Preparation of a novel MnO2/red mud composites to enhance arsenic removal

Red mud (RM), an industrial solid waste generated by the alumina industry, is rich in Fe2O3, Al2O3, and SiO2, and has excellent potential for use as a cheap and economical support and as an adsorbent. In this work, a coprecipitation method was used to load MnO2 on RM as an adsorbent (MnRM) to remove As(V) and As(III) from water. The aim was to fully utilize the oxidative properties of MnO2 and the adsorption capacity of Fe-Al oxides/hydroxides in RM to enhance the As(V) and As(III) capacity in water. The experimental data proved that the adsorption performance of MnRM was much better with adsorption capacities of 31.57 mg/g and 39.32 mg/g for As(V) and As(III), which were 11.29 and 5.71 times higher than that of the raw RM, respectively. Meanwhile, the adsorption capacities of MnRM were also much higher than that of MnO2 for As(V) (18.90 mg/g) and As(III) (27.97 mg/g). The excellent adsorption performance of MnRM makes it ideal for the treatment of As(V) and As (III) contaminated wastewater.