Oxidation of fenuron by chlorine dioxide

The oxidation of the herbicide Fenuron in aqueous solutions by chlorine dioxide has been studied in a discontinuous reactor. The effect of the operating variables on the degradation process has been established: while temperature and initial concentration ratio M=[ClO2]o/[Fenuron]o have a positive influence, the pH seems to have no influence. Also, the effects of ultra-violet irradiation, u.v.-oxygen, ozone and u.v.-ozone, on the herbicide destruction were investigated. A stoichiometric ratio of 2 moles of chlorine dioxide consumed per mol of Fenuron reacted is deduced, and a reaction mechanism that justifies this stoichiometry is proposed. Finally, a kinetic study is performed: the experimental results support a second order overall kinetics, and the rate constants are determined, being well correlated by the Arrhenius expression: k = 1.42 × 1011 exp(-6635/T) (L/mol.min)