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

Abstract

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 (0.02-0.3g/L), PMS dose (0-0.6mM), 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.