Preparation of sulphate aluminate cement amended bentonite and its use in heavy metal adsorption

Abstract The development of environment friendly and practically feasible technologies or adsorbents to treat water pollution due to heavy metals is urgently required. Herein, Sulphate aluminate cement - bentonite (SAC-bentonite) composites were synthesized and used as low-cost and high-efficiency adsorbents to remove Cr3+, Pb2+, and Cd2+ from aqueous solution. The characteristics of SAC-bentonite were analyzed via X-ray diffraction (XRD) and scanning electron microscopy (SEM). Effects of the amount of adsorbent, solution pH, and contact time on the adsorption performance of SAC-bentonite were also studied. The adsorption mechanism was analyzed via XRD, X-ray photoelectron spectroscopy (XPS), and SEM. The results demonstrate that the adsorption capacities of SAC-bentonite for Cr3+ were similar to that of pure bentonite or pure SAC, while the adsorption capacities for Pb2+ and Cd2+ were significantly higher than those for bentonite or SAC. When the ratio of bentonite to SAC was 1:1, the removal efficiency of SAC-bentonite for Cr3+, Pb2+, and Cd2+ was 99.956%, 99.838%, and 99.717%, respectively. The adsorption kinetics was well described by Pseudo-second-order equation.