Rapid Degradation of Malathion By Solar Photo-Electro Fenton Process Using an Oxygen Diffusion Cathode

Malathion is a well-known organophosphate pesticide that is still used in Mexico and in other countries of Latin America in attempts to control several insect plagues. It is applied in citrus crops and urban zones. Due to its extended use, Malathion can become a water pollution problem.

In this work, results of degradation and mineralization of Malathion by Solar Photo electro-Fenton using an oxygen diffusion cathode are described. Previously, a factorial experimental design 3² with three repetitions in the central point and desirability function approach were applied to investigate de H₂O₂ production in the oxygen diffusion cathode. The effect of current density and support electrolyte were selected as factors, while produced H₂O₂ concentration and current efficiency were considered as response functions. From the statistical design prediction, the optimum condition for H₂O₂ production were 1 A of current density using 1 M Na₂SO₄ as electrolyte support generating up to 36 mM H₂O₂. Under these conditions, Solar Photo electro-Fenton process was applied for 10 and 30 mg/L Malathion solutions. The degradation by anodic oxidation and electro-Fenton were also compared. The process was more efficient for the lower initial concentration of the pollutant. The results showed that the mineralization of Malathion by solar photoelectro-Fenton process and the photo electro-Fentonprocess for 10 mg/L Malathion were 100% and 80%, respectively, after 240 min of reaction.