ADSORPTION OF Cr(VI) FROM AQUEOUS SOLUTION USING CARBON-MICROSILICA COMPOSITE ADSORBENT

Abstract

In this work, Microsilica, one kind of industry solid waste material, was utilized firstly to prepare a carbon-Microsilica composite adsorbent from a partial carbonization, mixture and sulfoxidation process and was proposed for the removal of Cr(VI) from solutions.The surface chemistry characteristics of the prepared adsorbent were analysis by XPS and FT-IR.The characterization results indicated that an abundant of oxygen functional groups, such as hydroxyl, carboxyl and sulfonic groups, were introduced into the surface of the prepared composite adsorbent.Meanwhile, the adsorption characteristics of Cr(VI) onto the adsorbent in aqueous solutions was studied as a function of solution pH, ionic strength, contact time, and temperature.The results showed that Cr(VI) adsorption onto the adsorbent is strongly dependent on pH and, to a lesser extent, ionic strength.Kinetics data were found to follow the pseudo-second-order kinetic model while the adsorption data corresponded to L-shape adsorption isotherm which corresponds to the classification of Giles.Activation thermodynamic parameters, such as activation enthalpy (DH*), activation entropy (DS*), activation Gibbs free energy (DG*) and activation energy (E a ), have been evaluated and the possible adsorption mechanism also was suggested.