Enhanced Fenton-like process on Co9S8 catalyst with Mixed-Valence Cobalt(0)/Cobalt(Ⅱ)

• Published in: Separation and purification technology 2025-03, Vol.355, p.129649, Article 129649
• Main Authors: Pei, Yan, Liu, Xun, Cao, Mengbo, Wang, Zijun, Yang, Hongbing
• Format: Article
• Language: English
• Subjects: Advanced oxidation; Co9S8; Germination toxicity tests; Tetracycline; Toxicity assessment
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.129649

[Display omitted] •Improve the degradation efficiency by the cyclic transformation of Co3+/Co2+/Co0.•The excellent normalization kinetic of Co9S8/Co-C is 4 times larger than Co9S8.•S2- acts as an active site that promotes electron transfer and the generation of ROS.•The germination test confirms the system’s low toxicity through practical methods. Peroxymonosulfate (PMS)-based Fenton-like reactions have great potential to revolutionize wastewater treatment, but achieving highly efficient decontamination at low chemical input remains extremely challenging. In this study, a carbon carrier-supported Co9S8 catalyst with Mixed-Valence Cobalt(0)/Cobalt(Ⅱ) was prepared, which enables 70.72 % PMS decomposition-rate and complete, highly efficient tetracycline (TC) removal. Through the cyclic conversion pathways of polyvalent cobalt and the auto-decomposition of PMS, which produced SO4•-, 1O2, •OH, and high-valence metals, the material’s efficiency in degrading TC through PMS activation was effectively enhanced (99.92 %). S2-, as one of the active sites, not only promotes the participation of Co3+/Co2+/Co0 in the generation of reactive oxygen species but also significantly facilitates electron transfer to further increase the catalytic reaction rate. Through metal-chelating agents, it is illustrated that Co2+ directly activates PMS to produce reactive oxygen species (ROS), while Co3+ promotes cycling. The normalized kinetic constant of Co9S8/Co-C (105.6 min−1M−1) was even four times larger than that of Co9S8 (26.4 min−1M−1). Co9S8/Co-C exhibited rapid degradation over a wide pH range and extensive cycling experiments, demonstrating its versatility and stability in various environments. Possible degradation pathways were speculated using liquid chromatography-mass spectrometry (LC-MS). Toxicological evaluations and mung bean germination toxicity tests indicated that the Co9S8/Co-C+PMS system effectively reduced toxicity. It enables the complete degradation of TC while remarkably reducing the toxic intermediates, ensuring that the catalyst is suitable for wastewater treatment applications.