Removal of catechol from aqueous solutions by adsorption onto organophilic-bentonite

Organophilic-bentonite, produced by exchange of cetyltrimethylammonium cation for metal cations on the bentonite, was exploited as adsorbent for removal of catechol from aqueous solutions using batch technique. The dependence of removal on various physico-chemical parameters, such as contact time (1-250 min), concentration (0.8-15.3 mmol L-1), temperature (30, 40, 50 +/- 1 degrees C and pH (5-12) of the adsorptive solution were investigated. Obtained results show that catechol could be removed efficiently (similar to 100%) at pH values >= 9.9. The uptake process follows first-order rate kinetics and the equilibrium data fit well into the Langmuir and Freundlich adsorption isotherms over a wide range of concentration (1-10 mmol L-1). The magnitude of change of free energy (Delta G degrees), enthalpy (Delta H degrees) and entropy (Delta S degrees) were determined. (c) 2007 Elsevier B.V. All rights reserved.