Efficient Treatment of Contaminated Water Containing Doxycycline Through Electro-Fenton and Anodic Oxidation Processes: Characterization and Parameters Effect

The removal of pharmaceutical pollutants from the aqueous environment is a significant challenge that human beings are facing. In the current study, electro-Fenton (EF) and Anodic oxidation (AO) processes were applied separately to remove doxycycline (DOX) antibiotic from polluted water. For the EF process, carbon cloth cathode and Pt anode were used, and for the AO process, Ti/RuO₂-IrO₂ anode, and active carbon cathode were used. Raman spectroscopy, X-ray diffraction, atomic force microscopy, scanning electron microscopy, mapping by energy dispersive X-ray spectroscopy, and cyclic voltammetry analyses were done to study the electrodes of the EF and AO processes. The investigated variables in the EF and AO processes for DOX removal were current density (CD, mA/cm²), pH, DOX concentration (mg/L), and reaction time (min). For this purpose, the response surface methodology was applied. According to the results, the highest DOX removal efficiency was achieved at a CD of 16 mA/cm², pH = 3, DOX concentration of 20 mg/L, and reaction time of 120 min for the EF process. The optimal values of the AO process for CD, pH, DOX concentration, and process time were 24 mA/cm², 3, 20 mg/L, and 120 min, respectively. Finally, the amount of DOX mineralization and the intermediates of DOX removal were determined via total organic carbon and gas chromatography–mass spectrometry analyses for both the EF and AO methods.