Microstructural and electrochemical analysis of Sb2O5 doped-Ti/RuO2-ZrO2 to yield active chlorine species for ciprofloxacin degradation

Abstract

ABSTRACT: A Sb2O5 doped-Ti/RuO2-ZrO2 (Ti/SbRuZr) electrode is used to perform the abatement of ciprofloxacin (CIP, C17H18FN3O3). The catalyst was prepared using the Pechini method, and subsequently characterized by XRD, SEM-EDS, EIS and CV. The microstructural analysis of Ti/SbRuZr shows the formation of RuO2 (P42/mnm) and ZrO2 (P2/m) crystalline phases, with an average crystallite size about twice (61.2 nm) lower than Ti/RuO2 (109 nm). Additionally, SEM micrographs reveal that ZrO2 affects the morphological features of the deposited RuO2 layer, turning it into a more heterogeneous material. The electrode capacity was evaluated through the elimination of antibiotic activity (AA) of CIP, revealing that 83 and 45% of AA was removed using Ti/SbRuZr and Ti/RuO2, respectively at 0.19 A h L−1. According to CV analysis, the electrochemical mechanism for CIP degradation was found to proceed through active chlorine species (Cl2-active) on Ti/SbRuZr. This facile kinetics occurring on the ternary catalyst resulted from a high charge transfer resistance for oxygen evolution reaction, as revealed by EIS analysis. HPLC, HPLC-MS, and density functional theory were employed to propose a reaction pathway for CIP degradation. Findings from this work stands out prospective applications of anodic electrochemical oxidation to efficiently eliminate CIP, and the associated proliferation of antibiotic resistant microorganisms in aqueous media.