Batch adsorptive removal of benzoic acid from aqueous solution onto modified natural vermiculite: Kinetic, isotherm and thermodynamic studies

The performance of modified vermiculite for the batch adsorption of benzoic acid from aqueous solution was studied. Grinding treatment enhanced the ion exchange ability of natural vermiculite. Cetyltrimethylammonium bromide improved the adsorptive characteristics of ground vermiculite better than cetylpyridinium bromide. The optimum conditions were obtained as the adsorbent dosage of 0.5 g/50 mL, initial pH of 3.5 and contact time of about 140 min. The pseudo-second-order model provided a good correlation of the kinetic data. The equilibrium data were well described by the Langmuir and Temkin equations. Thermodynamically, it was concluded that the process is endothermic and spontaneous.