Intercalated organo-bentonite as efficient biosorbent for aromatic carboxylic acids from wastewater

Abstract

This study aims to prepare intercalated organo-bentonite using cetylbenzyldimethylammoniumbromide (CBDAB) and investigate its ability for the removal of benzoic (BA) and salicylic (SA) acids from wastewater. The obtained results confirm the intercalation of CBDA into the bentonite interlayer. Several important parameters of SA and BA adsorption onto sodium bentonite (Na-bent) and intercalated bentonite (CBDA-bent) including the adsorbent dosage, contact time, pH, ionic strength, and temperature are investigated in batch mode. Overall, CBDA-bent, which possesses a high specific surface (32 m2/g) area and a pore volume (0.14 cm3/g) demonstrates promising prospects for SA and BA adsorption, reaching 55.2 mg/g and 64.5 mg/g, respectively. The SA and BA are found to primarily interact well through both surface and interlayer processes in basic media. The equilibrium experimental data have been analyzed by Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms; nonetheless the adsorption is well described by the Langmuir model. The influence of contact time on SA and BA uptake is modeled using pseudo second-order, pseudo first-order, intraparticle diffusion, and Boyd kinetic models. An intraparticle diffusion mechanism is found to control the adsorption process, where the internal mass transfer is higher than the external mass transfer. A thermodynamic study shows that the adsorption of both acids is not spontaneous and endothermic. Desorption of SA and BA acids from both Na-bent and CBDA-bent has been performed and the possibilities for reuse investigated.