Electro-Catalytic Oxidation of Ofloxacin Antibiotic in Continuous Reactor: Evaluation, Transformation Products and Pathway

Abstract

Present study investigates the degradation capability of ruthenium oxide coated titanium (Ti/RuO2) anode for ofloxacin (OFLX) antibiotic, using electro-oxidation (EO) technique in a continuous reactor. Further, the degradation mechanism and its pathway were explored with intermediate/final OFLX transformation products identification. The EO method was optimized using response surface methodology (RSM). Effect of process parameters such as applied current (I), initial pH of wastewater, elapsed time (t) and retention time (RT), on % total organic carbon (TOC) removal, %OFLX removal and specific energy consumption (SEC, kWh (g TOC removed)−1) was studied in detail and the EO mechanism was explored. Under optimum conditions, 76.78% OFLX removal and 23.85% TOC removal were achieved with 0.706 kWh (g TOC removed)−1 of SEC. OFLX and TOC removal followed pseudo-first order kinetics with rate constant (kf) values of 5.3 × 10−2 and 1.5 × 10−2 min−1, respectively. UPLC-Q-TOF-MS analysis of samples extracted from reactor at pre-determined time-intervals revealed the presence of seven reaction intermediates formed during continuous EO treatment of OFLX. Subsequently, a plausible degradation pathway of OFLX by EO using Ti/RuO2 anodes was proposed.