Photocatalytic degradation of atrazine using TiO2 superficially modified with metallic nanoparticles

• Photocatalytic degradation of atrazine performed by metallic NPs supported on TiO2.
• Superficial modification with metallic NPs increased the photocatalytic activity.
• The most active catalyst is Au/TiO2, followed by Cu/TiO2 and Ni/TiO2.
• Only Au is able to maintain its metallic state during the reaction.

The effect of superficial modification of Degussa-P25 TiO2 with different metallic nanoparticles (Au, Cu and Ni) as co-catalysts for the photocatalytic degradation and mineralization of the herbicide atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) was studied. The effect of the oxidation state of the different metals during the reaction was studied. It was observed that whereas the Au particles retain their metallic state, the particles of copper and nickel, which were initially in the metallic state, are oxidized during the reaction, which is detrimental for their photoactivity. It was observed that whereas the bare TiO2-P25 achieved a mineralization of 48% of the initial organic compound after 300 min under reaction conditions, the superficially modified TiO2 with gold nanoparticles (the most active catalyst) achieved a mineralization greater than 60% in the same reaction time and reaction conditions. The evaluation of the activity of these photocatalysts was performed in the presence of UV light (λ = 254 nm) using a low-power lamp (2 W) in solutions of initial concentration of 25 ppm of atrazine.

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