Electrooxidation degradation of hydroxychloroquine in wastewater using a long-acting Ti-based PbO2 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 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. [Display omitted] •A Ti/(Ti,Zr)N/PbO2-coated anode was prepared for electrooxidation treatment.•96.14% of HCQ in wastewater could be removed under optimal conditions.•Inclusion of sprayed (Ti,Zr)N interlayer obviously prolonged PbO2 anode lifetime.•(Ti,Zr)N composite interlayer promoted electrocatalytic activity of PbO2.•Recommended PbO2 surface coating electrodeposition time was less than 2 h.