Photo Catalytic Degradation of Chlorpyriphos in an Annular Slurry Reactor

K. Sivagami, R. Ravi Krishna, T. Swaminathan




Increasing use of pesticides is causing severe environmental impacts due to their toxicity and health effects. An effective treatment technique for their removal from wastewaters is necessary. The photo catalytic degradation of Chlorpyriphos, an Organo Phosphate Pesticide, using TiO2 was investigated in suspended system under UV irradiation. Batch degradation experiments were carried out at initial concentrations ranging from 5 to 50 mg/L at a pH ranging from 3.5 – 10.5 and at a catalyst loading of 0.5 – 2 g/L. The studies on batch photo catalytic degradation of chlorpyriphos, showed about 80 – 99% degradation depending on the initial pesticide concentration, pH and the amount of catalyst. pH had a noticeable effect on removal efficiency in degradation. High removal efficiency obtained in 5 – 50 mg/L indicated effectiveness of this process and its potential for practical application. The photocatalytic oxidation of Chlorpyrifos over illuminated TiO2 fitted well with Langmuir-Hinshelwood (L-H) kinetics model. The values of the adsorption equilibrium constant, Kpesticide, and the rate constant, kL-H were 0.0218 L/mg and 65.78 mg/L. min, respectively.


Keywords: Photo catalysis; TiO2; annular reactor; chlorpyriphos; L-H kinetics; UV irradiation