Adsorption of Cr(VI) by material synthesized from red mud and rice husk ash

Abstract

In this work, the efficiency of a material prepared from red mud and rice husk ash (ZRM), in Cr(VI) absorption, without the use of acid to neutralize raw red mud (RM), was examined. The physicochemical characteristics of the obtained material were determined by several methods, including BET nitrogen adsorption, XRD, SEM, and TEM. ZRM was employed in the adsorption of Cr(VI) in solution at 25 o C with a Cr(VI) concentration of 20 ppm. The results showed that the nano particles of material were formed within the size range of 30-50 nm, and that the specific surface area of the material was 70.76 m 2 /g. The conditions of the adsorption process (i.e., the initial pH of the solution, the stirring rate, and the material content) were seen to significantly affect the efficiency of Cr(VI) adsorption at the material's surface. The optimum conditions for Cr(VI) adsorption via ZRM were determined as pH=2, a stirring rate of 300 rpm, and a material content of 10 g/l. With these conditions, the maximum adsorption capacity for Cr(VI) in a solution of ZRM was found to be 23.32 mg/g.