Phototransformation of pesticide in the presence of moroccan natural phosphate in aqueous solution

Natural phosphate is a natural rock formed through geological processes. The use of phosphates is widespread in both industry and agriculture. Moroccan reserves account for around 50% of the world total. The aim of this work is to study the photosensitizer effect of natural phosphate on the degradation of oxamyl under polychromatic light. Oxamyl is not amenable to direct photolysis. Indeed the UV-Visible spectrum of oxamyl shows no absorbance at these wave radiations. We have also verified that there was no reaction in the mixture oxamyl - natural phosphate in the dark and thermostatically controlled temperature of 25 °C. The irradiation of oxamyl in the presence of natural phosphate, leads to its degradation. The photodegradation rates were compared by varying substrate and inducer concentrations. A single photoproduct was found and identified by LC/MS analysis as the derivative of oxime.