Adsorption Thermodynamics and Kinetics of p-Xylene on Activated Carbon

A good activated carbon adsorbent, KC-8, was used to remove residual p-xylene (PX) effectively after the extraction process of treating pure terephthalic acid (PTA) wastewater. The adsorption thermodynamics and kinetics of PX on activated carbon KC-8 were investigated completely and systematically. A series of adsorption equilibrium experiments were conducted under temperatures of (313.15, 323.15, and 333.15) K. The adsorption equilibrium data were fitted to Langmuir and Freundlich isothermal equations. The results showed that the adsorption equilibrium data were agreed with the Freundlich isothermal equation well. Thermodynamic analysis suggested Delta H > 0, Delta G < 0, and Delta S > 0. The adsorption of PX on KC-8 was a spontaneous physical and endothermic adsorption process. Kinetic studies indicated that the adsorption process of PX on activated carbon KC-8 could be described well by the pseudosecond-order kinetic model, and particle diffusion was the main rate-controlling step in the adsorption process.