锰氧化物负载施氏矿物去除酸性矿山废水中As(III)的性能及机理

Schwertmannite is a natural adsorbent of As, but it application for As(III) removal from acidic condition was restricted since the weak adsorption capacity and lack of oxidation ability. In this study, manganese oxide coated schwertmannite (MnO_x@Sch) was successfully synthesized by using liquid-phase precipitation method and the effects of manganese concentration, initial pH and co-exist ion on As(III) removal were studied. The adsorption kinetics combined with XPS, FTIR and TEM were used to investigate the mechanism of As(III) removal by MnO_x@Sch. The results show that when the initial pH was 3, the dosage was 0.5 g•L^-1 and original As(III) concentration was 1 mg•L^-1, the residual As concentration was only 2.42~3.38 μg•L^-1 after reaction. The effect of initial pH on the removal of As(III) by MnO_x@Sch was slight and was significantly inhibited in the presence of H₂PO₄^-. The process of As(III) removal by MnO_x@Sch well fits the pseudo-second order kinetic and intraparticle diffusion model. Results of the chemical components analysis in liquid and solid phase reveal that the removal mechanism of As(III) by MnO_x@Sch includes As(III) oxidation, electrostatic adsorption, complexation and ligand-exchange. The results could provide theoretical basis for the application of schertmananite in the treatment of arsenic pollution in acid mine drainage.