Preparation of Ti/SnO2–Sb/La-βPbO2 electrode and its application in the degradation of some pollutants including prednisolone and 8-Hydroxyquinoline

Abstract

In this work, a novel La-doped βPbO2 (Ti/SnO2–Sb/La-βPbO2) was prepared using electrodeposition method and applied to the degradation of prednisolone (PRD), 8-Hydroxyquinoline (8-HQ), and other typical organic pollutants. Compared with the conventional electrode Ti/SnO2–Sb/βPbO2, La2O3 doping enhanced oxygen evolution potential (OEP), reactive surface area, stability and repeatability of the electrode. The 10 g L−1 of La2O3 doping exhibited the highest electrochemical oxidation capability of the electrode with [•OH]ss being determined at 5.6 × 10−13 M. The quenching experiments were conducted to confirm the main oxidizing species (here: •OH) in the electrochemical process. The study showed that the pollutants were removed in the electrochemical (EC) process with different degradation rates and indicated that the second-order rate constant of organic pollutants towards •OH (kOP,•OH) has a linear relationship with the degradation rate of organic pollutants (kOP) in the electrochemical process. Another new finding in this work is that a regression line of kOP,•OH and kOP can be used to estimate kOP,•OH of an organic chemical, which cannot be determined using the competition method. kPRD,•OH and k8-HQ,•OH were determined to be 7.4 × 109 M−1 s−1 and (4.6–5.5) × 109 M−1 s−1, respectively. Compared with conventional supporting electrolyte (like SO42−), H2PO4− and HPO42− improved kPRD and k8-HQ by 1.3–1.6-fold, while SO32− and HCO3− inhibited kPRD and k8-HQ significantly, down to 80%. Additionally, the degradation pathway of 8-HQ was proposed based on the detection of intermediates from GC-MS.