In-situ multilevel cladding structure of Cu-Cu2O@Fe/ZnAl-LDH as particle electrode on the degradation of nitrogen-containing disinfection

Abstract

Nitrogen-containing disinfection by-products (N-DBPs) generated during the disinfection of drinking water have received widespread attention for their high cytotoxicity and genotoxicity, which are difficult to remove using traditional treatment techniques, posing a potential threat to the ecological environment and human health. In this study, in-situ multilevel cladding structure of Cu-Cu₂O@Fe/ZnAl-LDH is designed to remove the disinfection by-product trichloroacetamide (TCAcAm). This novel structure benefits from an accelerated electron transfer process and effectively protects Fe from leaching, as demonstrated by modern characterization and analytical techniques, making the composite material promising for excellent electrochemical performance as a particle electrode in our system. The main reason is the introduction of highly active catalytic sites from this multilevel cladding structure, which can enhance the removal efficiency of halogenated nitrogen-containing disinfection by-products. The optimal degradation efficiency of TCAcAm by Cu-Cu₂O@Fe/ZnAl-LDH particle electrode is 96.87 % under the operation conditions of 0.21 mol/L electrolyte, 3.5 mA/cm² current density, and 0.5 L/min flow rate. Based on electron paramagnetic resonance (EPR) measurement and identification of free radical quenching tests, it is elucidated that the removal of TCAcAm is accomplished by the combination of OH, •O₂^–, and ¹O₂. The role of the heterojunction between Cu-Cu₂O@Fe and ZnAl-LDH in pollutant degradation was further investigated using Density Functional Theory (DFT) calculations. The possible degradation pathways of the pollutants are obtained by GC–MS and LC-MS tests.