Photocatalytic degradation of atrazine by heteropolyoxotungstates

Abstract

An elegant and eco-friendly photocatalytic degradation approach for the most commonly used herbicide, Atrazine (ATZ); allowed a selective and partial degradation into atrazine-2-hydroxy (Hydroxyatrazine, HAT), which was the sole obtained metabolite. The effect of tungstosilicates and tungstophosphates as photocatalysts under 60 min UV irradiation at two different wavelengths; 254 and 366 nm; was investigated by measuring the absorbance at 10-min intervals, using 720-UV spectrophotometry. ATZ conversion rate was the highest when irradiating with the higher-energy 254 nm UV light. This resulted into 54% degradation in the presence of the silicon-based α-Keggin dodecatungstosilicate [α-SiW12O40]4−, whereas 17% was decomposed in its absence. The nature of the heteroatom as well as the structural type of the studied polyoxometalates had a significant effect on the degradation percentage. Accordingly, 31% of ATZ was only decomposed in presence of the phosphorus-analogue [α-PW12O40]4− whereas the cyclic super-lacunary octatetracontatungstooctaphosphate [P8W48O184]40− increased the degradation to 41%.

Keywords

• polyoxometalates
• photocatalysts
• degradation
• herbicides
• atrazine
• metabolites