Degradation of atrazine in aqueous solution through peroxymonosulfate activated by Co-modified nano-titanium dioxide

Peroxymonosulfate (PMS) heterogeneous activation by Co₃ O₄ -modified catalyst has shown significant implications to generate free radicals for organic pollutants degradation in water. In this study, PMS heterogeneous activation was applied to degrade atrazine (ATZ) using Co₃ O₄ -mediated titanium dioxide nanoparticles (Co₃ O₄ /TiO₂ NPs), which were synthesized by sol-gel method. Firstly, characteristics of the fresh and used Co₃ O₄ /TiO₂ NPs were analyzed via SEM, TEM, XRD, EDS, and XPS techniques. Then, the influences of several key parameters (i.e., Co₃ O₄ /TiO₂ NPs dose (0.02-0.3 g/L), PMS dose (0-0.6 mM), initial pH (3.0-11.0), and co-existing anions) on the ATZ degradation were investigated systematically. Besides, control systems were set up to verify the high efficiency of Co₃ O₄ /TiO₂ NPs. In addition, the radical scavenging experiments revealed that sulfate and hydroxyl radicals were generated in the Co₃ O₄ /TiO₂ -PMS system, while sulfate radicals were the dominant reactive species responsible for ATZ degradation. Furthermore, the stability and reusability of the Co₃ O₄ /TiO₂ NPs were investigated after four consecutive experiments. Based on the identified products, possible degradation pathways of ATZ in the Co₃ O₄ /TiO₂ -PMS system were proposed. Finally, the possible reaction mechanism of Co₃ O₄ /TiO₂ -PMS system was proposed according to the comprehensive analysis. Findings of this study provided useful information for the application of Co₃ O₄ /TiO₂ NPs in recalcitrant organic contaminants degradation. PRACTITIONER POINTS: Co₃ O₄ /TiO₂ NPs were synthesized via the simple sol-gel method. Co₃ O₄ /TiO₂ NPs possessed excellent catalytic performance for PMS to eliminate ATZ. Sulfate radicals play a dominant role in the degradation of ATZ. ATZ degradation pathways and reaction mechanism in the system were proposed.