Enhanced adsorptive performance of Cr(VI) onto layered double hydroxide-bentonite composite: Isotherm, kinetic and thermodynamic studies

In this work, cobalt-aluminum-layered double hydroxide (CoAl) and its bentonite composite (Bent-CoAl) were utilized for adsorption of Cr(VI) from water. Incorporation of bentonite into layers of CoAl resulted in significant improvement in the adsorptive performance with increased BET surface area, without damaging LDH structure. The adsorption process was described by Freundlich isotherm and pseudo-second-order kinetic models. The mechanism of Cr(VI) sorption mainly involved electrostatic and chemical interactions with maximum Cr(VI) sorption value of 211.86 mg/g. This suggests that synergistic effect of bentonite into CoAl provided a superior adsorbent for decontamination of heavy metals.