Efficient Technique for Simultaneous Lead Recovery and PbO₂/Ti Electrode Preparation for Electrocatalytic Degradation of Basic Red.

Abstract

In order to achieve the effective removal of Pb2+ from low-concentration wastewater as well as the lead recovery for direct reuse simultaneously, a simple electrodeposition method was used in this study. In this process, synthetic lead wastewater with low concentration of 4, 8, 12 and 16 mg/L was treated, more than 67% lead was recovered from wastewater and a PbO₂/Ti electrode was fabricated in a simple reaction tank. The test results of characterizations confirmed that PbO₂ nanoeletrocatalyst was successfully deposited on a Ti substrate. Electrochemical activity tests indicated that PbO₂/Ti electrode had advantages of high oxygen evolution potential (1.90 V) and low electron transfer resistance. Furthermore, the results of electrocatalytic degradation experiments demonstrated that prepared PbO₂/Ti electrode had the superb decolorization and mineralization ability on Basic Red. After 120 min of electrolysis, the Basic Red removal efficiency and TOC removal efficiency could reach to 89.38% and 68.82%, respectively, which was 5.2 and 7.1 times higher than the Ti substrate alone. Besides, the calculated mineralization current efficiency for PbO₂/Ti electrode increased from 5.18% to 36.74% after PbO₂ depositing, and thus an economical benefit was obtained by more than 5 times energy saving. The influences of the applied current density, initial dye concentration, electrolyte concentration and solution pH on the oxidation efficiency were also investigated and optimized. The prepared PbO₂/Ti electrode also showed a great stability with high dye removal efficiency (above 85%) after 10 times repeated experiments. These results suggest that it is a promising technological process to remove and recover lead from low-concentration wastewater efficiently and reuse them as electrocatalyst for other organic wastewater treatments.