# US 10,479,703 B2 · Method for reducing arsenic concentration in aqueous solutions

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- Number: US 10,479,703 B2
- Document ID: US10479703B2
- Status: Granted
- Kind: B2
- Application number: 15/317,233
- Filed: 2015-06-12
- Published: 2017-04-27
- Granted: 2019-11-19
- Earliest claimed: 2014-06-13
- Assignees: Imperial College Innovations Limited
- Applicants: Imperial Innovations Limited
- Inventors: Christopher Moffat; Ramon Vilar Compte; Dominik Weiss
- Web page: https://patentgrep.com/patent/US10479703B2

## CPC

- C02F 1/285: {using synthetic organic sorbents}
- B01J 20/223: {containing metals, e.g. organo-metallic compounds, coordination complexes}
- B01J 20/321: {consisting of a polymer obtained by reactions involving only carbon to carbon unsaturated bonds}
- B01J 20/3219: {involving a particular spacer or linking group, e.g. for attaching an active group}
- B01J 20/3265: {with an organic functional group containing a metal, e.g. a metal affinity ligand}
- B01J 20/3425: {of sorbents or filter aids comprising organic materials}
- C02F 1/281: {using inorganic sorbents}
- C02F 1/288: {using composite sorbents, e.g. coated, impregnated, multi-layered}
- C02F 1/72: by oxidation {(C02F1/4672 takes precedence)}
- C02F 1/683: {by addition of complex-forming compounds}
- C02F 2101/103: {Arsenic compounds}
- C02F 2101/105: {Phosphorus compounds}
- C02F 2103/06: Contaminated groundwater or leachate
- C02F 2209/06: pH
- C02F 2303/16: Regeneration of sorbents, filters
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS

## Abstract

Method of reducing the arsenic concentration in an aqueous solution comprising undesired arsenic, which method comprises contacting the aqueous solution with a complex of Formula (I), (Formula (I)) wherein M1 and M2 are the same or different and are independently selected from V, Mn, Ga, Cu, Ni, Co, Fe or Zn; wherein a is 0, or 1, and b is 0, or 1, provided that a+b together must be at least 1; Q is a negatively charged counter ion; n is from 1 to 5; X1 is OH, O, SH or S; L1 is a group selected from —La1-C(O)NR—, —La2-C(O)OR—, —La3-NRC(O)—, La4-OC(O)—, La5-O— or La6-NRO—, wherein La1, La2, La3, La4, La5 and La6 are each C1-6 alkyl, optionally substituted, R is H or C1-6 alkyl optionally substituted; Linker is a polyethylene glycol (PEG) chain with from 1 to 10 repeating units, a C1-16 polyamine chain or a C1-16 alkyl chain; Z is a solid support; L2 to L7 are independently C1-3 alkyl, optionally substituted; and Het1 to Het4 are independently 5 to 14 membered heteroaryl group having at least one N atom and optionally substituted.

## Claims

### Claim 1

A method of reducing the arsenic concentration in an aqueous solution that comprises arsenic, which method comprises contacting the aqueous solution with a complex of Formula I,
wherein M1 and M2 are the same or different and are independently selected from V, Mn, Ga, Cu, Ni, Co, Fe or Zn; wherein a is 0, or 1, and b is 0, or 1, provided that a+b together must be at least 1;
Q is a negatively charged counter ion, wherein the negatively charged counter ion is NO3−, ClO4−, AcO−, PF6−, BF4−, Cl−, BPh4− or Br−;
n is from 1 to 5;
X1 is OH, O, SH or S;
L1 is a group selected from -La1-C(O)NR—, -La2-C(O)OR—, -La3-NRC(O)—, La4-OC(O)—, La5-O— or La6-NRO—, wherein La1, La2, La3, La4, La5 and La6 are each C1-6 alkyl, optionally substituted, R is H or C1-6 alkyl optionally substituted;
Linker is a polyethylene glycol (PEG) chain with from 1 to 10 repeating units, a C1-16 polyamine chain or a C1-16 alkyl chain;
Z is a solid support;
L2 to L7 are independently C1-3 alkyl, optionally substituted; and
Het1 to Het4 are independently 5 to 14 membered heteroaryl group having at least one N atom and optionally substituted.

### Claim 2 (depends on 1)

A method according to claim 1, wherein the method reduces the concentration of arsenic in the aqueous solution to less than about 10 μg L−1.

### Claim 3 (depends on 2)

A method according to claim 2, wherein the method reduces the concentration of arsenic in the aqueous solution to less than about 5 μg L−1.

### Claim 4 (depends on 3)

A method according to claim 3, wherein the method reduces the concentration of arsenic in the aqueous solution to less than about 1 μg L−1.

### Claim 5 (depends on 1)

A method according to claim 1, wherein the solid support is a polystyrene based resin.

### Claim 6 (depends on 1)

A method according to claim 1, wherein the Linker is a polyethylene glycol (PEG) chain with from 1 to 10 repeating units.

### Claim 7 (depends on 6)

A method according to claim 6, wherein the solid support is a polystyrene based resin and the Linker is a polyethylene glycol (PEG) chain with from 1 to 10 repeating units.

### Claim 8 (depends on 1)

A method according to claim 1, wherein one of M1 or M2 is zinc or both M1 and M2 are zinc.

### Claim 9 (depends on 1)

A method according to claim 1, wherein the initial pH of the aqueous solution prior to a point of contact with the complex of Formula I is from about 1 to about 10.

### Claim 10 (depends on 9)

A method according to claim 9, wherein the initial pH of the aqueous solution prior to a point of contact with the complex of Formula I is from about 5 to about 10.

### Claim 11 (depends on 10)

A method according to claim 10, wherein the initial pH prior to a point of contact with the complex of Formula I is about 7.

### Claim 12 (depends on 1)

A method according to claim 1, comprising the additional step of regenerating the complex of Formula I.

### Claim 13 (depends on 12)

A method according to claim 12, wherein the complex of Formula I is regenerated by contacting a complex of Formula I to which arsenic is bound with a solution of an alkali metal salt or an alkali earth metal salt having a pH of from about 7 to about 10.

### Claim 14 (depends on 13)

A method according to claim 13, wherein the solution is of a halide salt of an alkali metal.

### Claim 15 (depends on 14)

A method according to claim 14, wherein the complex of Formula I is regenerated by contacting the complex of Formula I to which arsenic is bound with a NaCl or NaOAc solution having a pH from about 7 to about 10.

### Claim 16 (depends on 1)

A method according to claim 1, further comprising the step of:
contacting the complex of Formula I to which arsenic is bound formed in step (i) with a NaCl or NaOAc solution having a pH of from about 7 to about 10.

### Claim 17 (depends on 1)

A method according to claim 1, comprising the additional step of filtering the aqueous solution comprising arsenic before contacting with a complex of Formula I.

### Claim 18 (depends on 1)

A method according to claim 1, comprising the additional step of filtering the aqueous solution comprising a complex of Formula I to which arsenic is bound after the aqueous solution has been contacted with a complex of Formula I.

### Claim 19 (depends on 1)

A method according to claim 1, comprising the additional step of reacting the aqueous solution comprising arsenic with an oxidising agent before contacting with a complex of Formula I, such that any arsenite present in the aqueous solution is oxidised to arsenate.

### Claim 20 (depends on 1)

A method according to claim 1, wherein the complex of formula I is used in combination with an additional absorbent.

### Claim 21 (depends on 20)

A method according to claim 20, wherein the additional absorbent is an iron oxide absorbent.

### Claim 22 (depends on 1)

A method for providing potable water comprising a method according to claim 1.

### Claim 23

A complex of Formula IV,
wherein Z is a solid support and the linker is a polyethylene glycol (PEG) chain with from 1 to 10 repeating units, a C1-16 polyamine chain or a C1-16 alkyl chain.

### Claim 24 (depends on 23)

A complex according to claim 23, wherein the solid support is a polystyrene based resin.

### Claim 25 (depends on 24)

A complex according to claim 24, wherein the solid support is a polystyrene based resin and the Linker is a polyethylene glycol (PEG) chain with from 1 to 10 repeating units.