Electrochemical detoxification of tetrabromobisphenol A-contaminated water using Ti/SnO2-Sb/PbO2-Ce anodic membrane

Abstract

Degradation of refractory organics has been limited by their low mass-transport rates in conventional flow-by operated electrochemical reactors. This study explores for the first time the development of porous titanium (Ti)-based metal oxide anodic membrane for efficient flow-through degradation of recalcitrant tetrabromobisphenol A (TBBPA). For this purpose, a duplexed Ti/SnO2-Sb/PbO2-Ce anodic membrane was successfully prepared by sol-gel and electrodeposition methods. Ti/SnO2-Sb/PbO2-Ce exhibited improved mechanical and electrochemical stability, larger electrochemical surface area, higher oxygen evolution potential and lower charge transfer resistance, as compared to its mono-layered rival (Ti/SnO2-Sb). The switching from flow-by to flow-through operation resulted in an increased mass transfer rate constant and narrowed diffusion layer thickness of Ti/SnO2-Sb/PbO2-Ce. In the flow-through mode, Ti/SnO2-Sb/PbO2-Ce enabled the complete TBBPA removal at a relatively low electric energy (0.11 kWh m−3). The TBBPA removal was ascribed to the direct anodic oxidation and indirect anodic oxidation incurred by absorbed HO, free HO and 1O2. The intermediate products, which were arisen from the attack of TBBPA by these reactive species, were identified. We further estimated their acute toxicities and bioaccumulation factors. This research proposed a robust electrochemical filtration approach for detoxification of TBBPA-contaminated water.