Oxidative degradation of AOII dye by bicarbonate-activated hydrogen peroxide in the presence of CaCu0.5Fe0.5O3 perovskite: influence of initial pH

The catalytic performance of Acid Orange II (AOII) degradation by bicarbonate-activated hydrogen peroxide in the presence of CaCu0.5Fe0.5O3, and the influence of initial pH during the reaction, were investigated in this study. The introduction of bicarbonate (NaHCO₃) into the CaCu0.5Fe0.5O3/H2O2 system significantly enhanced AOII degradation, achieving 94% removal within 5 minutes of reaction, which was 2.5 times higher than that observed in the absence of NaHCO₃ (38%). The BAP-CaCu0.5Fe0.5O3 system effectively degraded AOII across a wide pH range, following a pseudo-second-order kinetic model. Notably, the rate constant at an unadjusted initial pH of 6.4 (k = 0.0949 Lꞏmg⁻¹ꞏmin⁻¹) was approximately 1.7 times higher than that at pH 8 (k = 0.0549 Lꞏmg⁻¹ꞏmin⁻¹), although both conditions achieved comparable AOII degradation efficiencies (>98%) after 30 minutes of reaction. The BAP–CaCu0.5Fe0.5O3 system exhibited its most efficient catalytic performance and fastest AOII degradation rate at an unadjusted initial pH of 6.4, highlighting the critical influence of near-neutral pH on reactive species generation. These findings provide new insights into the role of bicarbonate and initial pH in enhancing the oxidative degradation of organic pollutants using CaCu0.5Fe0.5O3 perovskite catalysts within the bicarbonate-activated hydrogen peroxide system.