Sorption of phenol from aqueous solution using activated carbon prepared from Manilkara zapota seed

Abstract

The potential of activated carbon prepared from the seeds of Manilkara zapota, an agricultural waste, was assessed for adsorptive dephenolation from aqueous solution. ZnCl2 was used as the activating agent. Batch adsorption experiments were conducted to study the effect of various physicochemical parameters such as initial concentration, dose of adsorbent, initial pH, and temperature. The percentage removal of phenol was found to increase with the decrease in initial concentration of phenol. Maximum removal efficiency of 96% was achieved with 25 mg/L of initial phenol concentration at pH 4.0 and temperature 30ºC. Equilibrium modelling by linearized adsorption isotherms revealed that Freundlich isotherm could well represent the observed data for phenol adsorption on activated carbon as compared to Langmuir isotherm. Thermodynamic studies revealed that the sorption of phenol by activated carbon is an endothermic process, showing increase in sorption at higher temperature. Comparison of various kinetic models based on correlation coefficients revealed that the pseudo second order model, an indication of chemisorption mechanism, fits better the experimental data than the pseudo first order Lagergren model.