Electrochemically enhanced adsorption of phenol on activated carbon fibers in basic aqueous solution

Abstract

Electrosorption isotherms and thermodynamics of phenol on activated carbon fibers (ACFs) in basic solution, as well as the factors (bias potential, initial concentration, and electrolyte) affecting adsorption/electrosorption kinetics, were investigated. The kinetics, which followed the Lagergren adsorption rate law, exhibited a variety of responses depending on bias potential, initial concentration, and electrolyte. The electrosorption isotherms were in agreement with the classical models of Langmuir and Freundlich, but the former gave more satisfactory correlation coefficients. With electrosorption at a bias potential of 700 mV from the basic solution, a nearly 10-fold enhancement of maximum adsorption capacity was achievable. The electrosorption free energy ( Δ G ads ), enthalpy ( Δ H ads ), and entropy ( Δ S ads ) of phenol on the ACFs were calculated from adsorption isotherms at different temperatures. The results indicated that electrosorption of phenol in basic solution was spontaneous and exothermic. Furthermore, it was assessed that electrosorption occurred by dipole–dipole interaction with Δ H ads of − 20.14 kJ mol −1 besides suppositional electrostatic interaction.