The presence of organic micro-pollutants (OMPs) in water bodies has become a major hindrance to protecting water quality in recent years. One of the main sources of OMPs is wastewater treatment plant (WWTP) effluents. One of the most recent Advanced Oxidation Processes (AOPs) technology is photo-electrocatalysis (PEC), which can produce radicals to oxide OMPs in an aqueous medium driven by solar energy and an external bias potential. In this study, ultrasonic spray pyrolysis was determined as a proper method to fabricate the ZnO/BiVO4 heterojunction. Then, the prepared photoanodes were characterised by X-ray Photoelectron spectroscopy (XPS), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), UV-vis and Incident Photo-to-electron Conversion Efficiency (IPCE). The results demonstrated the ZnO/BiVO4 heterojunction was successfully fabricated on the Fluorine-Tin-Oxide (FTO) glass. Moreover, the LSV and EIS analysis were carried out in this study to analyse its photo-electrochemical properties. The PEC degradation experiments were carried out in 10 μg/L of 11 OMPs spiked in MiliQ and in real WWTP effluent under simulated solar illumination at 1 V potential bias for three hours. Nine and four of 11 OMPs had achieved more than 70 % degradation efficiency when ZnO/BiVO4 photoanode was conducted to degrade spiked MiliQ and spiked real WWTP effluent. Except for diclofenac and sotalol, the real effluent showed inhibition to the degradation efficiencies and kinetic coefficient of the other nine OMPs. The concentrations of TOC, COD and NO3-N increased after the PEC process. The increase was found to be related to the disintegration of the carbon stick cathode. To further enhance the PEC process, the ZnO@GD/BiVO4 photoanode and adding persulfate were conducted the PEC degradation experiments separately in spiked real WWTPs effluent. Both two approaches showed an enhancement of the PEC process and improved degradation efficiencies. The results obtained in the present work reveal that the PEC process has excellent potential for the removal of OMPs from WWTPs effluent.

Currently, organic micropollutants (OMPs) are continuously and uncontrollably released into the water environment worldwide, as the reason for their special properties, OMPs removal has been a global challenge. This study focuses on acetaminophen degradation by photo-electrolysis (PEC) activities, which is one of the promising advanced oxidation processes (AOP) technologies. First, we report the fabrication methods of the BiVO4/BiOI heterojunction on FTO glass, then characterised the prepared photoanodes with XPS, XRD, SEM, EDS, UV-vis and IPCE. The results demonstrated the BiVO4/BiOI p-n heterojunction had been successfully electrodeposited on the FTO glass. Further, the LSV and EIS analysis in this study showed the BiVO4/BiOI photoanode had less photocurrent density than BiVO4 when carried out in the solution of acetaminophen. Even if the heterojunction did not improve the photocurrent, it significantly enhance the acetaminophen removal efficiency in the PEC degradation process. BiVO4/BiOI photoanode achieved 99% degradation efficiency in 3 hours and obtained 0.019 mi n−1 of the reaction rate constant. Overall, these results indicate that BiVO4/BiOI heterojunction has a great application potential for the degradation of OMPs in the wastewater treatment plants secondary effluent.

The presence of organic micro-pollutants (OMPs) in wastewater treatment effluents is becoming a major threat to the water safety for aquatic and human health. Photo-electrocatalytic based advanced oxidation process (AOP) is one of the emerging and effective techniques to degrade OMPs through oxidative mechanism. This study investigated the application of heterojunction based BiVO4/BiOI photoanode for acetaminophen (40 μg L−1) removal in demineralized water. Photoanodes were fabricated by electrodeposition of BiVO4 and BiOI photocatalytic layers. Optical (UV–vis diffusive reflectance spectroscopy), structural (XRD, SEM, EDX) and opto-electronic (IPCE) characterization confirmed the successful formation of heterojunction for enhanced charge separation efficiency. The heterojunction photoanode showed incident photon to current conversion efficiency of 16% (λmax = 390 nm) at an external voltage of 1 V under AM 1.5 standard illumination. The application of the BiVO4/BiOI photoanode in the removal of acetaminophen at 1 V (external bias) vs Ag/AgCl under simulated sunlight showed 87% removal efficiency within the first 120 min compared to 66% removal efficiency of the BiVO4 photoanode. Similarly, combining BiVO4 and BiOI exhibited 57% increase in first order removal rate coefficient compared to BiVO4. The photoanodes also showed moderate stability and reusability by showing 26% decrease in overall degradation efficiency after three cycles of each 5 h experiment. The results obtained in this study can be considered as a stepping stone towards the effective removal of acetaminophen as an OMP present in wastewater.@en