Synergistic effect between pyrite and Fe-based metallic glass for the removal of azo dyes in wastewater

Abstract

Fe-based metallic glasses (FeMGs) are popular reductants for the restoration of wastewater containing various pollutants, but it still suffers from surface passivation and a narrow applicable pH range. In this work, pyrite, an abundant iron sulfide, was used to enhance the reactivity of FeMGs for the removal of azo dye. Synergetic effects between pyrite and FeMGs improved the removal of Orange II when using an FeMGs/pyrite mixture, where the reaction rate constant kobs was 0.218 min−1, which was higher than when using FeMGs alone (0.114 min−1). Orange II was removed at pH0 ranging from 5.0 to 10.0 in the presence of pyrite, while it was inefficiently removed by FeMGs alone (10 g/L) at pH0 10.0. Mechanistic investigations showed that the synergistic effect between FeMGs and pyrite enhanced the surface corrosion of FeMGs and accelerated the Fe3+/Fe2+ redox cycle to generate more sorbed Fe2+, which was the dominant reactive species during Orange II removal. This study proposes an approach for enhancing the removal of dye wastewater by using FeMGs to treat mine waste.