Ultra-fast detoxification of Sb(III) using a flow-through TiO2-nanotubes-array-mesh based photoelectrochemical system

Herein, we designed a flow-through photoelectrochemical system consisting of a TiO2-nanotubes-array-mesh filter to achieve ultra-fast detoxification of highly toxic Sb(III). Upon application of UV-LED irradiation and an electrical field, in situ conversion of Sb(III) to less toxic Sb(V) can be achieved with a single-pass through the filter (tau < 2 sec). We identified an evident synergistic effect between electrochemical and photocatalytic processes. The detoxification efficiency enhanced with an increase in applied voltage from 22.6% (at 0 V) to 96.7% (at 1.5 V). This could be the combined advantages of filter's flow-through design, photoelectrochemical activity of the filter, and decreased charge recombination rate. The EPR analysis proved that hydroxyl radical dominated the process of Sb(III) conversion. At 1.5 V, 800 mu g/L Sb(III)-spiked tap water still maintained an > 95.6% Sb(III) oxidation efficiency. Overall, this study established a novel, effective, and promising photoelectrochemical system to accomplish the second-level detoxification of highly toxic Sb(III).