| Applying the principle of electro-photocatalysis and microbial fuel cell in waste water treatment, not only pollutants can be degraded and removed, but also electricity can be generated at the same time. Their combination is expected to reduce energy consumption for water pollution control and improve the efficiency. So, the properties of electro-photocatalysis of silver phosphate in pollution control, plus its coupling with microbial fuel cell technology were studied in this paper. Ag3PO4 photocatalyst was prepared by one step precipitation method, then it was dispersed by tetraethyl orthosilicate sol and loaded onto stainless steel mesh, followed by drying, the electrodes were made finally. The photocatalyst powder was characterized by XRD, SEM, TEM, and the loaded catalyst was also characterized by SEM. Photocatalytic activities were studied of the stainless steel mesh based photocatalytic electrode in degradation of model pollutant, rhodamine B, and the removal results of RhB under visible light were measured; The RhB removal and electricity generation from system composed of the photocatalytic cathode and iron anode were studied, it is found that the addition of the supporting electrolyte can significantly improve the performance in degradation and decolorization; Finally constructing a coupled photocatalytic and microbial fuel cell system using carbon rod as anode and the photocatalytic electrode as the cathode, the RhB removal and production of electricity in this system were studied, photocatalytic cathode coupling with MFC improved the performance of degradation of RhB significantly. The results/conclusion are as follows:(1) Ag3PO4 visible light photocatalyst was successfully fabricated using the one step precipitation method. The Characterization from SEM and XRD indicates the catalyst crystal is cubic, TEM image shows the particle size is about 10～50 nm; SEM image shows that the catalyst loading on stainless steel mesh was well dispersed.(2) Using supported photocatalyst, removal rate of RhB reached 61% after reaction 4 h when the initial concentration of RhB is 10 mg/L (100 mL), illuminated by a 100 W tungsten halogen lamp, with catalyst loaded 100% at aeration rate 0.1 m3/h.(3) Photo-electrocatalytic removal of RhB using iron as anode and photocatalytic cathode:RhB removal rate increased from 61% to 65% after 4 h illumination under 100 W tungsten halogen lamp, when the electrolyte is added, the removal rate was raised to 70%. Without a supporting electrolyte, the maximum output voltage and power densities was 9 mV,0.129 mW/m2 respectively, and when NaCl was added in the system, the output voltage and power density increased(23 mV,38.8 mW/m2).(4) Coupling Ag3PO4 photocatalysis with MFC, the removal rate of RhB(200 mL, the initial concentration of 50 mg/L) reached 92% after 4h illumination under 100 W tungsten halogen under optimum conditions; and the maximum output voltage and power density at this time was 124 mV,34.9 mW/m2.(5) The stability of loaded photocatalytic electrode is very good. Its removal rates were 92%,89%,97%,91%,89% when the loaded photocatalytic electrode was reused 5 times; the maximum voltages were 126 mV,154 mV,144 mV,246 mV,139 mV; the maximum output power density were 40.1 mW/m2,49.0 mW/m2,37.5 mW/m2,94.9 mW/m2,41.7 mW/m2.Results from this study about coupling photocatalysis with microbial fuel cell provide important and valuable data, as well as reference information for designing new efficient and energy-saving technology and process combination for treating recalcitrant pollutants. |
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