Treatment of hazardous organic amine wastewater and simultaneous electricity generation using photocatalytic fuel cell based on TiO2/WO3 photoanode and Cu nanowires cathode

Organic amines are regarded as high toxic, refractory chemicals due to the great damage on human body, and ecosystem. The treatment of organic amine wastewater involves the removal of total nitrogen and toxic organics simultaneously, which is one of the biggest difficulties in wastewater treatment. In this study, hazardous organic amine wastewater was purified by a photocatalytic fuel cell (PFC) with efficient nitrogen removal and organic degradation, and its chemical energy was recovered simultaneously based on hydroxyl radical (HO center dot) and chlorine radical (Cl center dot) reaction in a novel TiO2/WO3 and 3D Cu nanowires modified Cu foam (CuNWs/CF) system. TiO2/WO3 heterojunction as photoanode provided rapid charge separation and good stability, and the composite of poly-Si enhanced the light harvest and charge transfer. HO center dot played critical role in degrading organic amines, while Cl center dot was responsible for selectively oxidizing amine group or NH4+ to N-2. Besides, trace amount of NO2- and NO3- formed by over-oxidation was eliminated on CuNWs/CF cathode due to large specific surface area and fast charge transfer. Moderate Cl- concentration and initial pH had vital influence on strengthening Cl center dot and HO center dot generation in the system, and the optimal conditions were 50 mM NaCl and pH = 7. For methylamine, ethy-lamine and dimethylamine wastewater, the system showed total nitrogen removal efficiency of 94.93%, 91.81%, 93.10% and total organic carbon removal of 58.47%, 53.57%, and 56.71% within 2 h, respectively. Moreover, the corresponding maximum power densities of 2.49, 2.40, 2.27 mW cm(-2) were also generated, respectively. The study proposes an efficient, sustainable method for the treatment of hazardous organic amine wastewater and simultaneous energy recovery.

Automated summary

This study utilized a photocatalytic fuel cell (PFC) to purify hazardous organic amine wastewater, achieving efficient nitrogen removal, organic degradation, and simultaneous energy recovery based on hydroxyl radical (HO center dot) and chlorine radical (Cl center dot) reactions in a TiO2/WO3 and Cu nanowires modified Cu foam system.