Solar photocatalytic mineralization of commercial pesticides: Oxamyl

One of the most important sources of high-pesticide-content polluted waters results from the rinsing of pesticide containers. In this paper, a pre-industrial solar TiO2-photocatalytic treatment is used to prevent such pollution of continental waters and a commercial pesticide (Vydate L®, 24% oxamyl) is used as a model to demonstrate the practical application of the treatment. A method for comparing photocatalytic solar reactor efficiency based on solar UV measurement is proposed. Total organic carbon (TOC) analysis is applied to confirm the total mineralization of the contaminants. When photocatalytic treatment is begun, the concentration of organics in water is TOC≃100 mg l−1. Oxamyl is completely photodegraded, but mineralization is slow with illuminated TiO2 only. The additional use of an adequate electron scavenger (peroxydisulphate) clearly enhances oxidation of the pesticide, its intermediates and the other organics present in the commercial formulation to CO2.