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

Fe-based metallic glasses (Fe MGs ) 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 Fe MGs for the removal of azo dye . Synergetic effects between pyrite and Fe MGs improved the removal of Orange II when using an Fe MGs /pyrite mixture, where the reaction rate constant k obs was 0.218 min −1 , which was higher than when using Fe MGs alone (0.114 min −1 ). Orange II was removed at pH 0 ranging from 5.0 to 10.0 in the presence of pyrite, while it was inefficiently removed by Fe MGs alone (10 g/L) at pH 0 10.0. Mechanistic investigations showed that the synergistic effect between Fe MGs and pyrite enhanced the surface corrosion of Fe MGs and accelerated the Fe 3+ /Fe 2+ redox cycle to generate more sorbed Fe 2+ , which was the dominant reactive species during Orange II removal. This study proposes an approach for enhancing the removal of dye wastewater by using Fe MGs to treat mine waste.