Removal of arsenic from drinking and process water

Abstract

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 - 20 . (canceled) 
     
     
         21 . A method of making a diatomaceous earth-coated hydroxide gel useable for removing arsenic from water, comprising:
 in solution, contacting a precipitating composition with diatomaceous earth; and   adjusting the pH of the solution to form a diatomaceous earth-coated hydroxide-gel.   
     
     
         22 . The method of  claim 21 , wherein the precipitating composition comprises metal salts. 
     
     
         23 . The method of  claim 22 , wherein the metal salts comprise lanthanum chloride. 
     
     
         24 . The method of  claim 23 , wherein the metal salts comprise an iron salt. 
     
     
         25 . The method of  claim 24 , wherein the iron salt comprises ferric chloride. 
     
     
         26 . The method of  claim 22 , wherein the metal salts comprise non-hydroxide metal salts. 
     
     
         27 . The method of  claim 21 , further comprising separating the diatomaceous earth-coated hydroxide-gel from the solution. 
     
     
         28 . The method of  claim 21 , wherein adjusting the pH of the solution comprises adjusting the pH of the solution to between pH 6 and about pH 10.