Amorphous and porous alkali metal chalcogenides for remediation applications

1. An amorphous metal chalcogenide having the formula A 2x Sn x Sb 3-x Q 6 , wherein x is in the range from 0.8 to 1, A is an alkali metal element, and Q is S or Se.

2. The amorphous metal chalcogenide of claim 1 , wherein Q is S.

3. The amorphous metal chalcogenide of claim 1 , wherein A is K or Cs.

4. The amorphous metal chalcogenide of claim 1 , wherein the metal chalcogenide has the formula K 2x Sn x Sb 3-x S 6 , Cs 2x Sn x Sb 3-x S 6 , or K 2x Sn x Sb 3-x Se 6 .

5. A porous material comprising a chalcogenide having the formula A x′ M y M′ z Q m , where A is an alkali metal element or a mixture of two or more alkali metal elements; M and M′ are main group metal elements or elements from groups 14 or 15 of the periodic table of the elements; Q is S, Se or Te; x′, y, and z are independently selected from values in the range from 0 to 10, and m is in the range from 1 to 20, wherein the material includes pores having pore sizes in the range from 200 nm to 10 μm.

6. The porous material of claim 5 , wherein the material includes pores having sizes of at least 10 μm.

7. The porous material of claim 5 , wherein the material includes pores having sizes of at least 100 μm.

8. The porous material of claim 5 , wherein M is Sn and M′ is Sb.

9. The material of claim 5 , wherein the chalcogenide has the formula (AB) 2x Sn x Sb 3-x Q 6 , wherein x is in the range from 0.8 to 1, A and B are two different alkali metal elements, and Q is S or Se.

10. The material of claim 9 , wherein Q is S.

11. The material of claim 10 , wherein A is K or Cs and B is Li, Na, or K.

12. The material of claim 9 , wherein the chalcogenide has the formula Cs 2-x K x Sn x Sb 3-x S 6 or Na 2-x K x Sn x Sb 3-x S 6 .

13. The material of claim 12 , wherein the chalcogenide has the formula CsKSnSb 2 S 6 or NaKSnSb 2 S 6 .

14. A method of removing metal ions from a sample, the method comprising:

exposing a liquid- or vapor-phase sample comprising metal ions or metal vapors to the porous material of claim 5 , whereby the metal ions undergo ion exchange with the chalcogenide; and

removing the porous material from the sample.

15. The method of claim 14 , wherein the metal ions are transition metal ions.

16. The method of claim 14 , wherein the metal ions are radioactive.

17. The method of claim 14 , wherein the sample comprises waste water from a nuclear power plant, waste water from a municipal water treatment plant, water from a municipal drinking water source, or water from a natural body of water.

18. The method of claim 14 , wherein the metal ion is Hg 2+ , Ag + , Co 2+ , Pb 2+ , or Cd 2+ .

19. A method of making the porous chalcogenide, the method comprising:

mixing an amorphous metal chalcogenide having the formula A x′ M y M′ z Q m , where A is an alkali metal element; M and M′ are main group metal elements or elements from groups 14 or 15 of the periodic table of the elements; Q is S, Se or Te; x′, y, and z are independently selected from values in the range from 0 to 10, and m is in the range from 1 to 20, with an inorganic halide salt having the formula BX, where X is a halogen and B is an alkali metal element, and further wherein A and B may be the same element or different elements;

melting the amorphous metal chalcogenide and the inorganic halide salt to form a homogeneous molten mixture;

solidifying the molten mixture to form a composite material comprising particles of a first phase comprising the inorganic halide salt in a matrix of a second phase comprising the amorphous metal chalcogenide having the formula A x′ M y M′ z Q m ; and

extracting the first phase from the composite material.

20. A method of making the porous chalcogenide, the method comprising:

mixing an amorphous metal chalcogenide having the formula A 2x Sn x Sb 3-x Q 6 , wherein x is in the range from 0.8 to 1, A is an alkali metal element, and Q is S or Se, with an inorganic halide salt having the formula BX, where X is a halogen and B is an alkali metal element;

melting the amorphous metal chalcogenide and the inorganic halide salt to form a homogeneous molten mixture;

solidifying the molten mixture to form a composite material comprising particles of a first phase comprising the inorganic halide salt in a matrix of a second phase comprising the amorphous metal chalcogenide of claim 1 ; and

extracting the first phase from the composite material.

21. The method of claim 20 , wherein the metal chalcogenide has the formula A 2x Sn x Sb 3-x Q 6 , wherein x is in the range from 0.8 to 1, A is K or Cs and Q is S or Se; the inorganic halide salt is a lithium halide salt, sodium halide salt, or a potassium halide salt; and the porous material comprises a chalcogenide having the formula (AB) 2x Sn x Sb 3-x Q 6 , wherein x is in the range from 0.8 to 1, B is Li, Na, or K.