Process for producing a nanoscale zero-valent metal
View Patent ↗This invention describes a process for producing a nanoscale zero-valent metal, including reduction of a metal ion solution with a dithionite compound, wherein the reduction is carried out under alkaline conditions under substantially an inert atmosphere. A nanoscale zero-valent metal obtainable by this process, and having a new crystalline form, is also described. The nanoscale zero-valent metal produced by the process of the invention is preferably iron, and is advantageously used for the remediation of contaminated water.
1. A process for producing a nanoscale zero-valent metal, said process including reduction of a metal ion solution with a dithionite compound, wherein said reduction is carried out under alkaline conditions and under a substantially inert atmosphere.
2. The process of claim 1 , wherein said metal ion is selected from the group consisting of: iron, nickel, zinc, tin, copper, silver, gold, lead, cadmium, mercury, cobalt, molybdenum, chromium, platinum, palladium and phosphorus.
3. The process of claim 1 , wherein said metal ion is selected from the group consisting of: iron, copper, gold, platinum, palladium and silver.
4. The process of claim 1 , wherein said metal ion is selected from the group consisting of: iron, copper and silver.
5. The process of claim 1 , wherein said metal ion is iron.
6. The process of claim 5 , wherein said metal ion solution is a ferrous (Fe II) solution.
7. The process of claim 6 , wherein said ferrous solution is an aqueous solution.
8. The process of claim 6 , wherein said ferrous solution is an aqueous solution comprising a ferrous salt selected from the group consisting of FeSO4, FeCl2, FeBr2, FeI2, Fe(NO3)2, FeCO3, Fe3(PO4)2 and a mixture of any thereof.
9. The process of claim 6 , wherein said ferrous solution is an aqueous solution of FeSO4 or FeCl2.
10. The process of claim 1 , wherein said dithionite compound is a metal salt of dithionite.
11. The process of claim 1 , wherein said dithionite compound is a compound selected from Na2S2O4, Li2S2O4, K2S2O4, MgS2O4, CaS2O4 or mixtures thereof.
12. The process of claim 1 , wherein said dithionite compound is Na2S2O4.
13. The process of claim 1 , wherein said metal ion solution has a pH in the range of about pH 9 to about pH 11.
14. The process of claim 1 , wherein said metal ion solution has a pH of about pH 10.
15. The process of claim 1 , wherein said alkaline conditions are provided by including a hydroxide compound in said metal ion solution.
16. The process of claim 15 , wherein said hydroxide compound is selected from the group consisting of LiOH, NaOH, KOH, Mg(OH)2, Ca(OH)2 and a mixture of any thereof.
17. The process of claim 15 , wherein said hydroxide compound is NaOH.
18. The process of claim 1 , wherein said process is carried out under a substantially inert atmosphere.
19. The process of claim 18 , wherein said substantially inert atmosphere is provided by nitrogen, argon or a mixture thereof.
20. A nanoscale zero-valent metal obtained by a process according to claim 1 .
21. The nanoscale zero-valent metal according to claim 20 , which is nanoscale zero-valent iron (ZVI).
22. The nanoscale zero-valent metal according to claim 20 , having an average primary particle size of about 0.5 nm to about 3000 nm.
23. The nanoscale zero-valent metal according to claim 20 , having an average aggregate particle size of about 0.1 μm to about 100 μm.
24. The nanoscale zero-valent metal of claim 20 including nanoscale particles of crystalline platelets, each said crystalline platelet including said zero-valent metal.
25. The nanoscale zero-valent metal of claim 24 , wherein said crystalline platelets include metal particles imbedded in a sulfite hydrate crystal matrix.
26. The nanoscale zero-valent metal according to claim 24 , which is iron.
27. The nanoscale zero-valent metal according to claim 24 , wherein said nanoscale particles of crystalline platelets have an average primary particle size in the range of about 0.1 to about 3000 nm.
28. The zero-valent metal according to claim 20 , which is coated with a layer of palladium or platinum.
29. A process for treating a material contaminated with an organic contaminant, said process including the step of contacting the material with a zero-valent metal according to claim 20 .
30. The process of claim 29 , wherein said organic contaminant is a halogenated organic compound (HOC), a nitroaromatic compound, or a mixture thereof.
31. The process of claim 29 , wherein said zero-valent metal is in the form of a colloidal suspension.
32. The process of claim 29 , wherein said contaminated material is contaminated water.