Preparation and characterization of activated carbon from cotton stalk by microwave assisted chemical activation-Application in methylene blue adsorption from aqueous solution

The activated carbon prepared from cotton stalk with ZnCl2 as activation was investigated under microwave radiation. Effects on the yield and adsorption capacities of activated carbon were evaluated then, such as, microwave power, microwave radiation time and the impregnation ratio of ZnCl2. It indicated that the optimum conditions were as follows: microwave power of 560W, microwave radiation time of 9 min and the impregnation ratio of ZnCl2 was 1.6 g/g. Iodine number, amount of methylene blue adsorption and the yield of activated carbon prepared under optimum conditions were 972.92 mg/g, 193.50 mg/g and 37.92%, respectively. Laboratory prepared activated carbons were characterized by pH(ZPC), SEM, FT-IR, S-BET and pore structural parameters. Then they were used as adsorbent for the removal of methylene blue from aqueous solutions under varying conditions of initial concentration, carbon dosage and pH. It indicated that Langmuir isotherm was fitter than Freundlich isotherm and Temkin isotherm. (C) 2008 Elsevier B.V. All rights reserved.