Utilization of ferrosilicon from waste carbide slag in enhancing light-driven peroxymonosulfate activation for rapid and clean dyes decolorization

The model of efficient, clean, and cheap collaborative governance has received considerable attention in the treatment of pollution such as wastewater and solid waste. The "waste control by waste" strategy is proposed and put into practice in this work, that is, the ferrosilicon from waste carbide slag is utilized for treating dyes wastewater via the advanced oxidation process (AOP) of ferrosilicon/PMS/light. The main component of ferrosilicon is FeSi and Fe5Si3, which are riched in Fe element and suitable for inducing the AOP reaction. When the ferrosilicon is used in the AOP system, 20 mg L-1 MB can be completely decolorized within 45 min. The excellent performance of the ferrosilicon/PMS/light system is also observed in various wastewater conditions such as solution pH (3-9) and dye types (MB, MO, MG, and CR), which is superior to common PMS/light and other reported system. In addition, the ferrosilicon catalyst can keep the MB removal at nearly 100% in five cycles, and the proportion of its leached iron is always less than 1%, which effectively solves the performance degradation and leaching loss of commonly used zero-valent iron (ZVI) catalyst. In the ferrosilicon/PMS/light system, the SO4?- and 1O2 radicals act as the main active species and their production is due to the redox of iron elements and the self-decomposition of PMS, respectively. Overall, this research progress provides a valuable reference for clean and cheap environmental governance.