Fabrication and electrochemical treatment application of a microstructured TiO2-NTs/Sb–SnO2/PbO2 anode in the degradation of C.I. Reactive Blue 194 (RB 194)

A microstructured Sb-doped SnO2/PbO2 electrode was synthesized and investigated for the treatment of C.I. Reactive Blue 194 (RB 194) in aqueous solution. An electrochemical method was employed for the electrodeposition of PbO2 on an ordered microstructured TiO2-NTs template to obtain a large specific surface area and high space utilization. The TiO2-NTs/Sb–SnO2/PbO2 electrode was characterized by XRD, SEM and cyclic voltammetry and the results showed that the predominant phase of the lead dioxide anode is β-PbO2. The decolorization and mineralization of dye RB 194 was investigated by UV–vis measurements and TOC analysis. The removal efficiency was studied as a function of several operation variables, such as current densities, initial dye concentration, initial pH values and chloride ions. It was found that the TiO2-NTs/Sb–SnO2/PbO2 electrode exhibited good decolorization and mineralization capability of RB 194 in neutral conditions at a current density of 150 mA/cm2, with an initial dye concentration of 30 mg/L. On the basis of the reaction products identified, a possible degradation pathway for the anodic oxidation of non-biodegradable organic dye RB 194 in aqueous solution is proposed.

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► A modified TiO2-NTs/Sb–SnO2/PbO2 electrode was synthesized for RB 194 removal.
► Compared with others, the modified PbO2 electrode has more porous structured surface.
► The electrode achieves the optimal removal efficiency under certain conditions.
► The results indicated that the modified anode had well rapid discoloration ability.
► The intermediate products were gradually oxidized to small organic matters and CO2.