Batch adsorption of cephalexin antibiotic from aqueous solution by walnut shell-based activated carbon

The batch adsorption experiments were investigated for the adsorption of cephalexin (CFX) antibiotic on walnut shell activated carbon (AC). The adsorbent was prepared by chemical activation method in the presence of ZnCl2. Several adsorption parameters including the adsorbent dosage, the initial CFX concentration, contact time, temperature, and pH were studied. The adsorption isotherm was analyzed by different isotherm models. It was found that the Freundlich and Toth models provided the best fit for the experimental data for two and three parameter models, respectively. The maximum adsorption capacity was obtained 233.1 mg/g based on the Langmuir model. The kinetic data were well represented by pseudo-second order model. Thermodynamics analysis showed endothermic nature of CFX adsorption on walnut shell AC under examined conditions. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.