Equilibrium and kinetics studies of 2,4,6-trichlorophenol adsorption onto activated clay

In the present study, activated clay was used as adsorbent for the kinetics of 2,4,6-trichlorophenol (TCP) adsorption from aqueous solution in a batch system. Experiments were carried out as a function of solution pH (2–12), solute concentration (30–220 mg/L), and temperature (30–50 °C). The equilibrium adsorption data of TCP on activated clay were analyzed by Langmuir, Freundlich and Temkin isotherm models. The results indicate that the Freundlich model provides the best correlation of the experimental data. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to analyze the kinetic data obtained at different concentrations. Among the kinetic models studied, the pseudo-second-order was the best applicable model to describe the adsorption of TCP onto activated clay. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of adsorption. Adsorption of TCP is exothermic reaction with ΔH° at −9.37 kJ/mol.