Facile electrochemical fabrication of GO@ZnO@MnO2 nanocomposite for catalytic ozonation of ciprofloxacin: experimental optimization and machine learning modeling

Abstract

The persistence of ciprofloxacin (CIP), a widely used fluoroquinolone antibiotic, in aquatic environments poses serious risks to ecosystems and human health due to its recalcitrance and contribution to antimicrobial resistance. Herein, a novel graphene oxide-zinc oxide-manganese dioxide (GO@ZnO@MnO₂) nanocomposite was successfully synthesized via a facile, one-step electrochemical exfoliation method and employed as a highly efficient heterogeneous catalyst for the ozonation of CIP. The optimal nanocomposite ratio (60 : 35 : 5) achieved 90.20% total organic carbon (TOC) removal within 50 min under mild conditions (pH 9.0, catalyst dosage 1.0 g L⁻¹, initial TOC 12.21 mg L⁻¹), representing a 2.8-fold enhancement compared with ozonation alone (32.52%). The corresponding pseudo-first-order rate constant for TOC abatement during CIP degradation was 0.0532 min⁻¹, significantly higher than those of the binary and pristine systems. Scavenger experiments indicated that hydroxyl-radical-mediated oxidation contributed significantly to CIP mineralization; however, the limited suppression (∼22% decrease in k) after scavenger addition strongly suggests that surface-mediated oxidation pathways and/or direct ozone reactions also played a substantial role in the overall catalytic ozonation process. Furthermore, four machine-learning models were developed to predict TOC removal efficiency. The artificial neural network (ANN) and support vector machine (SVM) models provided the strongest predictive fit within the available experimental dataset (R² = 0.977 and 0.976, respectively), with reaction time identified as the most influential variable. This study presents the first integration of green electrochemical synthesis, systematic parametric optimization and high-accuracy machine-learning modeling for catalytic ozonation of CIP, offering a sustainable and predictive strategy for the efficient mineralization of recalcitrant antibiotics in wastewater.