Electrochemical-assisted photodegradation of Allura Red and textile effluent using a half-exposed rotating TiO₂/Ti disc electrode

Abstract

In this work, a rotating photoelectrocatalytic (RPEC) reactor, using a half-exposed and half-immersed TiO₂/Ti disc as photoanode was developed for the first time to degrade Allura Red (AR) and textile effluent. The TiO₂ 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 TiO₂/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 (BOD₅), and chemical oxygen demand (COD). Furthermore, a long run experiment was carried out for the TiO₂/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.

Keywords:

• TiO₂/Ti disc electrode
• photoelectrocatalytic degradation
• Allura Red
• textile effluent
• UV light

Acknowledgments

Financial support from the Natural Science Foundation of China (Project No. 20477026) is gratefully acknowledged.