Metal-organic frameworks for adsorption of liquid phase compounds
The present invention provides for the use of a metal-organic framework (MOF) in removing particular chemical species or compounds, in particular oxy-anions, from a liquid or liquid stream. In some embodiments, the MOF is a Zr-based MOF, such as NU-1000, and the oxy-anions that are removed include, include, for example, oxy-anions of selenium, including selenite (SeO 3 2− ) and selenate (SeO 4 2− ); oxy-anions of antimony, including oxy-anions in either the Sb[III] (antimonite) or the Sb[V] (antimonate) redox state; and oxy-anions of lead, including oxy-anions in either the Pb[II] or the Pb[IV] redox state, such as Pb(OH) 6 2− , Pb(OH) 6 4− , PbO 3 2− , and PbO 2 2− . The Zr-based MOF, including NU-1000 can be used to remove these oxy-anions from various liquid streams in industrial processes such as a nuclear and fossil fuel power plants, including the latter's flue gas desulfurization system.
1. A method for reducing the concentration of an oxy-anion from a liquid stream, comprising:
contacting a liquid stream comprising an oxy-anion with a zirconium-based metal-organic framework; and
complexing the oxy-anion with the metal-organic framework wherein said complexing comprises η 2 μ 2 binding, thereby reducing the concentration of the oxy-anion in the liquid stream.
2. The method of claim 1 , wherein the oxy-anion comprises a selenium oxy-anion.
3. The method of claim 2 , wherein the selenium oxy-anion comprises selenate.
4. The method of claim 3 , wherein the metal-organic framework comprises NU-1000 and the adsorption capacity of the NU-1000 is approximately 85 mg selenate/g metal-organic framework or less.
5. The method of claim 2 , wherein the selenium oxy-anion comprises selenite.
6. The method of claim 5 , wherein the metal-organic framework comprises NU-1000 and the adsorption capacity of the NU-1000 is approximately 95 mg selenite/g metal-organic framework or less.
7. The method of claim 1 , wherein the liquid stream further comprises a competing chemical species.
8. The method of claim 7 , wherein the oxy-anion comprises a selenium oxy-anion and the competing chemical species comprises an oxy-anion of sulfur.
9. The method of claim 7 , wherein the oxy-anion comprises a selenium oxy-anion and the competing chemical species comprises an oxy-anion of boron.
10. The method of claim 1 , wherein the metal-organic framework comprises NU-1000.
11. The method of claim 10 , wherein the crystalline size of the NU-1000 is approximately 75-1200 nm.
12. The method of claim 10 , wherein the crystalline size of the NU-1000 is up to approximately 1500 nm.
13. The method of claim 1 , wherein the concentration of the oxy-anion in the liquid stream after said complexing is less than 20 ppb.
14. The method of claim 1 , wherein the oxy-anion comprises an antimony oxy-anion.
15. The method of claim 14 , wherein the antimony oxy-anion comprises Sb[V].
16. The method of claim 14 , wherein the antimony oxy-anion comprises Sb[III].
17. The method of claim 14 , wherein the metal-organic framework comprises NU-1000 and the adsorption capacity of the NU-1000 is approximately 260 mg Sb(OH) 6 /g metal-organic framework or less.
18. The method of claim 1 , wherein the oxy-anion comprises a lead oxy-anion.
19. The method of claim 18 , wherein the lead oxy-anion comprises Pb(OH) 6 2 .
20. The method of claim 18 , wherein the lead oxy-anion comprises Pb(OH) 6 4− .
21. The method of claim 18 , wherein the lead oxy-anion comprises PbO 3 2− .
22. The method of claim 18 , wherein the lead oxy-anion comprises PbO 2 2− .