Sorption of selenium(IV) and selenium(VI) onto synthetic pyrite (FeS2): Spectroscopic and microscopic analyses

► More strong evidences for Se(IV) reduction than Se(VI) on the pyrite surface. ► Reduction of Se(IV) via disproportionation of the surface-bound sulfur. ► Phase image of AFM showed more heterogeneity of Se(IV)-contacted pyrite.