Preparation of new CaFeAl-layered doubled hydroxides adsorbent for Cr(VI) adsorption from polyaluminum chloride residue

In the two-step production of polyaluminum chloride, the insoluble solid in raw material will become waste residue. The landfill could cause pollution of non-point source and groundwater. Meanwhile, reports of Cr(VI) contamination in drinking water due to industrial pollution occur frequently. In this study, a new adsorbent was prepared by calcination of polyaluminum chloride residue. The new adsorbent was characterized, and the adsorption capacity of Cr(VI) in water was analyzed. The analysis results showed that the new adsorbent not only could provide a larger specific surface area (6 times higher than polyaluminum chloride residue) and more active sites, but also could maintain the stability of its structure. The second-order adsorption kinetic model and Langmuir adsorption isotherm model could well describe the adsorption process of Cr(VI) on the new material. The Cr(VI) adsorption by the new adsorbent is a spontaneous endothermic process. Compared with other commonly used adsorbents, the cost of new adsorbent was 1.308 $/kg, and it had obvious economic advantages. This study explored a new way of resource utilization of polyaluminum chloride residue, and the adsorption capacity could still be maintained above 2.6 mg/g after 5 times of regeneration, indicating that the material has engineering application potential. This paper could provide more technical options for environmental protection engineers, provide ideas for environmental researcher, and solve the problem of water pollution by combining with other water treatment technologies. [GRAPHICS]