Optimization of Operating Conditions for Electrochemical Decolorization of Methylene Blue with Ti/α-PbO2/β-PbO2 Composite Electrode

Abstract

α-PbO2 was introduced into the intermediate layer of an electrode to prevent the separation of the electrodeposited layer and maintain oxidizing power. The resulting Ti/α-PbO2/β-PbO2 composite electrode was applied to the electrochemical decolorization of methylene blue (MB) and the operating conditions for MB decolorization with the Ti/α-PbO2/β-PbO2 electrode were optimized. The morphology, structure, composition, and electrochemical performance of Ti/α-PbO2 and Ti/α-PbO2/β-PbO2 anode were evaluated using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The optimum operating parameters for the electrochemical decolorization of MB at Ti/α-PbO2/β-PbO2 composites were as follows: Na2SO4 electrolyte 0.05 g L−1, initial concentration of MB 9 mg L−1, cell voltage 20 V, current density 0.05–0.10 A cm−2, and pH 6.0. MB dye could be completely decolorized with Ti/α-PbO2/β-PbO2 for the treatment time of less than one hour, and the dye decolorization efficiency with Ti/α-PbO2/β-PbO2 was about 5 times better, compared with those obtained with Ti/α-PbO2.

Water decontamination under high salinity using the TiO2 NT/PbO2–Cu electrochemical oxidation system: kinetics mechanism and DFT studies

“…1d show two apparent fitting peaks (red and blue curve) corresponding to the O1s region in α-PbO 2 and β-PbO 2 , respectively, according to a previous report, which, indicates the formation of a mixed α-PbO 2 and β-PbO 2 layers. 31…”

“…S1d † exhibit a regular crystallized structure of a pyramidal shape, which, corresponds to β-PbO 2 . 31,32 XPS spectra of Ti 2p and O 1s core levels of the TDNTs substrate are illustrated in Fig. 1a and c.…”

“…1d show two apparent fitting peaks (red and blue curve) corresponding to the O1s region in α-PbO 2 and β-PbO 2 , respectively, according to a previous report, which, indicates the formation of a mixed α-PbO 2 and β-PbO 2 layers. 31 Generally, β-PbO 2 is believed to have better conductivity than α-PbO 2 , whereas the latter has better structural strength. Therefore, if there existed α-PbO 2 in the pure β-PbO 2 layer, the bonding force between the coated layer and electrode surface is supposed to be stronger, which would improve the service life of the electrode to a certain extent.…”