Photocatalytic oxidation and catalytic wet air oxidation of real pharmaceutical wastewater in the presence of Fe and LaFeO3 doped activated carbon catalysts

Abstract

Real pharmaceutical wastewater was treated by photocatalytic oxidation and catalytic wet air oxidation (CWAO) processes. The catalytic performance of Fe/AC and LaFeO3/AC (AC: Commercial activated carbon) was compared in the advanced oxidation processes. The influences of the reaction parameters were determined by using Box–Behnken design. Fe/AC catalyst was more effective in both of the photocatalytic oxidation and catalytic wet air oxidation processes. In the photocatalytic oxidation process, 72.7% COD removal was achieved at pH = 4.5, 2.0 g/L, and [H2O2]o = 0.32 mM. Under the optimum conditions of the CWAO, which were determined as 3 g/L of catalyst loading, pH = 3, and 50℃, 83.1% COD removal efficiency was obtained. CWAO method was determined as more suitable since a higher COD removal efficiency was achieved in a shorter reaction time. The toxicity in terms of L. sativum growth inhibition was evaluated as 4.82% after the CWAO treatment. A two-step first-order reaction kinetics provided the best fit of the CWAO experimental data. The activation energies of the fast and the slow steps were 25,661.16 and 28,327.46 J/mole, respectively.