Polysulfide intercalated layered double hydroxides for metal capture applications

Patent metadata

Field	Value
Publication number	US-9610538-B2
Application number	US-201514715768-A
Country	US
Kind code	B2
Filing date	May 19, 2015
Priority date	May 20, 2014
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

Polysulfide intercalated layered double hydroxides and methods for their use in vapor and liquid-phase metal capture applications are provided. The layered double hydroxides comprise a plurality of positively charged host layers of mixed metal hydroxides separated by interlayer spaces. Polysulfide anions are intercalated in the interlayer spaces.

First claim

What is claimed is:

1. A polysulfide intercalated layered double hydroxide comprising:
a layered double hydroxide comprising a plurality of positively charged host layers comprising mixed metal hydroxides, wherein the host layers are separated by interlayer spaces; and
polysulfide anions intercalated in the interlayer spaces.

2. The layered double hydroxide of claim 1 , wherein the layered double hydroxide is a magnesium-aluminum layered double hydroxide.

3. The layered double hydroxide of claim 2 , wherein the polysulfide anions have the formula [S x ] 2− , where x=2, 4 or 5.

4. The layered double hydroxide of claim 1 , wherein the polysulfide anions have the formula [S x ] 2− , where x=2, 4 or 5.

5. A method of removing metal from a sample comprising the metal, the method comprising:
exposing the polysulfide intercalated layered double hydroxide of claim 1 to the sample, wherein the metal reacts with the polysulfide anions to form compounds comprising metal-sulfur bonds in the interlayer spaces; and
removing the polysulfide intercalated layered double hydroxide and the compounds from the sample.

6. The method of claim 5 , wherein the sample comprises vaporized Hg which reacts with the polysulfide anions to form HgS.

7. The method of claim 6 , wherein the polysulfide intercalated layered double hydroxide has a Hg capture capacity of at least about 5×10 5 μg/g, as measured by inductively coupled plasma.

8. The method of claim 5 , wherein the sample comprises metal ions which react with the polysulfide anions to form MS x compounds, where x is an integer in the range from 1 to 8.

9. The method of claim 8 , wherein at least 40% by weight of the metal ions are removed from the sample.

10. The method of claim 8 , wherein at least 70% by weight of the metal ions are removed from the sample.

11. The method of claim 8 , wherein the metal ions are Hg 2+ ions, Ag + ions, Cu 2+ ions or a combination thereof.

12. The method of claim 8 , wherein the metal ions are Hg 2+ ions and the polysulfide intercalated layered double hydroxide has a metal ion absorptive capacity of at least 6×10 5 μg/g.

13. The method of claim 5 , wherein the sample comprises uranium-containing ions which react with the polysulfide anions to form compounds having U-S bonds.

14. The method of claim 13 , wherein the uranium-containing ions are uranyl cations.

15. The method of claim 13 , wherein the sample comprises sea water.

16. The method of claim 13 , wherein the sample comprises waste water.

17. The method of claim 16 , wherein the waste water is from a nuclear power plant.

18. A method of making a polysulfide intercalated layered double hydroxide from a layered double hydroxide comprising: a plurality of positively charged host layers comprising mixed metal hydroxides, wherein the host layers are separated by interlayer spaces; and charge-balancing anions within the interlayer spaces, wherein the charge-balancing anions are anion-exchangeable with polysulfide anions, the method comprising: exposing the layered double hydroxide to a solution comprising polysulfide anions, wherein the polysulfide anions undergo anion exchange with the charge-balancing anions in the interlayer spaces.

19. The method of claim 18 , wherein the charge-balancing anions are NO 3 − anions.

20. The layered double hydroxide of claim 1 , further comprising NO 3 − anions intercalated in the interlayer spaces.

21. The method of claim 5 , wherein the layered double hydroxide further comprises NO 3 − anions intercalated in the interlayer spaces.

Assignees

• Univ Northwestern

Inventors

• Kanatzidis Mercouri G
• Ma Shulan

Classifications

• C02F1/288

  using composite sorbents, e.g. coated, impregnated, multi-layered · CPC title

• C02F1/281 Primary

  using inorganic sorbents · CPC title

• B01D53/64 Primary

  Heavy metals or compounds thereof, e.g. mercury · CPC title

• C02F2101/20

  Heavy metals or heavy metal compounds · CPC title

• B01D2258/0283

  Flue gases · CPC title