Catalytic Wet Oxidation of Real Pharmaceutical Wastewater over a Copper-Based Catalyst Under Mild Conditions

Catalytic wet oxidation (CWO) is regarded as a high-efficiency and promising advanced oxidation process for the treatment of high-strength and recalcitrant organic wastewater. Herein, catalytic wet oxidation of real pharmaceutical wastewater over a synthesized CuO/Al2O3 catalyst under mild conditions was investigated. The crystal structure, surface micromorphology, elemental distribution, and chemical valence states of the synthesized catalyst were analyzed. Batch experimental results verified that the chemical oxygen demand (COD) removal efficiency was positively dependent on reaction temperature, retention time, and oxygen supply. The highest COD removal efficiency of 82.6% was achieved under the optimized operating conditions (280 °C, 60 min, catalyst dosage 8.0 g/L, and initial oxygen pressure 1.2 MPa). Box–Behnken design-based response surface methodology (RSM) was utilized to quantitatively explore the interactive coupling effects of key process parameters on COD removal performance. Regression modeling and analysis of variance (ANOVA) results confirmed that the significance of the influence of operational parameters followed the following sequence: reaction temperature > reaction time > oxygen dosage. This study demonstrates that the synthesized copper-based catalyst exhibits excellent catalytic activity and stability under mild hydrothermal conditions, which provides an efficient and promising strategy for the treatment of high-strength pharmaceutical wastewater.