Comparative Study on Decolorization and Degradation of Mono-, Di-, and Triazo Dyes by Electron Beam Radiation

Electron beam (EB) radiation is an emerging technology for the treatment of dye-containing wastewater. However, the structure-degradation relationship of synthetic dyes is still unclear. In this study, EB-induced decolorization efficiencies of typical monoazo, diazo, and triazo dyes exceeded 96.01%, with kinetics that fitted well to the pseudo-first-order kinetic model (R2 > 0.98). Possible degradation mechanisms of these complex azo dyes were proposed, including azo chromophore cleavage, the pathways of substituents, further oxidation and ring-opening of aromatic products, and mineralization. The effect of structural differences on the decolorization and degradation pathways of azo dyestuffs was explored, with particular focus on the number of azo groups. The feasibility of the EB process as the advanced treatment process was proved by evaluating its resistance to complex components and wastewater matrix. This study can offer valuable mechanistic insights into EB-induced degradation pathways and structure-degradation relationship of complex azo dyes, showcasing the substantial promise of the EB technology for the full-scale industrial application in combating dye contamination in future.