Water purification

Patent metadata

Field	Value
Publication number	US-9617175-B2
Application number	US-201314082654-A
Country	US
Kind code	B2
Filing date	Nov 18, 2013
Priority date	Feb 14, 2007
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

The invention provides an efficient method to purify an aqueous solution, typically mine drainage water, especially of anions and cations present in the aqueous solution as dissolved solids, the anions and cations are removed by treatment with a positively charged extractant having at least eight carbon atoms, whereby an unstable emulsion is formed; the unstable emulsion is allowed to break into an extract phase loaded with the anions and cations, and a water phase depleted in anions and cations; a floc inherently forms in the loaded extractant phase and then the loaded extractant phase and floc are separated from the purified water and treated to remove the anions and cations as concentrated useful products; the treated aqueous phase now reduced in anion and/or cation content is also separated from the emulsion as a purified aqueous solution. The extractant phase is preferably recycled. A continuous water purification process is provided.

First claim

We claim:

1. A method for treating a first aqueous solution to remove at least one metal ion and at least one anion from the first aqueous solution, comprising:
(a) mixing the first aqueous solution with a first water-immiscible extractant phase in a first apparatus to form a first unstable emulsion, wherein the extractant phase comprises:
(i) an extractant comprising a cationic molecule and an anionic base,
(1) wherein the cationic molecule is selected from a quaternary ammonium compound, a quaternary phosphonium compound, and an alkylated monoguanidinium compound, and
(2) wherein the anionic base is selected from CO 3 2− , HCO 3 − , OH − , PO 4 3− , HPO 4 2− , H 2 PO 4 − , HS − , and S 2− ;

(ii) an optional diluent; and
(iii) an optional modifier for modifying phase disengagement,
wherein the extractant forms a colloid with the at least one metal ion and the at least one anion;

(b) separating the first unstable emulsion into a first treated aqueous phase and a first loaded extractant phase, the colloid being present in the first loaded extractant phase.

2. The method of claim 1 , wherein the cationic molecule has a carbon number from at least 18 to about 34.

3. The method of claim 1 , wherein the ratio of the first water-immiscible extractant phase to the first aqueous solution is from about 1:20 to about 20:1 (v/v).

4. The method of claim 1 , wherein the pH of the first aqueous solution prior to mixing with the first water-immiscible extractant phase is from about 2 to about 7.

5. The method of claim 1 , wherein the first aqueous solution is mixed with the first water-immiscible extractant phase for a period of about 12 seconds to about 120 seconds.

6. The method of claim 1 , wherein the level of total dissolved solids in the first aqueous solution is above 2000 ppm, and the level of total dissolved solids in the first treated aqueous phase is less than 250 ppm.

7. The method of claim 1 , wherein the anionic base is OH − , CO 3 2− , or HCO 3 − .

8. The method of claim 1 , wherein the concentration of the extractant in the extractant phase is from 2% to 30%.

9. The method of claim 1 , wherein the concentration of the at least one anion in the first treated aqueous phase is less than 100 mg/L.

10. The method of claim 1 , wherein the extractant phase includes a carbonate/bicarbonate buffer.

11. The method of claim 1 , wherein carbon dioxide (CO 2 ) is produced during the mixing.

12. The method of claim 1 , wherein the at least one metal ion in the first aqueous solution is Ni 2+ , Fe III , Al 3+ , Cu 2+ , Ag + , Zn 2+ , Co 2+ , Co III Fe 2+ , Ca 2+ , Mg 2+ , Cd 2+ , Mn 2+ , Pb 2+ , Hg 2+ , Hg 2 2+ , CH 3 Hg + , and Cr III .

13. The method of claim 1 , wherein the at least one anion in the first aqueous solution is one or more of the group consisting of sulfate, selenate, nitrate, nitrite, phosphate, arsenate, arsenite, bromate, bromide, perchlorate, iodide, chloride, chromate(VI), permanganate, bisulfide, and sulfide ions.

14. The method of claim 1 , further comprising stripping the metal ions in the first loaded extractant phase by:
mixing the first loaded extractant phase with an aqueous acid solution to form a second unstable emulsion; and
separating the second unstable emulsion into a first loaded aqueous acid phase and a first metal ion stripped extractant phase, the first loaded aqueous acid phase containing the at least one metal ion and the first metal ion stripped extractant phase containing the at least one anion.

15. The method of claim 14 , wherein the first loaded aqueous acid phase is further treated by one or more of an oil/water separator, a solid/liquid separator, and an organic odor sorbent, whereby a first metal ion product is obtained.

16. The method of claim 14 , wherein the aqueous acid solution is aqueous sulfuric acid or orthophosphoric acid.

17. The method of claim 14 , further comprising:
mixing the first metal ion stripped extractant phase with an aqueous stripping solution containing an alkali metal cation and an anionic base selected from the group consisting of CO 3 2− , HCO 3 − , OH − , PO 4 3− , HPO 4 2− , H 2 PO 4 − , HS − , and S 2− , to produce a third unstable emulsion;
separating the third unstable emulsion into (i) a regenerated extractant phase stripped of the at least one anion removed from the first aqueous solution and containing the anionic base of the aqueous stripping solution, and (ii) a third aqueous phase containing a salt formed from the alkali metal cation and the at least one anion removed from the first aqueous solution.

18. The method of claim 17 , wherein the third aqueous phase is further treated by one or more of an oil/water separator, a solid/liquid separator, and an organic odor sorbent, to purify and collect the salt formed from the alkali metal cation and the at least one anion.

19. The method of claim 17 , wherein the regenerated extractant phase is recycled to be mixed with the first aqueous solution.

20. The method of claim 1 , further comprising mixing the first treated aqueous phase with a second water-immiscible extractant phase in a second apparatus to form a fourth unstable emulsion having a pH of about 5 to about 9, wherein another colloid is formed; and
separating the fourth unstable emulsion into a fourth treated aqueous phase and a second loaded extractant phase, the colloid being present in the second loaded extractant phase.

21. The method of claim 20 , wherein the second loaded extractant phase is sent to the first apparatus.

22. The method of claim 20 , wherein the colloid in the second apparatus includes Ni 2+ , Co 2+ , Zn 2+ , Fe 2+ , or Mn 2+ ions.

23. The method of claim 20 , further comprising mixing the fourth treated aqueous phase with a third water-immiscible extractant phase in a third apparatus to form a fifth unstable emulsion having a pH of about 8.5 to about 10, wherein a colloid is formed; and
separating the fifth unstable emulsion into a fifth treated aqueous phase and a third loaded extractant phase, the colloid being present in the third loaded extractant phase.

24. The method of claim 23 , wherein the colloid in the third apparatus includes Mn 2+ or Ca 2+ ions.

25. The method of claim 23 , further comprising mixing the fifth treated aqueous phase with a fourth water-immiscible extractant phase in a fourth apparatus to form a sixth unstable emulsion having a pH of about 10.5 to about 12, wherein a colloid is formed; and
separating the sixth unstable emulsion into a sixth treated aqueous phase and a fourth loaded extractant phase, the colloid being present in the fourth loaded extractant phase.

26. The method of claim 25 , wherein the colloid in the fourth apparatus includes Mg 2+ ions.

27. A method for treating a first aqueous solution to remove at least one metal ion and sulfate anions from the first aqueous solution, comprising:
(a) mixing the first aqueous solution with a first water-immiscible extractant phase in a first apparatus to form a first unstable emulsion, wherein the extractant phase comprises:
(i) an extractant comprising a cationic molecule and an anionic base,
(1) wherein the cationic molecule is selected from a quaternary ammonium compound, a quaternary phosphonium compound, and an alkylated monoguanidinium compound, and has a carbon number from at least 18 to about 34, and
(2) wherein the anionic base is selected fro

Assignees

• Battelle Memorial Institute
• Winner Water Services Inc

Inventors

• Monzyk Bruce F
• Von Fahnestock F Michael
• Rose James K
• Conkle H Nick
• Wang Ming
• Chauhan Satya P
• Bruce Ruey K
• Highsmith Tenisha

Classifications

• C02F1/26

  by extraction · CPC title

• B01D17/047

  with separation aids · CPC title

• C02F1/5236 Primary

  using inorganic agents · CPC title

• B01D11/0288

  Applications, solvents · CPC title

• B01D21/01 Primary

  using flocculating agents (for purifying water C02F1/52; for liquid radioactive waste G21F9/10) · CPC title