TiO₂/g-C₃N₄@HPBC Photoanode in PMFC for Shipboard Oily Wastewater Degradation

Abstract

This study addresses the problems of high energy consumption, high cost, and incomplete removal existing in traditional treatment methods for oily wastewater from ships, and proposes and constructs a Photocatalytically-assisted Microbial Fuel Cells (PMFC) device for efficient and green treatment. The device couples photocatalysis with Microbial Fuel Cell (MFC) technology, utilizing ⋅OH and ⋅O₂⁻ generated by semiconductor photocatalysts under illumination to synergistically degrade oil pollutants with microbial metabolism. Specifically, pine cone shell biochar (PBC) modified by high-temperature carbonization (350°C) and H₂O₂ oxidation (HPBC) is used as the anode substrate, which significantly improves its hydrophilicity (contact angle reduced to 44.637°) to facilitate the attachment of photocatalysts and microorganisms. Then, a TiO₂/g-C₃N₄ heterojunction photocatalyst (TiO₂/g-C₃N₄@HPBC) is loaded to construct a composite photoanode. A two-chamber PMFC reactor is built, using an emulsified diesel solution prepared with an inorganic salt medium as the anolyte, a potassium ferricyanide solution as the catholyte, and a composite microbial community as the anode microorganisms. The results show that the maximum output voltage of 0.6389V and oil degradation rate of 76.34% of PMFC under illumination are significantly higher than the maximum output voltage of 0.5832V and oil degradation rate of 71.72% under dark conditions, confirming that the photocatalytic effect effectively improves the power generation performance and pollutant degradation efficiency of the system. The PMFC device provides an energy-saving and efficient potential solution for the treatment of oily wastewater from ships.