Activated carbon modification resulting in an enhanced Cr(VI) removal

Abstract

Two modification methods are used to enhance the adsorption properties of Cr(VI) of several activated carbons (AC). AC performance from brewer's spent grain (BSG) is compared with two commercials ACs: Norit GAC 1240 and Filtrasorb F400. The first modification consists of an oxidation of the surface using acidic and basic reagents. Elemental analysis reveals the oxidation of AC, but a removal of surface groups deteriorates adsorption properties. The second modification incorporates a copolymer with a quaternary ammonium end group on the surface of the AC. After copolymer modification a significant increase of nitrogen functionalities (+10%) is realised. An outspoken improvement (a factor of 5) in adsorption capacity and kinetics are proven to be solely caused by the copolymer. No synergic effect is found. Unmodified ACBSG is proven to exhibit the fastest adsorption kinetics for Cr(VI), but Cr tot is removed fasted by copolymerised AC.