Equilibrium and kinetic studies of phenol sorption by chitosan coated montmorillonite

Abstract

In order to provide physical support for chitosan and increase the accessibility of the binding sites for sorption process applications, chitosan was coated on the surface of montmorillonite. For the optimization of the sorption of phenol on chitosan coated montmorillonite (CCM), effects of pH, initial concentration and temperature on the sorption of phenol by CCM were investigated. In order to find the sorption characteristics, the isothermal data were applied to Langmuir and Freundlich linear isotherm equation, and the thermodynamic parameters (ΔH, ΔG and ΔS) were also calculated according to the values of binding Langmuir constant KL. The L type sorption isotherm between phenol and CCM suggests a relatively high affinity between the adsórbate and adsorbent, and the mechanism involved in the association of phenol with CCM were protón transfer, hydrogen bonding, London-Van der Waals forces because of lots of the OH and NH2 groups in the chitosan chain. The negative ΔH constant confirmed that the more phenol was adsorbed by CCM at lower temperature and the driving force for sorption process is an enthalpy effect. The kinetics of the sorption process of phenol on CCM were also investigated using the pseudo-first order and pseudo-second order kinetics, results showed that the second order equation model provided the best correlation with the experimental results. It was reached that modification of chitosan with montmorillonite increased the possibility of utilization of chitosan for phenol remo ve from aqueous solution. © 2009 Sociedad Chilena de Química.