US Patent 7300586 pH stable activated carbon

An activated carbon composition is disclosed, which includes an activated carbon and a carboxylic acid containing compound. The activated carbon composition is prepared by immersing an activated carbon in an aqueous solution of a carboxylic acid containing compound. The activated carbon composition is used for purifying aqueous solutions by providing a bed of the activated carbon composition and passing the aqueous solution through the bed of the activated carbon composition. The aqueous solution is passed through the bed such that the flow of the aqueous solution to be purified into the bed and the flow of purified aqueous solution from the bed has a pH differential less than ±1 pH.