Study of the adsorption and electroadsorption process of Cu (II) ions within thermally and chemically modified activated carbon

Abstract

The aim of this work is to modify the porous texture and superficial groups of a commercial activatedcarbon through chemical and thermal treatment and subsequently study the kinetics of adsorption andelectroadsorption of Cu (II) ion for these carbons.Samples of three activated carbons were used. These were a commercial activated carbon, commercialactivated carbon modified thermically (C-N2-900) and finally commercial activated carbon modifiedchemically C-SO2-H2S-200. The activated carbons were characterized chemically and texturally and theelectrical conductivity of them determined. Different kinetic models were applied. The kinetics of theadsorption and electroadsorption process of the Cu (II) ion fits a pseudo second order model and themost likely mechanism takes place in two stages. A first step through transfer of the metal mass throughthe boundary layer of the adsorbent and distribution of the Cu (II) on the external surface of the activatedcarbon and a second step that represents intraparticle diffusion and joining of the Cu (II) with the activecentres of the activated carbon. Finally, the kinetics of the adsorption process are faster than the kinetics ofthe electroadsorption but the percentage of the Cu (II) ion retained is much higher in the electroadsorptionprocess.