Electrospun YFeO₃ and activated carbon nanofibers as electrodes for photoelectrochemical degradation of Orange II and sulfamethazine

Electrospun perovskite YFeO₃ nanofibers (YFONFs) and activated carbon nanofibers (ACNFs) were developed to treat conventional azo dye Orange II and the emerging pollutant sulfamethazine (SMT). By optimizing the polymer concentration, feed flow rate, tip-to-collector distance, and applied voltage during the electrospinning process, nanofibers with a regular shape, uniform size, distribution, and compactness were obtained. Utilizing the electrospun YFONFs and ACNFs as the anode and cathode, respectively, in an undivided photoelectrochemical system enabled the degradation of target pollutants with high removal efficiency (RE). This is attributed to the synergetic effect of the anodic photoelectrocatalytic oxidation and the cathodic photoelectron–Fenton reactions, which were individually confirmed through a divided photoelectrochemical system. The applied voltages were determined at 20 and 25 V for treating Orange II and SMT, respectively, by considering the RE and energy consumption. In addition, ion concentrations of 7 mM Na₂SO₄ and 0.75 mM FeSO₄, temperatures of 30 °C for Orange II and 35 °C for SMT, and pH 3 were found to be optimal for improving the RE of the target pollutants owing to the promoted photoelectrogeneration of hydroxyl radicals ([rad]OH). It was also found that the degradation kinetics of the target pollutants followed a proposed pseudo-first-order model rather than a pseudo-second-order model, indicating the significance of single-molecule reactions upon pollutant degradation.