Phenol adsorption on magnetic biochar derived from olive pomace: Equilibrium, kinetic and thermodynamics

Abstract

In this study, magnetic biochar obtained from pyrolysis of pretreated olive pomace by iron chloride was used as adsorbent to remove phenol and the adsorption capacity of phenol was revealed. Batch experiments were performed as a function of pH, contact time, adsorbent dosage, temperature, and phenol concentration. Moreover, adsorption kinetics and thermodynamics of phenol adsorption onto magnetic biochar were also evaluated in the study. The optimum conditions for maximum adsorption capacity were obtained at pH of 5.7, dosage of biochar 0.14 g and 60 minutes contact time. In this study, three adsorption isotherms, namely Langmuir, Freundlich and Temkin, were applied to fit the equilibrium data of adsorption of phenol onto magnetic biochar. Results showed that correlation coefficients (R2) for three isotherm models decreased with the temperature increment from 20°C to 40°C and the most suitable isotherm model for adsorption was Freundlich. As for kinetics of the adsorption process, the best described model was found as pseudo-second order. In adsorption thermodynamics part, the negative ΔH° and ΔG° values demonstrated that adsorption was exothermic, feasible and was more spontaneous at lower temperatures.