficient removal of arsenic from water.
  • the objective is realized by a method for producing a composition for removal of arsenic from water, comprising the steps of: providing iron salt and optionally aluminum salt;
  • particulate zeolite obtaining a suspension of said iron salt and optionally aluminum salt and said particulate zeolite; providing said
  • suspension with a basic solution; optional mixing of the suspension with the basic solution; allowing chemical reaction to take place, producing a composition comprising oxyhydroxide, which oxyhydroxide comprises Fe, and Al and/or Si, chemically bonded to zeolite; collecting said composition.
  • oxyhydroxide which oxyhydroxide comprises Fe, and Al and/or Si, chemically bonded to zeolite
  • Preferred basic solutions are basic solutions of silicate and/or alkali hydroxide solutions, e.g. an sodium hydroxide solution.
  • Iron salt and optionally aluminum salt may be efficient starting materials for producing of the composition.
  • Obtaining a suspension of said iron salt and optionally aluminum salt and said particulate zeolite may be an efficient means for impregnating the zeolite with iron, and thus further to obtain efficient reaction between the iron and the zeolite.
  • Providing said suspension with a basic solution may result in that Fe(lll)(OH)3 is formed from the iron, and if the basic solution is a basic solution of silicate to provide Si-ions and/or Si(OH)3. Mixing of said suspension may make the chemical reaction to be efficient. Allowing chemical reaction to take place may result in chemical bonds are being formed such that iron is linked to zeolite via an oxygen bridge. Further it may allow condensation reactions to take place such that oxyhydroxides are formed comprising Fe, and Al and/or Si. Further, the oxyhydroxide may via condensation reaction be bonded to the zeolite.
  • the chemical reaction thus results in the composition according to the invention comprising adsorbent comprising oxyhydroxide chemically bonded to the carrier comprising zeolite.
  • Collecting said composition allows for further use of the composition.
  • the step of allowing chemical reaction may be followed by removal of alkali salts by washing with water.
  • concentration of alkali salts in solution with the composition is reduced.
  • Said iron salt may be iron(lll)chloride and said aluminium salt may be aluminium(lll)chloride.
  • Such salts may be efficient for producing the composition according to the invention.
  • the basic solution may be an alkali hydroxide solution, preferably a sodium hydroxide solution.
  • the basic solution of silicate may be an aqueous solution of Na2SiO2(OH) 2 and alkali hydroxide, preferably NaOH, or S1O2 and alkali hydroxide, preferably NaOH. Such a solution may be effient for the invention.
  • the chemical reaction may involve forming an oxygen bridge between the oxyhydroxide and the zeolite. Thus, efficient and suitable bonds may be obtained between the adsorbent and the carrier.
  • the chemical reaction may involves hydroxyl group of the zeolite.
  • the objective is achieved by a product obtainable by said method for removal of arsenic from water.
  • a product is efficient for removal of arsenic from water.
  • the objective is achieved by a method for treatment of water containing arsenic, wherein said composition is contacted with the water and is allowed to adsorb arsenic from the water.
  • arsenic dissolved or in other ways present in the water may be removed from the water by being adsorbed to the composition.
  • Said method for treatment of water may further comprise the step of separating the composition with adsorbed arsenic and the treated water.
  • arsenic may be removed from the vicinity of the water. Further the arsenic may be deposited away from the water.
  • the treated water from said method of treatment of water may contain less than 10 ppb of arsenic. Thus very low concentration of arsenic in the treated water may be obtained.
  • the water in the method for treatment of water according to the invention may be ground water, river water, industrial waste water, civic waste water, potable water and/or surface water.
  • Figure 1 illustrates arsenic breakthrough curves of adsorbents.
  • One embodiment of the present invention involves condensation reaction occuring between hydroxyl groups of the zeolite and hydroxyl groups of the Fe-hydroxide.
  • the Fe-hydroxide is co-precipitated in the presence of the zeolite with Si-hydroxide and/or Al-hydroxide.
  • mixed oxyhydroxide polymers comprising Fe and Al and/or Si, chemically bound to zeolite support, and mixed oxyhydroxides comprising Fe and Al and/or Si particles not being bound to zeolite are formed.
  • the formation of the oxyhydroxides chemically bound to the zeolite is the result of (i) that condensation reactions occurs between hydroxyl groups of the zeolite and Fe(OH) 3 formed from the Fe salts present with the zeolite, thus forming a chemical bond between the Fe and the zeolite including an oxygen bridge, wherein at least one of the remaining -OH groups of Fe may further react through condensation reaction with other Fe(OH) 3 or AI(OH) 3 or Si(OH) 3 wherein the product may further react through condensation reactions with hydroxyl groups of oxyhydroxides or Fe(OH) 3 or AI(OH) 3 or Si(OH) 3 thus forming the composition according to the invention.
  • Oxyhydroxides not bound to the zeolite may be formed by condensation reactions between Fe(OH) 3 , and/or AI(OH) 3 and/or Si(OH) 3 and or oxyhydroxides.
  • Particles or granules, such as sieved fractions, of the composition may be applied as a packing for an adsorber column.
  • particles of the composition according to the invention may be used as packing material for columns.
  • the adsorbent and the carrier may be linked by an oxygen bridge, or a -O- group.
  • the adsorbent and the carrier may be chemically bonded by a condensation reaction involving an -OH group of the zeolite.
  • the adsorbent and the zeolite may be linked by at least one -Si-O-M- group, wherein M is Fe, Al or Si, preferably Fe or Al, wherein M is part of the adsorbent.
  • the zeolite may be natural zeolite. It may be preferred that said natural zeolite is selected from the group comprising mordenite or clinoptilolite. Said mordenite or clinoptilolite may contain rhyolite tuffs having at least 30% by weight or preferably more than 70% by weight of zeolite. Zeolite according to the present invention may be obtained according to the following example:
  • Natural resourses of zeolite such as zeolite rock is treated by crushing followed by sieving and collection of desired size fraction(s), and removal of the clay mineral components from the fraction(s) from the sieving by washing.
  • Clay minerals washed out from the ground zeolite could otherwise contaminate the water feed to be treated by the composition according to the invention for a long time.
  • the zeolite is converted to its Na form during the washing; 0.5-2 molar NaCI solution is used for the washing in such an amount that the sodium content of the solution exceed the ion-exchange capacity of the washed zeolite.
  • the ion exchange and washing procedure may be carried out by suspending the zeolite in the NaCI solution followed by decanting the supernatant. Suspension-decantation steps are repeated with clean water until the supernatant becomes clear.
  • composition according to the invention may be prepared according to the following example:
  • zeolite particles are used, for example as prepared according to example 1 , which zeolite particles are free of clay minerals and are smaller than 5 mm, preferably smaller than 1 .41 mm or, most advantageously, having sizes between 0,5 and 1 ,41 mm.
  • the volume of the pores below 10 ⁇ radius is between 0.3-0.7 cm 3 /g, preferably higher than 0.5 cm 3 /g, for example 0.5-0.7 cm 3 /g.
  • the preparation of the composition according to the invention may include: (i) preparation of an iron or iron and aluminum salt solution, preferably chloride or sulphate salts of the metals, (ii) preparation of a sodium hydroxide or; water glass (Na 2 SiOs) and sodium hydroxide; or Si0 2 and sodium hydroxide containing, or a sodium hydroxide solution; (iii) mixing of the zeolite with the iron-containing or the iron and aluminum-containing solution, such that a suspension or slurry is obtained (iv) the iron containing solution and zeolite suspension is reacted with the sodium-hydroxide or water glass containing solution, during which reaction precipitate is formed (v) the precipitate is washed with for example water, thus removing chloride or sulphate until the suspension is essentially free from chloride and sulphate, (vi) the washed product is dried, (vii) obtaining suitable particle size fraction for the composition according to the invention.
  • an iron or iron and aluminum salt solution preferably chloride or
  • the step of providing said suspension with a basic solution may comprise providing an aqueous solution of an alkali hydroxide or a basic solution of silicate, Na2SiO2(OH)2/NaOH/H2O, for example by providing an aqueous solution of Si0 2 and NaOH or an aqueous solution of (Na2SiOs) and sodium hydroxide.
  • the suspension is an aqueous suspension, and preferably a suspension in water.
  • the iron salt according to the method of producing the composition according to the invention may be iron(l l l)chloride.
  • the providing of the iron salt may be providing an iron salt containing solution, for example by dissolving iron(l l l)chloride or iron(ll l)sulphate in aqueous solution, preferably water.
  • the aluminum salt according to the method of producing the composition according to the invention may be aluminum chloride or sulphate, it may be prefered that the aluminum salt is poly aluminum chloride, i.e a compound widespread in water cleaning technology.
  • the providing of the aluminum salt may be providing an aluminum salt containing solution, for example by dissolving aluminum(l l l)chloride or aluminum(l l l)sulphate in aqueous solution, preferably water.
  • the concentration of iron or aluminum may be chosen such that the amount of iron or aluminum required for the reactions and production of the composition according to the invention is contained in a volume that is equal or smaller than the pore volume of the zeolite.
  • the iron content of the composition may be between 0.5 and 20% by weight.
  • the Fe/AI ratio in the composition comprising both iron and aluminum may be above 3.
  • Concentration of sodium hydroxide may be chosen such that the desired or required amount of sodium is contained in a volume that is equal or smaller than the pore volume of the zeolite.
  • the amount of sodium, expressed in moles, may be lower than six times, but higher than three times the molar amount of iron(l l l) salt and aluminum(l l l) salt on the support.
  • Preparation of the composition according to one embodiment of the invention wherein the adsorbent comprises an oxyhydroxide comprising Fe and Al and/or Si may be carried out by reacting metal salt deposited on the zeolite and a solution containing an equivalent amount of sodium hydroxide, i.e.
  • compositions are effient for the objective of the present invention.
  • Preparation of composition according to one embodiment of the invention wherein the adsorbent comprises an oxyhydroxide comprising Fe and Si or Fe, Al, and Si may be carried out by the reaction of Fe(l l l) salt or the Fe(l l l) and Al(l l l) salt by waterglass/sodium hydroxide solution (such as S1O2 dissolved in sodium hydroxide).
  • the composition of the SiO2/sodium hydroxide solution may be controlled in such a way that the amount of sodium in moles may be contained in a volume that is equal or smaller than the pore volume of the support.
  • the molar amount of sodium may be higher that three times and less than than six times the total molar amount of iron(l l l) and aluminum(l l l) deposited on the zeolite.
  • the Si content of the adsorbent may regulated by the concentration of the S1O2 solution.
  • Fe/Si ratio or Fe/(AI+Si) ratio may be between 1 and 3.
  • the carrier comprising zeolite may be impregnated with highly acidic iron(l l l) salt or iron(l l l) salt and Al(l l l) salt and reacted with a highly basic sodium hydroxide or waterglass solution under the formation of Fe(OH) 3 , AI(OH) 3 and Si(OH) which then reacts with hyd roxyl groups of the zeolite by condensation.
  • Slow feeding of the alkaline solution and/or cooling of the reactor may be beneficial in order to avoid the increase of the reactor temperature due to the exotherm hydrolysis of the salt with the base.
  • the reactor temperature may thus be kept at or below 50°C. During the reactions a precipitate is formed and NaCI appears as reaction product.
  • the next step of the procedure may be to wash zeolite particles and the precipitate free from chloride. Washing may be carried out to obtain clear NaCI solution and to recover all the solids. The washing may be carried out by known methods, such as by means of filter centrifuge or multistep batch method, applying filter press.
  • the solid product comprising the composition according to the invention, may be shaped by known methods such as extrusion or pelletization and dried below 50°C, preferably at ambient temperature. It may be preferred with drying at temperatures lower than 50°C, followed by grinding and separating particles larger than 0.5 mm, suitable for use in adsorber column, by dry sieving or preferably wet sieving. Wet sieving may be followed by a repeated drying procedure, at temperatures below 50°C, preferably at ambient temperature.
  • Removal of arsenic from water may be carried out by adding the composition according to the invention to water and allowing the composition to adsorb arsenic followed by separation of the composition and the treated water.
  • Granular compositions may be separated from water by, for example, fast filtration and/or decantation. It may be preferred that the adsorbent is added to the water in an amount that following the attainment of the adsorption equilibrium the arsenic concentration of the water is below 10 ppb.
  • Removal of arsenic from water may also be carried out by applying the composition according to the present invention in an adsorber column. The water is fed through the column at a feed between 5 and 20 bed volume (BV)/hour, preferably 8-12 BV/hour, most preferably 10 BV/h.
  • the dynamic water cleaning capacity obtained with the compositions according to the invention for water containing 50-20 ppb arsenic reaches 100 000-300 000 bed volume until the breakthrough of the 10 ppb limit concentration.
  • the inventors of the present invention have unexpectedly realised that the high equilibrium adsorption capacity may be due to the formation of amorphous oxyhydroxides with high surface area and high iron content when compositions according to the present invention is prepared in accordence with the present invention.
  • Furhter the use of zeolite as carrier according to the invention results in efficient compositions. Mechanical and hydrodynamic properties of the adsorbent are similar to that of zeolite filters.
  • the inventors of the present invention have unexpectedly realised that the efficient composition of the present invention and its favorable dynamical adsorption properties may be due to hydrated Fe 3+ cations incorporated into the ion- exchange positions in the zeolite, the formation of active component with high iron content in the pores of the zeolite, the surface structure of the zeolite particle, and the amorphous oxyhydroxide particles with high specific surface and high iron content.
  • the adsorber column containing the composition according to the invention may be applied similarly as the filters commonly used in the drinking water technology be applied or may be appl ied as an add itional un it to the conventional water cleaning technology to remove residual arsenic.
  • the composition according to the invention may selectively adsorb other contaminants than arsenic, such as ammonium, heavy metals and colored metals thus further improving the quality of potable water.
  • composition according to the present invention may be produced from inexpensive materials, such as ground zeolite and other chemical components widely used in water treatment technologies. Regeneration of the inexpensive adsorbent is not necessary.
  • composition according to the invention includes that the dissolution of arsenic from compositions used for removal of arsenic from water is negligible, thus the arsenic containing adsorbent may be treated like an inert, non-toxic, inorganic waste.
  • Example 1 Preparation of Na-mordenite and Na-clinoptilolite.
  • Ground rhyolite tuff containing clinoptilolite or mordenite, originating from the Tokaj mountains, Hungary, are applied. By X-ray diffraction phase analysis it was found that the samples contain 60% by weight of clinoptilolite or 75% by weight of mordenite. Other components of the tuff are orthoclase, quartz and stilbite. 0.63-2.0 mm particle size fractions of the ground rhyolite tuff is treated with 1 M NaCI solution. 1 kg of ground rock is stirred with 10 L of the solution for 2 hours. Clay mineral components of the suspension are removed by decantation. The remaining solid material is suspended again in 5 L of water.
  • Na-clinoptilolite or Na-mordenite depending on the structure of the dominant zeolite mineral component.
  • the sodium content of Na-clinoptilolite and Na-mordenite is 1 .1 and 1 .3 meq/g, respectively.
  • Specific surface area of Na-mordenite is 137 m 2 /g and that of Na-clinoptilolite is 38 m 2 /g.
  • the pore volume of the pores smaller than 10 ⁇ is about 0.5 cm 3 /g.
  • Comparative example 2 Preparation of hvdrated iron(lll) oxide/mordenite adsorbent.
  • 0.25 L of 4 M FeCb solution is added by spraying in 5 minutes to 1 kg of Na- mordenite, obtained according to Example 1 , under constant stirring.
  • the mixture of 0.28 L 10 M NaOH solution and 76 g waterglass (the applied waterglass is a mixture of 26% by weight of S1O2 and sodium-hydroxide) is also added in 5 minutes under constant stirring.
  • the Fe/Si ratio of the mixture is 3.
  • the obtained gel was rinsed on evacuated filter funnel (P16 ISO 4793) with 10 L of water in 1 L portions and then dried at ambient or at low temperature below 50°C, spread in a thin layer. Fine particles are washed out by decantation with 10 x 1 L water and the material is dried in the same way as with the sample of Example 2. 70-80% of the loaded iron remains on the surface or among the particles of zeolite corresponding to an iron content of 3-4% by weight.
  • Example 4 Preparation of composition comprising oxyhydroxide comprising Fe and Si and carrier comprising clinoptilolite
  • iron-containing oxyhydroxide is formed from the gel. Particles, bigger than 0.5 mm are removed by wet sieving and the material is dried in the same fashion as with the samples of Examples 2 and 3. After washing 70-80% of the loaded iron remain on the surface or in the form of dark brown grains, among the particles of zeolite. Iron content of the preparation is 17 % by weight.
  • Example 5 Preparation of composition comprising oxyhydroxide comprising Fe and Al and carrier comprising clinoptilolite
  • a mixture of 1 L of 4 M FeCb solution and 0.28 L of 10% by weight aluminum- containing poly aluminum chloride (PAC) is sprayed in 5 minutes on 1 kg of Na-clinoptilolite under constant stirring. Finishing the loading of FeCb +PAC mixture, under constant stirring 1 .33 L of 10 M NaOH solution is added to the solid material in 5 minutes.
  • the Fe/AI ratio of the mixture is 3.
  • Reaction mixture is cooled or the feed is controlled to avoid the raise of reaction mixture temperature over 50°C.
  • the obtained gel is washed salt free on porous glass filter with 10 L water in 1 L portions then dried at room temperature or at temperatures below 50°C, preferably spread in a thin layer. During drying iron-containing oxyhydroxide is formed from the gel. Particles, bigger than 0.5 mm are removed by wet sieving and the material is dried in the same way as with the preceding Examples. Iron content of the preparation is 15% by weight.
  • Example 6 Preparation of composition comprising oxyhydroxide comprising Fe, Al and Si and carrier comprising mordenite
  • a mixture of 1 L of 2 M Fe(SO 4 ) 3 solution and 0.14 L of 1 0% by weight of aluminum-containing AI(SO 4 )3 solution is sprayed in 5 minutes on 1 kg of Na- mordenite under constant stirring .
  • Finish ing the loading of Fe 2 (SO 4 )3 + AI 2 (SO 4 )3 mixture, under constant stirring a mixture of 1 ,23 L of 10 M NaOH solution and 153 g of 26% by weight of SiO 2 -containing waterglass is added to the solid material in about 5 minutes. Reaction mixture is cooled or the feed is controlled to avoid the raise of reaction mixture temperature over 50°C.
  • the obtained gel is washed salt free on porous glass filter with 10 L water in 1 L portions then dried at room temperature or at temperatures below 50 °C, preferably spread in a thin layer.
  • iron-containing oxyhydroxide is formed from the gel. Particles, bigger than 0.5 mm are removed by wet sieving and the material is dried as in preceding Examples. Iron content of the preparation is 15 wt. %.
  • Arsenic contain ing test solutions are prepared by the d ilution of AS2O5 analytical standard solution. Tap water is used for the dilution . 50 mg of composition according to the invention was contacted with 60 cm 3 of arsenic containing solution. Initial As(V) concentration of the solution was 1 , 3 or 5 ppm. Equilibrium As concentration was measured and the amount of adsorbed As was calculated by the change of concentration. It was found that the amount of adsorbed As in the exam ined concentration range is proportional to the As concentration of the solution. The compositions are characterized by a proportionality coefficient, the so called Henry constant, as seen in Table 1 . The As content of the solutions was determined by graphite furnace atomic adsorption spectroscopy (GF-AAS). Example 8 - Dynamic adsorption capacity
  • a packed column was prepared by loading 10 cm long filling of the composition according to the invention in a glass tube with 12 mm diameter.
  • the As(V)-containing water was fed on the vertical packed column at the bottom with 100 cm 3 /h speed (10 BV/h).
  • Initial As concentration of the water input was 200 or 2000 ppb.
  • Arsenic content of the outlet water was monitored by frequent sampling and GF-AAS analysis, taking the breakthrough curves characteristic for the composition. The breakthrough was considered to occur when the arsenic concentration of outlet water reached 10 ppb. Typical breakthrough curves are shown in Fig. 1 .
  • Dynamic adsorption capacity is depending in small extent on the As concentration of the input solution, it is higher at lower concentration and lower at more concentrated solutions.
  • water cleaning capacity of an adsorber column, in BVs is at least as many times higher than that determined in the laboratory-scale experiments as many times the As concentration of the contaminated water is lower that of the water applied in the experiment.
  • an advantageous compositions of the present invention was applied to remove the residual arsenic content of the cleaned drinking water by the flow-through adsorber method.
  • the typical arsenic content of the water, pretreated by the commercial water cleaning technology was ⁇ 80 ppb.
  • the water purification was carried out in the technological steps of oxidation (10 L CI2 gas/m 3 water feed), coagulation/flocculation (2-5 mg iron salt/L water and lime milk feed) and filtering (fast filtering through sand bed under pressure).
  • the residual arsenic content of the cleaned water was 15-18 ppb, the pH was between 5 and 7 and PO 4 -P contamination (phosphate contamination expressed in phosphorous) was below 1 ppb.
  • a 2000 mm high stainless steel column with 254 mm inner diameter was filled with 100 L (ca. 85 kg) of Fe-Si-oxyhydroxide/zeolite composition prepared by the method described in Example 4.
  • a flow of cleaned water with 1 m 3 /h speed was fed at the bottom of the column.
  • the arsenic concentration of the outlet water at the top of the column was monitored by sampling and analyzing the samples by GF-AAS method. Over half year operation the arsenic concentration of outlet water d id not exceed the 1 0 ppb l imit. Laboratory experiments predict 2.5 year operation until breakthrough occurs.

Abstract

The present invention relates to a composition for removal of arsenic from water,the composition comprising an adsorbent and a carrier, characterized by the adsorbent comprising an oxyhydroxide comprising Fe, and Al and/or Si, and the carrier comprising zeolite, wherein the adsorbent being chemically bonded to the zeolite; a method for producing a composition for removal of arsenic from water; and a method for treatment of water containing arsenic.

Description

COMPOSITION FOR REMOVAL OF ARSENIC TECHNICAL FIELD
The present invention relates to a composition for removal of arsenic from water, a method for producing a composition for removal of arsenic from water, and a method for removal of arsenic from water.
TECHNICAL BACKGROUND
Arsenic is a highly toxic element, having frequent occurrence in nature. Numerous arsenic-containing minerals are known, and most of them are arsenides, arsenates, arsenites and sulfides. Arsenic content of ground and surface water can mostly be related to soil pollution from agriculture and industry. Water from bedrock wells can be contaminated by arsenic, dissolved from pyrogenic and sedimentary rocks. Ingested arsenic can cause lung, kidney, liver, skin, or bladder cancer; cardiovascular diseases; and neurological damage. Because of the toxicity of arsenic the Hungarian Government (201/2001 . (X. 25.) Gov. Legislation) in accordance with other national (e.g. USEPA) and international associations (WHO, EC) have regulated the maximum allowable concentration of arsenic in drinking water (MCL= maximum concentration limit) to 10 ppb (10 μ9/Ι). Thus, the arsenic content of water used for human consumption must be reduced below 1 0 ppb.
In nature, arsenic is present in organic and inorganic compounds. In natural waters the dominant forms of arsenic are the inorganic arsenite anion, containing arsenic in As(lll) form; or arsenate anion, containing arsenic in As(V) form. Oxidative environments favors the formation of arsenate, while reductive environments favours the arsenite in anionic form. The charge of the anion depends on pH, but cannot exceed three. Currently applied technologies for treatment of potable or waste water connect arsenic removal with iron and manganese removal. Iron and manganese pollutants are chemically oxidized and the resulting precipitate is filtered. The amount and surface area of iron-containing precipitates, active as arsenic adsorbing flocculants, can be increased by further addition of iron salts. By the hydrolysis of iron salt arsenic adsorbing iron hydroxides are formed. Precipitation and adsorption can be enhanced by addition of lime milk. Arsenites may be oxidized to better adsorbing arsenates by addition of manganese salts. Arsenic free water can be produced by the filtration removal of arsenic containing precipitates. However, complete removal of arsenic-containing colloidal particles, such as precipitates, is difficult. Filtration is usually performed on packed columns filled with sand or by membrane separation. Although oxidation/coagulation-flocculation/filtration may decrease the arsenic content of water, arsenic concentration below 10 ppb can generally not be achieved. Thus, there is a need for more efficient techniques concerning removal of arsenic from water.
Other removal technologies without filtration of precipitates are also known. One method for the decrease of arsenic concentration below 10 ppb is ion- exchange with synthetic ion-exchange resins, reverse osmosis or electrodialysis. These procedures are not widely applied in water treatment because they are expensive, and because of the formation of regenerant and retentate solutions with high concentration of arsenic requiring treatment as toxic waste water.
For the reduction of arsenic concentration below the permissible limit (<10 ppb) adsoption has also been applied. Adsorbents for arsenic removal are metallic iron, activated alumina, activated carbon, red mud, coconut shell, rice-bran and zeolites. However, the arsen ic adsorption capacity and selectivity of the above mentioned materials are too low. Thus there is a need for more efficient adsorbents for arsenic removal from water.
Iron(lll) oxides have higher adsorption capacities than the above mentioned adsorbents. The documents DE 4320003, US 6 809 062 and US 6 849 187 relates to production of grained or granulated iron(lll) oxides, for arsenic removal. Other existing adsorbents include amorphous or partly crystalline, hydrated iron(lll) oxide (FeOOH) or goethite (a-FeOOH) available under different trademarks such as AdsorpAs, Bayoxide E33, es GEH 33. Disadvantages with iron(lll) oxides for removal of arsenic is that the used adsorbent columns have to be exchanged frequently and the fragmentation of the adsorbent during the water treatment process. The patents US 7 291578 and US 7407 587 discloses preparation of hydrated metal oxides, among others iron(lll) oxide micro-sized particles and their immobilization on anion exchanger polymer resin for arsenic removal. However, the dynamic As adsorption capacity of the adsorbent is low and uptake of arsenic oxyanions is slow and the adsorbent needs to be regenerated and reutilized. Treatment and deposition of the highly arsenic and therefore toxic regenerate solution is difficult.
The US patent with number US 7 314 569 discloses adsorbents of iron oxyhydroxide microcrystals, such as akaganeite (β-FeOOH) bound to a zeolite surface. During the preparation of the adsorbent iron compounds not bound to the surface and iron-containing microparticles have to be removed in order to make the adsorbent suitable for water cleaning in an adsorber column. Further, the arsenic removal capacity of the adsorbents are too low, because the capacity is limited by the amount of active iron bound to the zeolite.
The use of zeolites, mainly natural zeolites is widespread in water cleaning as ion-exchanger or filtration material. Zeolites are ion-exchanged by iron-salts (US 6 042 731 , US 747631 1 ), iron-hydroxides are precipitated on the zeolite surface (US 6 790 363; C.-S. Jeon et. al.: Adsorption characteristics of As(V) on iron-coated zeolite. J. Hazard. Mater. 163 (2009) 804-808.), or iron oxyhydroxide microcrystals, like akaganeite (β-FeOOH) are bound to the zeolite surface (US 7 314 569). During the preparation of the adsorbent iron compounds not bound to the surface and iron-containing microparticles have to be removed in order to make the adsorbent suitable for water cleaning in an adsorber col umn . In practice the arsen ic removal capacity of the adsorbents are too low, because the capacity is limited by the amount of active iron bound to the zeolite. SUMMARY OF THE INVENTION
As used herein, Al is synonumos with aluminum. Si is synonumos with silicon. Fe is synonumos with iron.
One objective of the present invention is to provide an efficient composition for removal of arsenic from water without disadvantages associated with known techniques, as well as a method for producing such compositions and a method for removal of arsenic from water using such compositions.
According to a first aspect of the invention, the objective is realised by means of a composition for removal of arsenic from water, the composition
comprising an adsorbent and a carrier, characterized by the adsorbent comprising an oxyhydroxide comprising Fe, and Al and/or Si, and
the carrier comprising zeolite, wherein the adsorbent being chemically bonded to the zeolite.
Arsenic is intended to comprise any compound containing arsenic suitable for removal from water by the composition according to the invention. Arsenic may be selected from the group comprising elemental arsenic, arsenic present in organic compounds, arsenic present in inorganic compounds, inorganic arsenite anion containing arsenic in As(lll) form, arsenate anion containing arsenic in As(V) form, and mixtures thereof. An adsorbent comprising oxyhydroxides is efficient for interaction with arsenic containing compounds. The oxyhydroxide comprising Fe and Al and/or Si results in efficient interaction with arsenic containing compounds. Further, high equilibrium and dynamic arsenic adsorption capacity may be obtained with such a composition according to the invention.
The oxyhydroxide comprising Fe and Al and/or Si is a mixed oxyhydroxide with resulting efficient removal of arsenic from water when used for such purpose. The adsorbent being chemically bonded to the zeolite results in a strong link between the adsorbent and the carrier. The composition comprising an adsorbent and a carrier results in a mechanically stable composition. Further, a particulate composition may be obtained. Yet further, efficient handling and use of the composition is allowed, for example by packing the composition in a column. Such a composition may be efficient for removal of arsenic from water. Such particulate compositions may efficiently be removed from water after treatment of water by removal of arsenic from the water, for example by filtration or sedimentation of the composition from the treated water. Such compositions according to the invention may be suitable for the economical production of drinking water containing arsenic lower than 10 ppb
concentration. Zeolite may provide for an inexpensive adsorbent material which may be efficiently disposed, for example as non-hazardous landfill. The oxyhydroxide may be a polyoxyhydroxide. Thus, adsorbents with high molecular weight may be obtained and used in accordance with the invention.
Said Fe, and Al and/or Si may be linked by -O- bridges, and the oxyhydroxide may comprise terminal OH-groups. Thus the polyoxyhydroxide may be a compound consisting of the elements Fe and Al and/or Si, wherein each element is linked to one, two or three elements by an oxygen bridge. Each element may bind 0, 1 , or 2 hydroxyl groups, such that each element binds a total of three groups including hydroxyl groups and other elements via oxygen bridge.
The molar ratio of Fe to Si; Fe to Al; or Fe to Si and Al; may be above 1 .
Thus, the adsorbent and/or the oxyhydroxide may contain more Fe than the total amount of Al and Si, on a molar basis. Such a ratio results in efficient adsorbents and removal of arsenic. It may be preferred that the molar ratio of Fe to Si; Fe to Al; or Fe to Si and Al is above 3. Thus, an even more efficient adsorbent may be obtained and even more efficient removal of arsenic may be realized.
The composition may be in the form of granules smaller than 5 mm. Such sizes of granules of the composition may result in efficient removal of arsenic and desirable properties for removal of arsenic when the composition is packed in columns. Further, such sizes may efficiently be obtained by sieving. It may be preferred that the composition is in the form of granules smaller than 1 .41 mm, and most preferably between 0.5 and 1 .41 mm. Such preferred sizes may result in highly efficient removal of arsenic from water.
According to a second aspect of the invention, the objective is realized by a method for producing a composition for removal of arsenic from water, comprising the steps of: providing iron salt and optionally aluminum salt;
providing particulate zeolite; obtaining a suspension of said iron salt and optionally aluminum salt and said particulate zeolite; providing said
suspension with a basic solution; optional mixing of the suspension with the basic solution; allowing chemical reaction to take place, producing a composition comprising oxyhydroxide, which oxyhydroxide comprises Fe, and Al and/or Si, chemically bonded to zeolite; collecting said composition.
Preferred basic solutions are basic solutions of silicate and/or alkali hydroxide solutions, e.g. an sodium hydroxide solution.
Iron salt and optionally aluminum salt may be efficient starting materials for producing of the composition. Obtaining a suspension of said iron salt and optionally aluminum salt and said particulate zeolite may be an efficient means for impregnating the zeolite with iron, and thus further to obtain efficient reaction between the iron and the zeolite.
Providing said suspension with a basic solution may result in that Fe(lll)(OH)3 is formed from the iron, and if the basic solution is a basic solution of silicate to provide Si-ions and/or Si(OH)3. Mixing of said suspension may make the chemical reaction to be efficient. Allowing chemical reaction to take place may result in chemical bonds are being formed such that iron is linked to zeolite via an oxygen bridge. Further it may allow condensation reactions to take place such that oxyhydroxides are formed comprising Fe, and Al and/or Si. Further, the oxyhydroxide may via condensation reaction be bonded to the zeolite. Thus, the chemical reaction thus results in the composition according to the invention comprising adsorbent comprising oxyhydroxide chemically bonded to the carrier comprising zeolite. Collecting said composition allows for further use of the composition. The step of allowing chemical reaction may be followed by removal of alkali salts by washing with water. Thus, the concentration of alkali salts in solution with the composition is reduced. Said iron salt may be iron(lll)chloride and said aluminium salt may be aluminium(lll)chloride. Such salts may be efficient for producing the composition according to the invention.
The basic solution may be an alkali hydroxide solution, preferably a sodium hydroxide solution.
The basic solution of silicate may be an aqueous solution of Na2SiO2(OH)2 and alkali hydroxide, preferably NaOH, or S1O2 and alkali hydroxide, preferably NaOH. Such a solution may be effient for the invention.
The chemical reaction may involve forming an oxygen bridge between the oxyhydroxide and the zeolite. Thus, efficient and suitable bonds may be obtained between the adsorbent and the carrier. The chemical reaction may involves hydroxyl group of the zeolite.
Thus, efficient chemical reaction and condensation reactions may take place.
According to a third aspect of the invention the objective is achieved by a product obtainable by said method for removal of arsenic from water. Such a product is efficient for removal of arsenic from water.
According to a fourth aspect of the invention, the objective is achieved by a method for treatment of water containing arsenic, wherein said composition is contacted with the water and is allowed to adsorb arsenic from the water. Thus arsenic dissolved or in other ways present in the water may be removed from the water by being adsorbed to the composition.
Said method for treatment of water may further comprise the step of separating the composition with adsorbed arsenic and the treated water. Thus, arsenic may be removed from the vicinity of the water. Further the arsenic may be deposited away from the water. The treated water from said method of treatment of water may contain less than 10 ppb of arsenic. Thus very low concentration of arsenic in the treated water may be obtained. The water in the method for treatment of water according to the invention may be ground water, river water, industrial waste water, civic waste water, potable water and/or surface water.
The above discussions concerning the composition may also be applied to the methods or the product obtainable by the methods and vice versa, references to these discussions, where applicable, are hereby made.
BRIEF DESCRIPTION OF DRAWINGS Figure 1 illustrates arsenic breakthrough curves of adsorbents.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described in more detail and preferred embodiments will be described. The descriptions is intended for illustrative and describing purposes only and the descriptions should not, in any way, be interpreted as being limiting the scope of the invention. The figures are schematic and all illustrated details may not be necessary for the invention, and all details necessary for the invention may not be illustrated.
One embodiment of the present invention, involves condensation reaction occuring between hydroxyl groups of the zeolite and hydroxyl groups of the Fe-hydroxide. The Fe-hydroxide is co-precipitated in the presence of the zeolite with Si-hydroxide and/or Al-hydroxide. In the reactions mixed oxyhydroxide polymers comprising Fe and Al and/or Si, chemically bound to zeolite support, and mixed oxyhydroxides comprising Fe and Al and/or Si particles not being bound to zeolite are formed. The formation of the oxyhydroxides chemically bound to the zeolite is the result of (i) that condensation reactions occurs between hydroxyl groups of the zeolite and Fe(OH)3 formed from the Fe salts present with the zeolite, thus forming a chemical bond between the Fe and the zeolite including an oxygen bridge, wherein at least one of the remaining -OH groups of Fe may further react through condensation reaction with other Fe(OH)3 or AI(OH)3 or Si(OH)3 wherein the product may further react through condensation reactions with hydroxyl groups of oxyhydroxides or Fe(OH)3 or AI(OH)3 or Si(OH)3 thus forming the composition according to the invention. Oxyhydroxides not bound to the zeolite may be formed by condensation reactions between Fe(OH)3, and/or AI(OH)3 and/or Si(OH)3 and or oxyhydroxides. Particles or granules, such as sieved fractions, of the composition may be applied as a packing for an adsorber column. Thus, according to one embodiment of the invention particles of the composition according to the invention may be used as packing material for columns. The compositon according to the invention and the composition applied as packingmaterial for columns, such as adsorption coumns, yields high equilibrium and dynamic arsenic adsorption capacity. The adsorbent and the carrier may be linked by an oxygen bridge, or a -O- group.
The adsorbent and the carrier may be chemically bonded by a condensation reaction involving an -OH group of the zeolite.
According to one embodiment of the invention, the adsorbent and the zeolite may be linked by at least one -Si-O-M- group, wherein M is Fe, Al or Si, preferably Fe or Al, wherein M is part of the adsorbent. According to the invention, the zeolite may be natural zeolite. It may be preferred that said natural zeolite is selected from the group comprising mordenite or clinoptilolite. Said mordenite or clinoptilolite may contain rhyolite tuffs having at least 30% by weight or preferably more than 70% by weight of zeolite. Zeolite according to the present invention may be obtained according to the following example:
Natural resourses of zeolite, such as zeolite rock is treated by crushing followed by sieving and collection of desired size fraction(s), and removal of the clay mineral components from the fraction(s) from the sieving by washing. Clay minerals washed out from the ground zeolite could otherwise contaminate the water feed to be treated by the composition according to the invention for a long time. The zeolite is converted to its Na form during the washing; 0.5-2 molar NaCI solution is used for the washing in such an amount that the sodium content of the solution exceed the ion-exchange capacity of the washed zeolite. The ion exchange and washing procedure may be carried out by suspending the zeolite in the NaCI solution followed by decanting the supernatant. Suspension-decantation steps are repeated with clean water until the supernatant becomes clear.
The composition according to the invention may be prepared according to the following example:
For the preparation of the adsorbent, zeolite particles are used, for example as prepared according to example 1 , which zeolite particles are free of clay minerals and are smaller than 5 mm, preferably smaller than 1 .41 mm or, most advantageously, having sizes between 0,5 and 1 ,41 mm. The volume of the pores below 10 μιτι radius is between 0.3-0.7 cm3/g, preferably higher than 0.5 cm3/g, for example 0.5-0.7 cm3/g.
The preparation of the composition according to the invention may include: (i) preparation of an iron or iron and aluminum salt solution, preferably chloride or sulphate salts of the metals, (ii) preparation of a sodium hydroxide or; water glass (Na2SiOs) and sodium hydroxide; or Si02 and sodium hydroxide containing, or a sodium hydroxide solution; (iii) mixing of the zeolite with the iron-containing or the iron and aluminum-containing solution, such that a suspension or slurry is obtained (iv) the iron containing solution and zeolite suspension is reacted with the sodium-hydroxide or water glass containing solution, during which reaction precipitate is formed (v) the precipitate is washed with for example water, thus removing chloride or sulphate until the suspension is essentially free from chloride and sulphate, (vi) the washed product is dried, (vii) obtaining suitable particle size fraction for the composition according to the invention.
Thus, the step of providing said suspension with a basic solution, according to the method for producing a composition for removal of arsenic from water, may comprise providing an aqueous solution of an alkali hydroxide or a basic solution of silicate, Na2SiO2(OH)2/NaOH/H2O, for example by providing an aqueous solution of Si02 and NaOH or an aqueous solution of (Na2SiOs) and sodium hydroxide.
According to one embodiment of the method for producing a composition for removal of arsenic from water, the suspension is an aqueous suspension, and preferably a suspension in water.
The iron salt according to the method of producing the composition according to the invention may be iron(l l l)chloride. The providing of the iron salt may be providing an iron salt containing solution, for example by dissolving iron(l l l)chloride or iron(ll l)sulphate in aqueous solution, preferably water.
The aluminum salt according to the method of producing the composition according to the invention may be aluminum chloride or sulphate, it may be prefered that the aluminum salt is poly aluminum chloride, i.e a compound widespread in water cleaning technology. The providing of the aluminum salt may be providing an aluminum salt containing solution, for example by dissolving aluminum(l l l)chloride or aluminum(l l l)sulphate in aqueous solution, preferably water.
The concentration of iron or aluminum may be chosen such that the amount of iron or aluminum required for the reactions and production of the composition according to the invention is contained in a volume that is equal or smaller than the pore volume of the zeolite. The iron content of the composition may be between 0.5 and 20% by weight.. The Fe/AI ratio in the composition comprising both iron and aluminum may be above 3.
Concentration of sodium hydroxide may be chosen such that the desired or required amount of sodium is contained in a volume that is equal or smaller than the pore volume of the zeolite. The amount of sodium, expressed in moles, may be lower than six times, but higher than three times the molar amount of iron(l l l) salt and aluminum(l l l) salt on the support. Preparation of the composition according to one embodiment of the invention wherein the adsorbent comprises an oxyhydroxide comprising Fe and Al and/or Si, may be carried out by reacting metal salt deposited on the zeolite and a solution containing an equivalent amount of sodium hydroxide, i.e. three times the total molar amount of Fe and Al or more, but not exceeding six times the molar amount of Fe amd Al. Such compositions are effient for the objective of the present invention. Preparation of composition according to one embodiment of the invention wherein the adsorbent comprises an oxyhydroxide comprising Fe and Si or Fe, Al, and Si may be carried out by the reaction of Fe(l l l) salt or the Fe(l l l) and Al(l l l) salt by waterglass/sodium hydroxide solution (such as S1O2 dissolved in sodium hydroxide). The composition of the SiO2/sodium hydroxide solution may be controlled in such a way that the amount of sodium in moles may be contained in a volume that is equal or smaller than the pore volume of the support. In the solution the molar amount of sodium may be higher that three times and less than than six times the total molar amount of iron(l l l) and aluminum(l l l) deposited on the zeolite. The Si content of the adsorbent may regulated by the concentration of the S1O2 solution. Fe/Si ratio or Fe/(AI+Si) ratio may be between 1 and 3.
The carrier comprising zeolite may be impregnated with highly acidic iron(l l l) salt or iron(l l l) salt and Al(l l l) salt and reacted with a highly basic sodium hydroxide or waterglass solution under the formation of Fe(OH)3, AI(OH)3 and Si(OH) which then reacts with hyd roxyl groups of the zeolite by condensation. Slow feeding of the alkaline solution and/or cooling of the reactor may be beneficial in order to avoid the increase of the reactor temperature due to the exotherm hydrolysis of the salt with the base. The reactor temperature may thus be kept at or below 50°C. During the reactions a precipitate is formed and NaCI appears as reaction product. The next step of the procedure may be to wash zeolite particles and the precipitate free from chloride. Washing may be carried out to obtain clear NaCI solution and to recover all the solids. The washing may be carried out by known methods, such as by means of filter centrifuge or multistep batch method, applying filter press.
Following the washing, the solid product, comprising the composition according to the invention, may be shaped by known methods such as extrusion or pelletization and dried below 50°C, preferably at ambient temperature. It may be preferred with drying at temperatures lower than 50°C, followed by grinding and separating particles larger than 0.5 mm, suitable for use in adsorber column, by dry sieving or preferably wet sieving. Wet sieving may be followed by a repeated drying procedure, at temperatures below 50°C, preferably at ambient temperature.
The experiments showed that the arsenic adsorption selectivity of the composition according to the invention prepared by the methods according to the invention is unexpectedly high and that the arsenic adsorption capacity is unexpectedly higher as compraed with known adsorbents.
Removal of arsenic from water may be carried out by adding the composition according to the invention to water and allowing the composition to adsorb arsenic followed by separation of the composition and the treated water. Granular compositions may be separated from water by, for example, fast filtration and/or decantation. It may be preferred that the adsorbent is added to the water in an amount that following the attainment of the adsorption equilibrium the arsenic concentration of the water is below 10 ppb. Removal of arsenic from water may also be carried out by applying the composition according to the present invention in an adsorber column. The water is fed through the column at a feed between 5 and 20 bed volume (BV)/hour, preferably 8-12 BV/hour, most preferably 10 BV/h. The dynamic water cleaning capacity obtained with the compositions according to the invention for water containing 50-20 ppb arsenic reaches 100 000-300 000 bed volume until the breakthrough of the 10 ppb limit concentration.
The inventors of the present invention have unexpectedly realised that the high equilibrium adsorption capacity may be due to the formation of amorphous oxyhydroxides with high surface area and high iron content when compositions according to the present invention is prepared in accordence with the present invention.. Furhter, the use of zeolite as carrier according to the invention results in efficient compositions. Mechanical and hydrodynamic properties of the adsorbent are similar to that of zeolite filters. Further the inventors of the present invention have unexpectedly realised that the efficient composition of the present invention and its favorable dynamical adsorption properties may be due to hydrated Fe3+ cations incorporated into the ion- exchange positions in the zeolite, the formation of active component with high iron content in the pores of the zeolite, the surface structure of the zeolite particle, and the amorphous oxyhydroxide particles with high specific surface and high iron content.
The adsorber column containing the composition according to the invention may be applied similarly as the filters commonly used in the drinking water technology be applied or may be appl ied as an add itional un it to the conventional water cleaning technology to remove residual arsenic. In addition to the removal of arsenic, the composition according to the invention may selectively adsorb other contaminants than arsenic, such as ammonium, heavy metals and colored metals thus further improving the quality of potable water.
Further unexpected advantages with the composition according to the present invention include that the composition may be produced from inexpensive materials, such as ground zeolite and other chemical components widely used in water treatment technologies. Regeneration of the inexpensive adsorbent is not necessary.
Yet further unexpected advantages with the composition according to the invention includes that the dissolution of arsenic from compositions used for removal of arsenic from water is negligible, thus the arsenic containing adsorbent may be treated like an inert, non-toxic, inorganic waste.
EXAMPLES
The preparation of the composition according to the invention, the properties and characteristics of the composition, and the use of the composition for removal of arsenic from watern according to the present invention are illustrated by the following examples: Example 1 - Preparation of Na-mordenite and Na-clinoptilolite.
Ground rhyolite tuff, containing clinoptilolite or mordenite, originating from the Tokaj mountains, Hungary, are applied. By X-ray diffraction phase analysis it was found that the samples contain 60% by weight of clinoptilolite or 75% by weight of mordenite. Other components of the tuff are orthoclase, quartz and stilbite. 0.63-2.0 mm particle size fractions of the ground rhyolite tuff is treated with 1 M NaCI solution. 1 kg of ground rock is stirred with 10 L of the solution for 2 hours. Clay mineral components of the suspension are removed by decantation. The remaining solid material is suspended again in 5 L of water. The suspension is decanted once again, and the rest is washed salt free on a 0.25 mm sieve with 5 L of water repeated three times and dried at 120°C. Henceforth the grou nd rock is cal led Na-clinoptilolite or Na-mordenite, depending on the structure of the dominant zeolite mineral component. The sodium content of Na-clinoptilolite and Na-mordenite is 1 .1 and 1 .3 meq/g, respectively. Specific surface area of Na-mordenite is 137 m2/g and that of Na-clinoptilolite is 38 m2/g. The pore volume of the pores smaller than 10 μιτι is about 0.5 cm3/g.
Comparative example 2 - Preparation of hvdrated iron(lll) oxide/mordenite adsorbent.
0.5 L of 1 M FeCb solution is added by spraying for 5 minutes to 1 kg of Na- mordenite, obtained according to Example 1 , under constant stirring. 0.75 L of 2 M NaOH solution is added in 5 minutes under constant stirring. The suspension is stirred for 0.5 hour and allowed to stay for 24 hours. Then, the material is washed by decantation until colorless with 1 L portions of water. The solid rest is dried at room temperature or at low temperature below 50°C, spread in a thin layer. 20-22% of the loaded iron remains on the surface of the zeolite particles corresponding to an iron content of 0.6% by weight. Example 3 - Preparation of composition comprising oxyhvdroxide comprising Fe and Si and carrier comprising mordenite
0.25 L of 4 M FeCb solution is added by spraying in 5 minutes to 1 kg of Na- mordenite, obtained according to Example 1 , under constant stirring. The mixture of 0.28 L 10 M NaOH solution and 76 g waterglass (the applied waterglass is a mixture of 26% by weight of S1O2 and sodium-hydroxide) is also added in 5 minutes under constant stirring. The Fe/Si ratio of the mixture is 3. The obtained gel was rinsed on evacuated filter funnel (P16 ISO 4793) with 10 L of water in 1 L portions and then dried at ambient or at low temperature below 50°C, spread in a thin layer. Fine particles are washed out by decantation with 10 x 1 L water and the material is dried in the same way as with the sample of Example 2. 70-80% of the loaded iron remains on the surface or among the particles of zeolite corresponding to an iron content of 3-4% by weight.
Example 4 - Preparation of composition comprising oxyhydroxide comprising Fe and Si and carrier comprising clinoptilolite
By means of spraying 1 L of 4 M FeCb solution is added in 5 minutes to 1 kg of Na-clinoptilolite, obtained according to Example 1 , under constant stirring (preferably, by rotating a tilted container). Following the loading of FeCb solution, under constant stirring the mixture of 1 .12 L of 10 M NaOH solution and 306 g waterglass with a content of S1O2 of 26% by weight is added in 5 minutes. The Fe/Si ratio of the mixture is 3. The reaction mixture is cooled or the feed is controlled to avoid the raise of reaction mixture temperature over 50°C. The obtained gel is washed salt free on porous glass filter with 10 L water in 1 L portions then dried at room temperature or at temperatures below 50°C, preferably spread in a th in layer. During d rying iron-containing oxyhydroxide is formed from the gel. Particles, bigger than 0.5 mm are removed by wet sieving and the material is dried in the same fashion as with the samples of Examples 2 and 3. After washing 70-80% of the loaded iron remain on the surface or in the form of dark brown grains, among the particles of zeolite. Iron content of the preparation is 17 % by weight.
Example 5 - Preparation of composition comprising oxyhydroxide comprising Fe and Al and carrier comprising clinoptilolite
A mixture of 1 L of 4 M FeCb solution and 0.28 L of 10% by weight aluminum- containing poly aluminum chloride (PAC) is sprayed in 5 minutes on 1 kg of Na-clinoptilolite under constant stirring. Finishing the loading of FeCb +PAC mixture, under constant stirring 1 .33 L of 10 M NaOH solution is added to the solid material in 5 minutes. The Fe/AI ratio of the mixture is 3. Reaction mixture is cooled or the feed is controlled to avoid the raise of reaction mixture temperature over 50°C. The obtained gel is washed salt free on porous glass filter with 10 L water in 1 L portions then dried at room temperature or at temperatures below 50°C, preferably spread in a thin layer. During drying iron-containing oxyhydroxide is formed from the gel. Particles, bigger than 0.5 mm are removed by wet sieving and the material is dried in the same way as with the preceding Examples. Iron content of the preparation is 15% by weight.
Example 6 - Preparation of composition comprising oxyhydroxide comprising Fe, Al and Si and carrier comprising mordenite
A mixture of 1 L of 2 M Fe(SO4)3 solution and 0.14 L of 1 0% by weight of aluminum-containing AI(SO4)3 solution is sprayed in 5 minutes on 1 kg of Na- mordenite under constant stirring . Finish ing the loading of Fe2(SO4)3 + AI2(SO4)3 mixture, under constant stirring a mixture of 1 ,23 L of 10 M NaOH solution and 153 g of 26% by weight of SiO2-containing waterglass is added to the solid material in about 5 minutes. Reaction mixture is cooled or the feed is controlled to avoid the raise of reaction mixture temperature over 50°C. The obtained gel is washed salt free on porous glass filter with 10 L water in 1 L portions then dried at room temperature or at temperatures below 50 °C, preferably spread in a thin layer. During drying iron-containing oxyhydroxide is formed from the gel. Particles, bigger than 0.5 mm are removed by wet sieving and the material is dried as in preceding Examples. Iron content of the preparation is 15 wt. %.
Example 7 - Equilibrium adsorption capacity
Arsenic contain ing test solutions are prepared by the d ilution of AS2O5 analytical standard solution. Tap water is used for the dilution . 50 mg of composition according to the invention was contacted with 60 cm3 of arsenic containing solution. Initial As(V) concentration of the solution was 1 , 3 or 5 ppm. Equilibrium As concentration was measured and the amount of adsorbed As was calculated by the change of concentration. It was found that the amount of adsorbed As in the exam ined concentration range is proportional to the As concentration of the solution. The compositions are characterized by a proportionality coefficient, the so called Henry constant, as seen in Table 1 . The As content of the solutions was determined by graphite furnace atomic adsorption spectroscopy (GF-AAS). Example 8 - Dynamic adsorption capacity
A packed column was prepared by loading 10 cm long filling of the composition according to the invention in a glass tube with 12 mm diameter. The As(V)-containing water was fed on the vertical packed column at the bottom with 100 cm3/h speed (10 BV/h). Initial As concentration of the water input was 200 or 2000 ppb. Arsenic content of the outlet water was monitored by frequent sampling and GF-AAS analysis, taking the breakthrough curves characteristic for the composition. The breakthrough was considered to occur when the arsenic concentration of outlet water reached 10 ppb. Typical breakthrough curves are shown in Fig. 1 .
The amount of arsenic adsorbed until the breakthrough occurred was considered the dynamic adsorption capacity. Dynamic adsorption capacity is depending in small extent on the As concentration of the input solution, it is higher at lower concentration and lower at more concentrated solutions. In practice the water cleaning capacity of an adsorber column, in BVs, is at least as many times higher than that determined in the laboratory-scale experiments as many times the As concentration of the contaminated water is lower that of the water applied in the experiment.
Dynamical As adsorption and water clean ing capacity of the prepared compositions are shown in Table 1 .
Table 1 . Equilibriunn and dynamic arsenic adsorption characteristics of the compositions of Examples 1 -6.
Figure imgf000021_0001
a Henry constant K= Q (mg As/gComposition)/ceq.(mg As/dm3), where Q is the amount of adsorbed arsenic at ceq. equilibrium As concentration. b until the appearance of 1 0 ppb As concentration in outlet water. c Comparative example. d the value was estimated from the capacity measured at 2000 ppb As concentration. Example 9 - Arsenic removal from cleaned ground water by adsorption.
At a water supplier company an advantageous compositions of the present invention was applied to remove the residual arsenic content of the cleaned drinking water by the flow-through adsorber method. The typical arsenic content of the water, pretreated by the commercial water cleaning technology was <80 ppb. According to the commercial technology the water purification was carried out in the technological steps of oxidation (10 L CI2 gas/m3 water feed), coagulation/flocculation (2-5 mg iron salt/L water and lime milk feed) and filtering (fast filtering through sand bed under pressure). The residual arsenic content of the cleaned water was 15-18 ppb, the pH was between 5 and 7 and PO4-P contamination (phosphate contamination expressed in phosphorous) was below 1 ppb.
A 2000 mm high stainless steel column with 254 mm inner diameter was filled with 100 L (ca. 85 kg) of Fe-Si-oxyhydroxide/zeolite composition prepared by the method described in Example 4. A flow of cleaned water with 1 m3/h speed was fed at the bottom of the column. The arsenic concentration of the outlet water at the top of the column was monitored by sampling and analyzing the samples by GF-AAS method. Over half year operation the arsenic concentration of outlet water d id not exceed the 1 0 ppb l imit. Laboratory experiments predict 2.5 year operation until breakthrough occurs.

Claims

1 . Connposition for removal of arsenic from water, the composition comprising an adsorbent and a carrier, c h a r a c t e r i z e d b y
the adsorbent comprising an oxyhydroxide comprising Fe, and Al and/or Si, and
the carrier comprising zeolite,
wherein the adsorbent being chemically bonded to the zeolite.
2. The composition according to claim 1 wherein the oxyhydroxide is a polyoxyhydroxide.
3. The composition according to claim 1 or 2, wherein said Fe, and Al and/or Si are linked by -O- bridges, and wherein the oxyhydroxide comprises terminal OH-groups.
4. The composition according to anyone of the preceding claims wherein the molar ratio of Fe to Si; Fe to Al; or Fe to Si and Al; is above 1 , preferably above 3.
5. The composition according to anyone of the preceding claims, wherein the composition is in the form of granules smaller than 5 mm, preferably smaller than 1 .41 mm, and most preferably between 0.5 and 1 .41 mm.
6. Method for producing a composition for removal of arsenic from water, comprising the steps of:
- providing iron salt and optionally aluminum salt,
- providing particulate zeolite,
- obtaining a suspension of said iron salt and optionally aluminum salt and said particulate zeolite,
- providing said suspension with a basic solution,
- optional mixing of the suspension with the basic solution,
- allowing chemical reaction to take place, producing a composition comprising oxyhydroxide, which oxyhydroxide comprises Fe, and Al and/or
Si, chemically bonded to zeolite, - collecting said composition.
7. The method according to claim 6, wherein the step of allowing chemical reaction is followed by removal of alkali salts by washing with water.
8. The method according to claim 6 or 7, wherein said iron salt is iron(lll) chloride and said aluminium salt is aluminium(lll) chloride.
9. The method according to claims 6-8, wherein the basic solution is an alkali hydroxide solution.
10. The method according to claims 6-8, wherein the basic solution is a sodium hydroxide solution.
1 1 . The method according to claims 6-8, wherein the basic solution is a basic solution of silicate.
12. The method according to claim 1 1 , wherein the basic solution of silicate is an aqueous solution of Na2SiO2(OH)2 and alkali hydroxide, or S1O2 and alkali hydroxide.
13. The method according to claim 12, wherein the alkali hydroxide is NaOH,
14. Product obtainable by the method according to anyone of claims 6-13 for removal of arsenic from water.
15. Method for treatment of water containing arsenic, wherein a composition according to anyone of claims 1 -5 is contacted with the water and is allowed to adsorb arsenic from the water.
16. The method for treatment of water according to claim 15, further comprising the step of separating the composition with adsorbed arsenic and the treated water.
17. The method for treatment of water according to claim 15, wherein the composition is immobilised inside a column.
18. The method for treatment of water according to anyone of claims 15-17, wherein the treated water contains less than 10 ppb of arsenic.
19. The method for treatment of water according to anyone of claims 15-18, wherein the water is ground water, river water, industrial waste water, civic waste water, potable water and/or surface water.
PCT/SE2010/050864 2010-07-22 2010-07-22 Composition for removal of arsenic WO2012011856A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/SE2010/050864 WO2012011856A1 (en) 2010-07-22 2010-07-22 Composition for removal of arsenic

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/SE2010/050864 WO2012011856A1 (en) 2010-07-22 2010-07-22 Composition for removal of arsenic

Publications (1)

Publication Number Publication Date
WO2012011856A1 true WO2012011856A1 (en) 2012-01-26

Family

ID=45497073

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2010/050864 WO2012011856A1 (en) 2010-07-22 2010-07-22 Composition for removal of arsenic

Country Status (1)

Country Link
WO (1) WO2012011856A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111874953A (en) * 2020-08-07 2020-11-03 华北科技学院 Poly aluminum ferric chloride, preparation method thereof and flame retardant composition
CN116212625A (en) * 2023-05-09 2023-06-06 明硕环境科技集团股份有限公司 High-strength ferric hydroxide desulfurizing agent and preparation method thereof

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090264280A1 (en) * 2007-01-09 2009-10-22 Nikolay Aleksandrovich BADULIN Sorbent for removing heavy metal ions from water

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090264280A1 (en) * 2007-01-09 2009-10-22 Nikolay Aleksandrovich BADULIN Sorbent for removing heavy metal ions from water

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
HABUDA STANIC ET AL.: "Arsenite and arsenate sorption by hydrous ferric oxide/polymeric material", DESALINATION, vol. 229, no. 2208, pages 1 - 9 *
HYE JIN HONG ET AL.: "Preparation and Evaluation of Fe-Al Binary Oxide for Arsenic removal: Comparative study with Single Metal Oxides", SEPARATION SCIENCE AND TECHNOLOGY, vol. 45, 2010, pages 1975 - 1981 *
LE ZENG: "A method for preparing silica-containing iron(III) oxide adsorbents for arsenic removal", WATER RESEARCH, vol. 37, 2003, pages 4351 - 4358 *
MOHAN ET AL.: "Arsenic removal from water/wastewater using adsorbents - A critical review", JOURNAL OF HAZARDOUS MATERIALS, vol. 142, 2007, pages 1 - 53 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111874953A (en) * 2020-08-07 2020-11-03 华北科技学院 Poly aluminum ferric chloride, preparation method thereof and flame retardant composition
CN111874953B (en) * 2020-08-07 2022-06-24 华北科技学院 Poly aluminum ferric chloride, preparation method thereof and flame retardant composition
CN116212625A (en) * 2023-05-09 2023-06-06 明硕环境科技集团股份有限公司 High-strength ferric hydroxide desulfurizing agent and preparation method thereof
CN116212625B (en) * 2023-05-09 2023-09-05 明硕环境科技集团股份有限公司 High-strength ferric hydroxide desulfurizing agent and preparation method thereof

Similar Documents

Publication Publication Date Title
Taha et al. Multi-component adsorption of Pb (II), Cd (II), and Ni (II) onto Egyptian Na-activated bentonite; equilibrium, kinetics, thermodynamics, and application for seawater desalination
KR100951492B1 (en) Mixtures of Adsorber Materials
US8110526B2 (en) Arsenic absorbing composition and methods of use
Amer et al. ِAdsorption of lead, zinc and cadmium ions on polyphosphate-modified kaolinite clay
EP0561998B1 (en) The removal of heavy metals, especially lead, from aqueous systems containing competing ions utilizing amorphous tin and titanium silicates
Albayati et al. Adsorption of binary and multi heavy metals ions from aqueous solution by amine functionalized SBA-15 mesoporous adsorbent in a batch system
US6824690B1 (en) Zirconium-modified materials for selective adsorption and removal of aqueous arsenic
JP5482979B2 (en) Adsorbent
Irannajad et al. Removal of Co2+, Ni2+, and Pb2+ by manganese oxide-coated zeolite: equilibrium, thermodynamics, and kinetics studies
CA2598074A1 (en) Products and methods for removing substances from aqueous solution
WO2004052532A1 (en) Improved arsenic removal media
CN109476512B (en) Composition and method for removing arsenic and heavy metals from water
Bahabadi et al. Removal of Cd, Cu and Zn ions from aqueous solutions using natural and Fe modified sepiolite, zeolite and palygorskite clay minerals
Szala et al. Removal of chromium (VI) from aqueous solutions using zeolites modified with HDTMA and ODTMA surfactants
El Mouzdahir et al. Interaction of stevensite with Cd2+ and Pb2+ in aqueous dispersions
Shawabkeh et al. Cobalt and zinc removal from aqueous solution by chemically treated bentonite
Milićević et al. Removal of heavy metals from aqueous solution using natural and Fe (III) oxyhydroxide clinoptilolite
Almjadleh et al. Use of natural and modified Jordanian zeolitic tuff for removal of cadmium (II) from aqueous solutions
WO2012011856A1 (en) Composition for removal of arsenic
TWI672273B (en) Adsorption method
JP7177703B2 (en) Water purification device and water purification method using layered double hydroxide
Janashvili et al. Natural zeolite clinoptilolite as adsorbent for cleaning waters from arsenic ions
El-Nahas et al. A new and successful utilization of Egyptalum company solid waste in adsorptive removal of nitrates from water supplies
Tsitsishvili et al. Combined filter for water treatment
US11944952B2 (en) Removing contaminants from water with adsorbents

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 10855085

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 10855085

Country of ref document: EP

Kind code of ref document: A1