Method for removing heavy metals using an adsorbent

Abstract

A method is presented for removing heavy metal anions from a fluid or gas medium containing metal anions. The method includes providing an adsorbent having deposited therein at least one oxygen-containing compound of at least one metal selected from the group consisting of iron, copper, and aluminum; and contacting a portion of the medium with the adsorbent. The oxygen-containing compound may be incorporated into the carbon by impregnation or dispersion of a suitable precursor of such a compound. The precursor may be further treated to yield the oxygen-containing compound. Such adsorbents are particularly useful for removing arsenic and/or selenium from the environment and may be used in treating drinking water sources.

1 . A method for removing heavy metal anions from a fluid or gas medium containing metal anions, said method comprising the steps of: 
 (1) providing an adsorbent comprising a carbon having a BET surface area greater than about 100 m 2 /g and having deposited therein at least one oxygen-containing compound of at least one metal selected from the group consisting of iron, copper, and aluminum;    (2) contacting a portion of said medium with said adsorbent; and    (3) obtaining a treated medium having a lower concentration of said heavy metal than a concentration of said heavy metal of said medium; wherein said anions contain oxygen; and said oxygen-containing compound is selected from the group consisting of oxides, hydroxides, and combinations thereof.    
     
     
         2 . A method for removing heavy metal anions from a fluid or gas medium containing metal anions, said method comprising the steps of: 
 (1) contacting an adsorbent with a portion of said medium; and    (2) filtering said adsorbent from said medium wherein said adsorbent comprises a carbon having a BET surface area greater than about 100 m 2 /g and having deposited therein at least one oxygen-containing compound of at least one metal selected from the group consisting of iron, copper, and aluminum; wherein said anions contain oxygen; and said oxygen-containing compound is selected from the group consisting of oxides, hydroxides, and combinations thereof.    
     
     
         3 . The method according to  claim 1 , wherein said heavy metal is selected from the group consisting of arsenic, selenium, and combinations thereof.  
     
     
         4 . The method according to  claim 1 , wherein said at least one metal is present at a concentration from about 0.01 to about 50 percent by weight of said carbon.  
     
     
         5 . The method according to  claim 1 , wherein said adsorbent has a micropore volume of greater than about 20 cm 3 /100 g of adsorbent.  
     
     
         6 . The method according to  claim 1 , wherein said adsorbent has a form selected from the group consisting of granule, pellet, sphere, powder, woven fabric, non-woven fabric, mat, felt, block, and honeycomb.  
     
     
         7 . The method according to  claim 1 , wherein said adsorbent is disposed at a point of use.  
     
     
         8 . The method according  claim 7 , wherein said adsorbent is disposed in a fixed bed or fluidized bed.  
     
     
         9 . The method according  claim 7 , wherein said adsorbent is disposed in a section of a water supply piping of a house.  
     
     
         10 . The method according to  claim 8 , wherein said fixed bed comprises a cartridge that is disposed at a water faucet.  
     
     
         11 . The method according to  claim 10 , wherein said cartridge further comprises at least one adsorbent selected from the group consisting of zeolites, ion exchange resins, silica gel, alumina, impregnated carbon and unimpregnated activated carbons.