Preparation and characterization of a novel blue-TiO2/PbO2-carbon nanotube electrode and its application for degradation of phenol

In this study, we fabricated a blue-TiO2/PbO2-carbon nanotube (CNT) electrode in which blue TiO2 nanotube arrays (blue-TNA) served as the substrate for PbO2-CNT eletrodeposition. Scanning electron microscope (SEM) showed compact surface structure of the electrode. The β-PbO2 crystal structure was detected by X-ray diffraction (XRD). The distribution of Pb, O, C, and Na elements on the electrode surface have been confirmed by X-ray photoelectron spectroscopy (XPS). Blue-TiO2/PbO2-CNT electrode had higher response current (213.12 mA), larger active surface area and lower charge transfer resistance (2.22 Ω/cm2) than conventional TiO2/PbO2-CNT electrode. The influences of current density, initial phenol concentration, initial solution pH, and Na2SO4 concentration on the electrochemical oxidation of phenol have been analyzed. The results showed that the 100 mg/L phenol could be destroyed completely after 210 min, and chemical oxygen demand (COD) removal rate was 89.3% within 240 min. Additionally, the electrode showed long actual lifetime (5468.80 hr) and low energy consumption (0.08 kWh/gCOD). A phenol degradation mechanism was proposed by analyzing the intermediate products with high-performance liquid chromatography-mass spectrometry (HPLC-MS). Importantly, the blue-TiO2/PbO2-CNT electrode exhibited superior stability and high degradation efficiency after 15 times reuse, demonstrating its promising application potential on phenol-containing wastewater treatment.