Embedding wasted hairs in Ti/PbO₂ anode for efficient and sustainable electrochemical oxidation of organic wastewater

Despite of the hazardous risk of Pb²⁺ leakage, lead dioxide has been attributed as a quasi-ideal anode material with high oxygen evolution potential, excellent conductivity, good stability and low cost in electrochemical oxidation wastewater treatment technique. In this study, a novel Ti/PbO₂ anode was fabricated by embedding raw materials that are readily and cheaply available, i.e., hairs. The structure-activity relationship of the new electrode was firstly revealed by material and electrochemical characterizations. Then different levels of pollutants (azo dye, phenol and maleic acid) were used to investigate the electrochemical oxidation performance of the new electrode. Finally, the accelerated electrode lifetime and Pb²⁺ leakage tests were carried out. Results showed that the embedded hairs changed the preferential crystallographic orientation of PbO₂ and decreased the grain size. Hairs introduced additional roughness and active sites, and decreased the electrode impedance, especially under 5 mg/cm² of embedding amount. The removal efficiencies of different target pollutants were enhanced more or less by embedding appropriate amount of hairs, depending on the current density, but loading excessive hairs had a negative effect. The accumulation of intermediate products during phenol degradation was also changed by the hairs. The new electrode could undergo ∼550 h of harsh electrolysis. It is also relieved that the Pb²⁺ leakage was found to be suppressed during this long-term electrolysis process.