A novel NiFe-LDH/AC three-dimensional particle electrode system and its application for degradation of N-nitrosamines: Condition optimization and degradation mechanism

A green and sustainable three-dimensional particle electrodes system with nickel-iron layered double hydroxide mixing activated carbon particles (NiFe-LDH/AC) as particle electrodes is used in this work. Its employment in degradation of N-Nitrosodiethylamine (NDEA), A type of nitrosamines disinfection byproducts (NAs) widely present in water bodies, exhibiting significant degradation efficiency at close to neutral pH. Response surface methodology (RSM) is used to analyze the interaction effects and predict optimal conditions of four operating parameters (influent water flow, electrolyte concentration, current density and initial concentration) on the NDEA degradation efficiency. Calculated coefficients of determination (R2) are higher than 0.997 for all responses according to analysis of variance. At optimum conditions, a maximum degradation efficiency of 71.88% is achieved for NDEA. The results of electron paramagnetic resonance (EPR) and free radical quenching experiments indicate that the degradation of NDEA in the 3D AER system is dominated by •OH. Furthermore, based on the recognition of main reaction intermediates by GC-MS and density functional theory (DFT), possible degradation pathway is proposed and toxicological evaluation of degradation products is made. Our research provides a promising alternative method for the efficient and environmentally friendly removal of NAs from water.