Adsorption of sodium dodecyl benzene sulfonate from aqueous solution using a modified natural zeolite with CTAB

This paper describes studies of surface modification of a natural Chilean zeolite with cetyl trimethylammonium bromide (CTAB), to investigate the adsorption efficiency for the removal from aqueous solution of an anionic surfactant, sodium dodecyl benzene sulfonate (SDBS), at bench scale. Modification of the zeolite with CTAB (named ZMS) was based on the external cation exchange capacity (ECEC) of 0.11 meq g(-1). The medium pH influences the SDBS ions adsorption rate onto ZMS and the adsorption followed the pseudo-second-order kinetic model. Equilibrium data showed excellent correlation with the Langmuir isotherm model. The adsorption capacities depended on maximum uptakes followed the CTAB concentration or coverage ranging from 40% to 660% of the ECEC. The maximum adsorption capacity of 30.7 mg SDBS g(-1) was obtained at 660% of ECEC value. These data contribute for the understanding of mechanisms involved in zeolite modification and provide same practical clues to improve the adsorption efficiency (uptake capacity) of anionic surfactants. Results were discussed in terms of interfacial and solution chemistry phenomena. (C) 2010 Elsevier Ltd. All rights reserved.