Heterogeneous catalytic oxidation of ciprofloxacin over CuFe/Al₂O₃: Multi-variable optimization by Box Behnken design and kinetic interpretation

Ciprofloxacin (CIP), as a commonly used fluoroquinolone antibiotic, is frequently detected in pharmaceutical effluents and aquatic environments and poses significant microbiological hazards due to low biodegradability and high stability. In this study, heterogeneous catalytic oxidation of ciprofloxacin was explored using a bimetallic CuFe/Al₂O₃ catalyst synthesized by wet impregnation method. FTIR, XRD, SEM, and BET analyses characterized the catalyst, showing Cu and Fe oxides uniformly distributed on the Al₂O₃ support and a mesoporous structure with a specific surface area of ۹۱.۹ m² g⁻¹. Subsequently, batch oxidization experiments determined the influence of operating parameters (catalyst dosage, initial pH and reaction time) on ciprofloxacin removal efficiency. Box–Behnken Design (BBD)of Response Surface Methodology (RSM) verified process optimum and variable interaction analysis. Maximum CIP degradation of ۸۰.۶۶ % was observed in aqueous solution at optimal operating conditions. Kinetic studies showed pseudo-first-order kinetics (k = ۰.۰۱۹۱ min⁻¹ (R² = ۰.۹۹۱۱); t₁/₂ = ۳۶.۳ min) confirmed rapid oxidation. CuFe/Al₂O₃ showed superior performance due to the redox cycle of Cu²⁺/Cu⁺ and Fe³⁺/Fe²⁺ species, advantageous generation of hydroxyl radicals from heterogeneous Fenton-like reactions. Therefore, the results support that CuFe/Al₂O₃ catalyst is a worthwhile and stable catalyst for antibiotic breakdown via advanced oxidation for sustainable pharmaceutical wastewater treatment.

کلیدواژه ها:

Pharmaceutical wastewater ، Ciprofloxacin ، CuFe/Al₂O₃ catalyst ، Box–Behnken design (BBD) ، Kinetic interpretation