Insight into BDD electrochemical oxidation of florfenicol in water: Kinetics, reaction mechanism, and toxicity

Antibiotics in the environment provoke serious consequences on living beings and can be effectively remediated by prominent advanced oxidation process . In this study, electrochemical advanced oxidation treatment in a lab-scale reactor for the degradation of florfenicol (FLO) was studied with the aid of boron-doped diamond anode (BDD). The results exhibited that the FLO degradation follows pseudo-first-order kinetics. As the current intensity rose from 60 mA to 250 mA, the FLO removal efficiency increased and the corresponding reaction rate constant increased from 0.0213 to 0.0343 min −1 , which was likely due to the more efficient participation of free hydroxyl radical ( • OH) generated at the BDD anode. Faster degradation and higher mineralization of electrolyzed FLO solution were achieved at higher current intensity as well as in higher SO 4 2− concentration medium, as a consequence of catalytic participation of oxidants (free • OH as well as sulfate radical (SO 4 •− ) and persulfate (S 2 O 8 2− )). The increase in FLO concentration from 30 to 50 mg L −1 resulted in a reaction rate constant decrease (from 0.0235 to 0.0178 min −1 ). Eight transformation by-products ( m/z  = 372.99, 359.8, 338.0, 324.04, 199.00, 185.02, 168.99 and 78.989) and three inorganic ions (NO 3 − , Cl − and F − ) were analyzed by UPLC‒Q‒TOF‒MS/MS and Ion‒chromatography, respectively. The Vibrio fischeri bioluminescence inhibition revealed an increase of toxicity during the electrochemical oxidation that could be attributed mostly to the generated organic chlorinated by-products ( m / z  = 372.99, 359.8) and inorganic species (ClO 2 − and ClO 3 − ).