Visible light photocatalytic enhanced heterogeneous cobalt catalyzed peroxymonosulfate synergistic process to degradation atrazine: Efficiency, influencing factors, by-products removal and mechanism

This study developed a novel heterogeneous Vis-Photo+Fenton-like system by integrating visible-light-responsive Co 3 O 4 /TiO 2 photocatalysis with peroxymonosulfate (PMS) activation for efficient atrazine (ATZ) degradation. The synergistic process achieved complete ATZ removal within 60 min under near-neutral pH (6.9), outperforming individual Fenton-like (39 %) and photocatalytic (24 %) processes. Key factors influencing the degradation efficiency included light sources (UV > visible), pH (optimal at 6.9), catalyst dosage (0.01 g Co 3 O 4 /TiO 2 ), and PMS:ATZ molar ratio (1:2). The system exhibited a synergistic coefficient of 5.03 (degradation) and 1.97 (mineralization), attributed to enhanced radical generation and accelerated Co 3+ /Co 2+ redox cycling through photoinduced electron transfer. Intermediate analysis revealed dealkylation, dechlorination, and oxidation pathways, with reduced toxicity of by-products (e.g., CEAT, CIAT) confirmed by ecotoxicity assessments. The mineralization efficiency (Vis-Photo+Fenton-like) reached 83.1 %, significantly higher than that of standalone processes (Fenton-like: 43.2 %; photocatalysis: 30.5 %). The catalyst demonstrated excellent stability (nearly 90 % recovery, < 1 μg/L Co leaching) and practical applicability. This study provides an efficient, sludge-free, and solar-compatible strategy for eliminating persistent herbicides in water treatment.