UV Light-Induced degradation of food dyes in the presence of humic substances-coated iron oxide nanoparticles

This study investigated the photodegradation of amaranth red (AR), sunset yellow (SY), and brilliant blue (BB) food dyes in aqueous solution under UV-A radiation with a maximum wavelength of 350 nm. The synergistic effect of humic substance-coated iron oxide nanoparticles (HS-FeOx) and hydrogen peroxide (H ₂ O ₂ ) was evaluated. While direct irradiation alone was ineffective, the addition of H ₂ O ₂ at a concentration of 0.1 M to the aqueous solution, led to minimal degradation (< 12%). The incorporation of HS-FeOx nanoparticles significantly enhanced the process, particularly for the azo dyes AR and SY. The most effective treatment combined HS-FeOx with H ₂ O ₂ , achieving high degradation percentages of (96.0 ± 0.6) %, (63.3 ± 0.6) % and (46.4 ± 0.1) % for AR, SY, and BB, respectively, after 60 minutes. Control experiments confirmed the oxidative degradation pathway and that Fenton-like reactions occurred even in darkness, though irradiation markedly improved efficiency. The degradation kinetics for all dyes followed a first-order model under the tested conditions.