Use of CaCl2 modified bentonite for removal of Congo red dye from aqueous solutions.

Abstract CaCl 2 modified bentonite (BCa 2+ ), a clean and cost-effective adsorbent with a basal spacing of 15.43 A, was prepared for the removal of Congo red dye from water. It was effective for the removal of Congo red with a high adsorption capacity, and the adsorption was favored over a broad pH range (5–10). The pseudo-second-order kinetic model provided the best correlation of the experimental data. Adsorption isotherms indicated that sorption took place at specific homogeneous sites within the adsorbent. Furthermore, BCa 2+ showed higher sorption capacity compared with other common materials used as adsorbents for Congo red dye. The results showed that BCa 2+ could be employed as a low-cost material for the removal of Congo red from aqueous solutions.