Electrochemically assisted photocatalytic degradation of Acid Orange 7 with β-PbO2 electrodes modified by TiO2

Modification of β-PbO2 electrodes was carried out by TiO2 co-deposition and characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The 2.0 g TiO2 (the amount of TiO2 used in 200 mL electrodeposition solution) modified β-PbO2 electrode was more compact and more uniform in comparison with the unmodified β-PbO2 electrode. TiO2 particles were tightly attached on and between β-PbO2 crystals on modified β-PbO2 electrode. It was also used in electrochemically assisted photocatalytic degradation (EAPD) of Acid Orange 7. Compared with the total efficiency by a single application of ultraviolet irradiation and electrochemical procedure, application of a 1.5 V potential in EAPD improved the apparent first-order rate constant by 44.2% for 2.0 g TiO2 modified β-PbO2 electrode even if it was not freshly used. A synergetic effect was significant. Within the amount of TiO2 investigated, the more TiO2 used in electro-deposition solution, the higher the degradation efficiencies were. Effects of initial dye concentration, initial pH values and applied potentials across the electrodes were investigated. Acidic condition and high potentials applied across the electrodes favored color or TOC removal of the dye. Decolorization rate decreased with an increase in the dye concentration in the range of 5–50 mg/L. Experiments above demonstrate that TiO2 modified β-PbO2 electrode, which realized TiO2 immobilization successfully, performed well in EAPD of Acid Orange 7.