Dark blue azo dye degradation by the electro-Fenton process and reaction mechanism prediction via theoretical Fukui function analysis

This study investigates the degradation of dark blue reactive azo (DBA) dye using the electro-Fenton process, with a focus on real-time colour monitoring to identify the most effective cathode-anode combinations for dye removal. Various electrode materials, including platinum (Pt), carbon fibre (C), silver (Ag), and copper (Cu), were tested. The combinations involving carbon fibre achieved a 75% colour removal within the first 20 minutes of electrolysis, whereas those with Pt electrodes did not exceed 15% in the same timeframe across different combinations. The results indicated that the carbon-copper (C-Cu) electrode combination, under optimized conditions, led to approximately 88% dye removal within 120 minutes. A kinetic study using a non-linear method demonstrated that the degradation followed a first-order kinetic model. To better understand the degradation mechanism, the degradation pathway of the DBA dye was predicted through a theoretical analysis using the Fukui function and supported by UV-Vis absorbance spectra, which revealed potential degradation by-products. The experimental data aligned with the theoretical spectra of potential by-products, confirming the electro-Fenton process's effectiveness in breaking down organic dye molecules. The study highlights the superior performance of carbon-based electrodes compared to platinum electrodes and underscores the importance of electrode material selection in optimizing the electro-Fenton process for dye degradation.