Degradation of dye wastewater with a photoelectric integration process (MPEC): Microbial fuel cells-assisted dual electrodes thin-film photoelectrocatalytic.

A novel photoelectric integration process (MPEC) was developed to degrade Amaranth. In the MPEC, the output voltage of the microbial fuel cells (MFCs) was used to assist the dual slant-placed electrodes thin-film photocatalytic (PC). With two MFCs connected in series, the MPEC process realized the highest decolorization efficiency. It is close to that of the external bias photoelectrocatalytic (PEC), and 7% higher than that of the self-generated electric field-assisted photoelectrocatalytic (SPEC). The feasibility of MPEC pre-treatment and MFC post-treatment of Amaranth was investigated. The results demonstrated that MPEC pre-treatment of Amaranth could improve its biodegradability. The higher MPEC decolorization efficiency indicated the stronger biodegradability of the obtained intermediates and the higher MFC output voltage. When the MPEC decolorization efficiency was gradually increased to 50%, the removal efficiencies of total Chemical Oxygen Demand (COD) by the MPEC and MFC increased; when the decolorization efficiency was increased above 50%, the removal efficiencies became stable. MPEC enhanced the biodegradability efficiently and was applicable to pre-treat textile wastewater.

Dual electrodes degradation of Amaranth using a thin-film photocatalytic reactor with dual slant-placed electrodes.

A dual slant-placed electrodes thin-film photocatalytic (PC) reactor was proposed and successfully applied to degrade Amaranth. In this PC reactor, both the TiO2/Ti photoanode and the Cu cathode are slant-placed in the reaction chamber, and aqueous thin-film formed on the surface of both electrodes as wastewater flowed over them. The degradation efficiency was significantly improved as a result of additional degradation at the cathode. When the TiO2 photocatalyst was irradiated with UV light, photogenerated electrons were spontaneously transferred from the anode to the cathode, driven by the electric field self-generated between the TiO2/Ti anode and the Cu cathode, based on the principle of establishing a Schottky barrier. On the Cu cathode surface, the transferred photoelectrons either reacted with dissolved oxygen to form H2O2, which then oxidized the dye, resulting in indirect oxidation decolourization, or reacted with the dye, resulting in direct reduction decolourization. The colour removal efficiency of the cathode was about half that of the photoanode. These processes together with direct oxidation of the photogenerated holes on the photoanode gave dual electrode degradation of the dye, and the degradation efficiency was significantly improved.

Enhanced dye wastewater degradation efficiency using a flowing aqueous film photoelectrocatalytic reactor.

A TiO(2)/Ti flowing aqueous film photoelectrocatalytic (PEC) reactor was developed and successfully applied to degrade Reactive Brilliant Blue X-BR (RBB) and textile effluent. The high treatment efficiency achieved by flowing aqueous film PEC process was attributed to the enhanced light utilization resulting from the significantly reduced path length (down to average approximately 78 micro m level). The dye wastewater was kept circulating (7.7 L h(-1)) during the experiments to continuously refresh the aqueous film on the TiO(2)/Ti photoanode and promote the mass transfer of the target pollutants and the degradation products in the bulk solution. Using a 20-150 mg L(-1)RBB solution as the model system, flowing aqueous film PEC removed color by 83-44% in one hour, much higher than the 75-12% by conventional PEC. Results also suggested that flowing aqueous film PEC was particularly superior to conventional PEC for treatment of a high concentration solution. The feasibility of the TiO(2)/Ti flowing aqueous film PEC reactor was investigated by treating industrial textile effluent. A color and total organic carbon (TOC) removal of 75% and 50% respectively, were achieved in two hours. Thus, in the present study, we propose a new concept for the design of a PEC reactor applicable to industrial wastewater treatment.

Electrochemical-assisted photodegradation of Allura Red and textile effluent using a half-exposed rotating TiO(2)/Ti disc electrode.

In this work, a rotating photoelectrocatalytic (RPEC) reactor, using a half-exposed and half-immersed TiO(2)/Ti disc as photoanode was developed for the first time to degrade Allura Red (AR) and textile effluent. The TiO(2) film was characterised by X-ray reflection diffraction (XRD) spectra and field emission scanning electron microscope (FESEM). When AR solutions with concentrations ranging from 10 mg L(- 1) to 50 mg L(- 1)AR were treated by half-exposed disc PEC (EPEC) process for 1 hour, solution color and TOC were reduced by 36-54% and 19-33%, respectively, higher than reduction of 9-46% and 4-27% observed for the conventional PEC (CPEC) process with half TiO(2)/Ti disc immersed in solution. Similarly, solution color and TOC for textile effluent was reduced by 46% and 10% for EPEC process, respectively, higher than reduction of 26% and 2% for CPEC process. Effectiveness of the RPEC process was further demonstrated in the treatment of textile effluent and textile effluent containing 30 mgL(- 1) AR by determining change of solution color, total organic carbon (TOC), biochemical oxygen demand (BOD(5)), and chemical oxygen demand (COD). Furthermore, a long run experiment was carried out for the TiO(2)/Ti disc and almost stable photoactivity was found after 10 runs of RPEC oxidation of both AR and textile effluent. Our results indicate the proposed RPEC is effective in degrading textile wastewater, probably because the light can directly irradiate the exposed disc in air instead of through solution in the CPEC reactor.