Solar photocatalytic mineralization of commercial pesticides: Methamidophos

Aqueous solutions of methamidophos (O,S-dimethyl phosphoramidothioato) are mineralised in sunlight in the presence of dispersed particles of TiO2 in a pre-industrial pilot plant. A commercial pesticide (Tamaron 50®, 50% Methamidophos) is used as a model to demonstrate the application of the treatment. Total Organic Carbon (TOC) and PO43− are analysed to confirm the mineralization of the contaminants. The concentration of organics in water was set at TOC ≈ 100 mg/L, but with only illuminated TiO2, mineralization was slow. Oxidation of the organics present in the formulation is enhanced 18 times by use of an appropriate electron scavenger (peroxydisulphate) compared to TiO2 alone.