POTASSIUM ACETATE – COCONUT SHELL ACTIVATED CARBON FOR ADSORPTION OF BENZENE AND TOLUENE: EQUILIBRIUM AND KINETIC STUDIES

Abstract

A lot of concern has been raised over the presence of toxic volatile organic compounds (VOCs) that causes serious pollution in the air and aqueous media which affects human health due to their carcinogenicity, toxicity and production of secondary pollutants that are more toxic. In this work, coconut shells were used as precursor for the production of activated carbon via chemical activation with potassium acetate (PAAC) for benzene and toluene adsorption. The prepared carbon was characterized with scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and BET surface area analysis. Adsorption studies have been carried out for benzene and toluene adsorption on the carbons at different concentrations between 50 to 250 mg/L. The heterosporous carbon has surface area of 622 m 2 /g that gave high removal efficiencies of 79% and 82% for benzene and toluene, with 32% yield. The equilibrium data were fitted using Langmuir, Freundlich, and Temkin isotherms models where all the models have their R 2 > 0.94. The Langmuir isotherm was found to be the best fitted model with maximum adsorption capacity of 192 mg/g and 227 mg/g for benzene and toluene respectively. The equilibrium parameter (R L ) proposed by Webber and Chakkravorti has obtained values between 0 and 1 which confirm the favourability of the fitted Langmuir isotherm model. The adsorption kinetics was observed to obey the pseudo-second-order kinetic model. The synthesized PAAC can effectively be utilized for the remediation of organic pollutants such as VOCs in the environment through sustainable processes.