Electrooxidation degradation of hydroxychloroquine in wastewater using a long-acting Ti-based PbO₂ anode with an...

To solve the challenges facing the low-cost and high-efficiency purification of water pollution caused by the production and metabolism of biodegradable hydroxychloroquine (HCQ), electrooxidation treatment with a Ti-based PbO₂ anode is the most promising technical solution for engineering applications. However, Ti-based PbO₂ anodes have apparent disadvantages, such as poor stability and insufficient electrocatalytic activity. To overcome these shortcomings, a novel Ti/(Ti,Zr)N/PbO₂ anode was prepared by introducing an arc-sprayed (Ti,Zr)N conductive composite interlayer together with a PbO₂ surface layer anodically deposited at different times on a Ti substrate. The electrocatalytic activity, anode stability, optimized parameters and degradation mechanism of the HCQ electrooxidation treatment were experimentally studied. As a result, compared to the Ti/PbO₂ anode without an interlayer, the Ti/(Ti,Zr)N/PbO₂ anode not only showed obviously excellent stability but could also effectively electrocatalytically degrade HCQ. The optimal Ti/(Ti,Zr)N/PbO₂-2.0 anode prepared using the arc-sprayed (Ti,Zr)N interlayer and electrodepositing PbO₂ for 2 h can remove 95.85% of 200 mg L^-1 HCQ at 20 °C and pH 7 after electrolysis at 20 mA cm^-2 for 3 h, and possesses a longer accelerated life with 11.8 times the lifetime of the Ti/PbO₂ anode. Furthermore, after five consecutive periodic electrooxidation treatments, its degradation rate was retained at 86.3% and its Pb²⁺ dissolution concentration (0.0036 mg L^-1) met the requirements of the Chinese standard for drinking water. This long-acting PbO₂ coated anode reveals promising application potential for the electrocatalytic degradation of refractory organic sewage, such as HCQ, which will help to promote the practical popularization of electrooxidation water treatment technology.