FeCeOx catalyzed ultrasonic degradation of diclofenac: Influencing factors, kinetics, and mechanism

This paper studied the removal of diclofenac in FeCeOx catalyzed ultrasonic system. The effects of initial pH, temperature, ultrasonic density and FeCeOx dosage were investigated. Under optimum conditions (pH of 6, temperature of 298 K, ultrasonic density of 2.4 W/cm(3), and FeCeOx dosage of 0.7 g/L), more than 80% removal of diclofenac was achieved within 10 min. The kinetic of FeCeOx catalyzed ultrasonic process fitted Behnajady model very well and the reaction rate constant achieved 0.595 min(-1). The dechlorination efficiency was more than 70% and the kinetic of dechlorination followed pseudo-second order model. The reaction mechanism was proposed based on the existence of surface cerium and iron and the abundant oxygen vacancies in the FeCeOx catalyst. Ce(III) and Fe(III) could accept the electrons transferred by oxygen vacancy and the generated O-1(2) could attack diclofenac molecules, resulting in their mineralization to inorganic products.