Oxidative Degradation Kinetics of Recalcitrant Macro and Micropollutants Using CaMFeO3 (M = Cu, Mo, Co) Perovskite Catalyst

Understanding the kinetics behavior of recalcitrant organic degradation in presence of catalyst is important in determining the reaction rates of catalysis. Therefore, this study investigates the kinetic behavior of oxidative degradation for different types of recalcitrant organic pollutants, namely as acid orange II (AOII) macropollutant and caffeine (CAF) micropollutant using B-site substituted CaMFeO3 (M = Cu, Mo, Co) perovskite catalysts. The kinetic study was analyzed based on four kinetic models which are pseudo-zero-order, first-order, second-order and BMG. Interestingly, CaCuFeO3 exhibited a unique kinetic behavior in which the reaction followed a different kinetic model: pseudo-second-order for AOII and pseudo-first-order for CAF. The reaction rate of CAF degradation in the presence of CaCuFeO3 was increased by nine orders of magnitude (k = 1.8×10-3 min-1) within 4 hr of reaction compared to pristine CaFeO3 (k = 0.2×10-3 min-1). On the contrary, CaFeO3, CaMoFeO3 and CaCoFeO3 were fitted to BMG kinetic model for the CAF degradation. These results indicate that the partial substitution of B-site cation in the perovskite structure alters the catalytic reactivity of the resultant substituted perovskite catalysts and subsequently influences the overall kinetics behavior of the oxidative degradation in both recalcitrant macro and micropollutants.