Electrooxidation degradation of hydroxychloroquine in wastewater using a long-acting Ti-based PbO anode with an arc-sprayed (Ti,Zr)N interlayer.

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 PbO anode is the most promising technical solution for engineering applications. However, Ti-based PbO anodes have apparent disadvantages, such as poor stability and insufficient electrocatalytic activity. To overcome these shortcomings, a novel Ti/(Ti,Zr)N/PbO anode was prepared by introducing an arc-sprayed (Ti,Zr)N conductive composite interlayer together with a PbO 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/PbO anode without an interlayer, the Ti/(Ti,Zr)N/PbO anode not only showed obviously excellent stability but could also effectively electrocatalytically degrade HCQ. The optimal Ti/(Ti,Zr)N/PbO-2.0 anode prepared using the arc-sprayed (Ti,Zr)N interlayer and electrodepositing PbO for 2 h can remove 95.85% of 200 mg L HCQ at 20 °C and pH 7 after electrolysis at 20 mA cm for 3 h, and possesses a longer accelerated life with 11.8 times the lifetime of the Ti/PbO anode. Furthermore, after five consecutive periodic electrooxidation treatments, its degradation rate was retained at 86.3% and its Pb dissolution concentration (0.0036 mg L) met the requirements of the Chinese standard for drinking water. This long-acting PbO 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.