One-step synthesis of magnetic activated carbons for methylene blue dye removal: activation conditions and adsorption studies

Abstract

Magnetic activated carbon (MAC) was prepared from palm kernel shell by one-step synthesis using zinc chloride and ferric chloride. The effects of process variables, namely activation temperature and time on carbon yield, methylene blue (MB) adsorption, and magnetic recovery were investi-gated. The synthesis conditions were evaluated by response surface methodology. The MACs were characterized for yield, specific surface area, morphology, and magnetic percentage. The suitable process conditions for activation were found to be 600°C and 2 h, which resulted in activated carbon with 53% yield, maximum MB capacity of 84.7 mg/g, and magnetic recovery of 96.3%. The MB adsorption is mainly influenced by the specific surface area of MAC. Isotherm and kinetics models were employed to examine the adsorption data. The Langmuir model gave the best conformity, suggesting monolayer adsorption of MB molecules. The Dubinin–Radushkevich model proposed that the process may be controlled by physisorption, while the adsorption rate obeyed the pseudo-second-order model. The one-step synthesis using a composite activating agent can simplify the preparation process and yields a promising MAC for dye removal from water.