Electro-catazone treatment of ozone-resistant drug ibuprofen: Interfacial reaction kinetics, influencing mechanisms, and degradation sites

Abstract

Electro-heterogeneous catalytic ozonation (E-catazone) is a promising advanced oxidation process using a unique TiO2 nanoflower (TiO2-NF)-coated porous Ti anode. This study investigated interfacial reaction kinetics and the influencing mechanism of E-catazone degrading ozone-resistant drug ibuprofen. An elementary reactions library of the E-catazone process was established. The kinetic rate of key interfacial reactions under different operation parameters was quantitatively resolved. It was found that parameters such as current, initial pH, O3 concentration, and flowrate mainly affect •OH formation and ibuprofen removal via influencing three key interfacial reactions including anodic TiO2-NF surface hydroxylation, subsequent TiO2-NF‒OH/O3 heterogeneous catalysis, and cathodic generation of H2O2. In addition, the degradation pathways and sites of ibuprofen were also predicted via theoretical chemistry calculation, showing that •OH attacked C(12), C(11), or C(6) atom of the benzene ring in the ibuprofen via a radical adduct formation pathway. The results of this study will guide the application of the E-catazone process in the efficient removal of ozone-resistant drugs.