Adsorption of As(III) from aqueous solutions using MnO2 strengthened WTRs-chitosan beads made by homogenous method with freeze-drying

Abstract

Although the removal of arsenic from water using chitosan-WTRs adsorbent made by the embedding method has been extensively studied, the adsorption capacity is significantly lower than that of origin WTRs. In this paper, the WTRs-chitosan beads made by homogeneous method (WCB) were used as effective As(III) adsorbents. In order to obtain a better oxidation ability, MnO2 was added to WCB to make Mn-WCB, which was compared with WCB through various experiments to verify the optimization effect. Both adsorbents have carried out a variety of characterization and adsorption efficiency experiments. The physicochemical properties and adsorption capacities of WCB and Mn-WCB were compared, and the adsorption mechanism of Mn-WCB was analyzed. Under neutral conditions, the maximum adsorption capacity estimated according to the Langmuir isotherm model were 28.607 mg/g and 36.911 mg/g, respectively. By comparison, adding manganese dioxide to WCB can effectively increase the adsorption capacity and enhance the regeneration performance, also the pore structure and acid resistance have been improved. The experimental results proved that both WCB and Mn-WCB are good As(III) adsorbents, and Mn-WCB was obviously better than WCB in terms of adsorption capacity and structure, indicating that the addition of MnO2 in WTR-chitosan beads is an effective optimization method for As(III) removal.