Removal of Arsenic from Drinking and Process Water
A method of removing arsenic and heavy metals from water using metal salt hydroxide-gels is provided. The arsenic present in water is adsorbed onto the hydroxide-gels which can effectively be filtered through a diatomaceous earth (DE) filtration bed. The combination of DE mixed hydroxide-gels is also effective in removing arsenic from water and heavy metals from water.
1 . A method of removing arsenic from arsenic-containing water comprising: contacting said water with a precipitating composition comprising a metal salt hydroxide-gel.
2 . The method of claim 1 , further comprising separating said water from said precipitating composition.
3 . The method of claim 2 , wherein said separating is performed using a filter.
4 . The method of claim 3 , wherein said filter is a diatomaceous earth filter bed coated with a metal salt hydroxide-gel.
5 . The method of claim 1 , wherein said metal salt hydroxide-gel is formed prior to contacting said water with said precipitating composition.
6 . The method of claim 1 , wherein the pH of the precipitating composition and arsenic-containing water is adjusted to form a metal salt hydroxide-gel after contacting the precipitating composition and said water.
7 . The method of claim 3 , wherein said filter is selected from the group consisting of: diatomaceous earth, cellulose, and perlite.
8 . A method of removing heavy metals from heavy metal-containing solution comprising: contacting said solution with a metal salt hydroxide-gel; and passing said solution through a filter.
9 . The method of claim 8 , wherein said metal salt hydroxide-gel comprises lanthanum and iron.
10 . The method of claim 8 , wherein said filter is a diatomaceous earth filter bed.
11 . The method of claim 8 , wherein said filter is a diatomaceous earth filter bed coated with a metal salt hydroxide-gel.
12 . A composition for removing arsenic or heavy metal from arsenic- or heavy metal-containing water comprising: diatomaceous earth, a lanthanum salt and an iron salt.
13 . The composition of claim 12 , wherein said lanthanum salt and iron salt are chlorides.
14 . The composition of claim 12 , wherein said metal is arsenic.
15 . The composition of claim 12 , wherein said metal is a heavy metal.
16 . A method of using the composition of claim 12 , comprising mixing the precipitating composition with arsenic- or heavy metal-containing water and adjusting the pH so that a metal salt hydroxide-gel is formed.
17 . A method of making a diatomaceous earth-coated hydroxide-gel comprising: contacting a precipitating composition with diatomaceous earth; and adjusting the pH to form a diatomaceous earth-coated hydroxide-gel.
18 . A method of making a diatomaceous earth-coated hydroxide-gel comprising: contacting metal salts with diatomaceous earth, forming a composition; and aging the composition.
19 . The method of claim 18 , further comprising separating the solid composition from the liquid.
20 . The method of claim 18 , further comprising contacting arsenic-containing water with the composition; and adjusting the pH of the resulting composition to form a diatomaceous-coated gel.