Adsorption studies of Dichloromethane on some commercially available GACs: Effect of kinetics, thermodynamics and competitive ions

The objective of this work was to compare the effectiveness of four commercially available granular activated carbons (GACs); coconut (CGAC), wood (WGAC), lignite (LGAC) and bituminous (BGAC) for the removal of dichloromethane (DCM) from aqueous solution by batch process. Various parameters such as thermodynamics, kinetics, pH, concentration of adsorbate, dosages of adsorbent and competitive ions effect on DCM adsorption were investigated. Maximum adsorption capacity (45.5 mg/g for CGAC) was observed at pH 6.0-8.0. The kinetics data indicate better applicability of pseudo-second-order kinetics model at 25 and 35 deg. C. Freundlich model was better obeyed on CGAC, WGAC, and BGAC, while LGAC followed Langmuir model. The adsorption process for 100 mg/L initial DCM concentration on CGAC was exothermic in nature. The adsorption of DCM on various adsorbents involves physical adsorption process. The adsorption of DCM over a large range of initial concentration on CGAC and LGAC is effective even in presence of ionic salts.