Highly efficient degradation of oxytetracycline in water by the electric assisted micro-electrolysis

• The feasibility of EAME technology to deal with antibiotics was explored. • The EAME for the degradation of OTC was more in line with first-order kinetics. • The degradation rate of OTC in the cathode zone could reach 99.99 % within 30 min. • The evolution pathway of OTC degradation products was deduced under the EAME. Electric assisted micro-electrolysis (EAME), which combines iron–carbon fillings with graphite electrodes, was investigated for the degradation of oxytetracycline (OTC) in simulated wastewater. The study investigated the effects of voltage ranging from 1.0 V to 3.0 V and electrode zones (i.e., anode zone, intermediate zone, and cathode zone) on the removal efficiency of OTC. The reaction pathway was elucidated by FT-IR, LC-MS, and quantum chemical calculations using Gaussian 09 W software. OTC removal proceeded rapidly within the first 30 min, with the cathode zone achieving the highest degradation rate, reaching approximately 99% removal efficiency after 30 min of electrolysis. Kinetic analysis indicated that degradation in the cathode region conformed to a first-order kinetic model, with the rate constant increasing from 0.0748 at 1.0 V to 0.3606 at 3.0 V, representing an increase of approximately 4.82 times. The proposed degradation mechanism of OTC was an electrochemical reduction process, which consisted of demethylation (-CH 2 ), dehydroxylation (-OH), decarbonylation (- C = O ), addition of hydrogen, deamination (-NH 2 ) and so on. Most of the intermediate products were fragmented ions, and finally fragment ions with m/z of 283.1 generated. Combination of experimental and theoretical methods provides technical and theoretical support for the degradation of oxytetracycline in the EAME system, highlights the excellent performance of the cathode region, and provides guidance for process optimization.