Removal Of Antibiotic Contaminants From Aqueous Environment By TiO₂-based Photoanode Materials

With the accelerating pace of urbanization and industrialization,it will bring a certain pollution crisis to water resources,especially the antibiotic-like pollutants in the water environment cannot be removed efficiently.Ciprofloxacin is a typical broad-spectrum antibiotic,a synthetic third-generation fluoroquinolone antibiotic,and its long-term exposure to the water environment can endanger human health.However,traditional wastewater treatment methods cannot remove antibiotic pollutants efficiently and cannot recover the chemical energy from them.The photocatalytic fuel cell is a green technology for wastewater resource and energy generation,which outputs electrical energy while degrading organic pollutants.The selection of photoanode material is the key to the whole photocatalytic fuel cell.Low-cost,stable and non-toxic TiO₂ is the first photocatalytic material to be used as photoanode,but its low utilization of sunlight,rapid compounding of photogenerated electron-hole pairs and mostly good performance in powder form greatly limit its potential application to photocatalytic fuel cells.In this regard,the TiO₂-based photoanode material on Ni foam substrate is used to promote the separation of photogenerated electron-hole pairs by constructing heterojunctions with suitable semiconductors to enhance the efficiency of the photocatalytic fuel cell system.TiO₂ nanoparticles were prepared on Ni foam substrate by hydrothermal and high-temperature calcination using tetrabutyl titanate as precursor,and the optimal dosage was confirmed to be 20 m L.The outstanding electrical conductivity of Ni foam effectively accelerates the separation rate of photogenerated carriers.It possesses good photovoltaic performance through a series of characterization tests and analyzed to degrade 85%of ciprofloxacin in the PFC system within 3 h.The high removal rate was maintained after five cycles of experiments.From the viewpoint of synthesis,the TiO₂/Bi₂O₃ composite with Z-type heterogeneous structure was prepared as the photoanode by introducing the metal semiconductor Bi₂O₃ with suitable band gap,which reduced the forbidden band width and had better photoresponse capability.The short-circuit current density and maximum output power density were 3.227m A/cm² and 0.608 m W/cm²,respectively.The working principle of the photocatalytic fuel cell was analyzed by radical capture and electron spin paramagnetic resonance tests.The g-C₃N₄ was compounded into TiO₂/Bi₂O₃ using hydrothermal method to construct ternary composite photoanode materials,forming a staggered energy band structure to further enhance the photoelectric performance,expand the visible light response range,and further enhance the efficiency of photocatalytic fuel cells to remove 98%of ciprofloxacin within 90min.The formation of multiple heterojunctions suppressed the compounding rate of photogenerated carriers and further promoted the separation of photogenerated electron-hole pairs.The possible degradation pathways of ciprofloxacin were analyzed by LC-MS to provide some reference for the removal of ciprofloxacin in aqueous environment and simultaneous electricity production.