Hydroxyl and sulfate radicals activated by Fe(III)-EDDS/UV: Comparison of their degradation efficiencies and influence of critical parameters

Xiaoning Wang (1, 2) , Wenbo Dong (3) , Marcello Brigante (2) , Gilles Mailhot (2)

1 LAP3 - Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention
2 ICCF - Institut de Chimie de Clermont-Ferrand
3 Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai

In the present study, comparison of activation efficiencies of hydrogen peroxide (H2O2) and persulfate (PS, Na2S2O8) induced by Fe(III)-Ethylenediamine-N,N'-disuccinic acid (EDDS) under polychromatic irradiation UVA and visible region at same conditions was studied for the first time. The effects of pH, Fe(III)-EDDS concentration, H2O2 and PS concentrations were investigated. p-hydroxyphenylacetic acid (p-HPA) was taken as a model pharmaceutical intermediate pollutant to estimate the oxidative process efficiency. In these two systems, the degradation rate of p-HPA increased (not linearly) using higher concentrated solution of H2O2 and Na2S2O8. However, when Fe(III)-EDDS concentration exceeding 250 μM, the degradation efficiency of p-HPA began to decrease. Surprisingly, results of pH effects showed that Fe(III)-EDDS/H2O2/UV system presents much higher degradation efficiency than Fe(III)-EDDS/PS/UV whatever the solution pH’s, especially in neutral and alkaline solutions. In the Fe(III)-EDDS/H2O2/UV reaction, p-HPA degradation rate (Rp-HPA) increased fast from pH 2.5 to 7.5, then it began to decrease when pH increased to 9.0. While Rp-HPA started to decrease with pH increase to 3.9 in Fe(III)-EDDS/PS/UV system. To explain this phenomenon, the second order constant of p-HPA (for both molecular and mono-anionic forms) with HO and SO4− radicals were determined by laser flash photolysis (LFP) experiments for the first time. Results showed that was higher than for both anionic and molecular forms of pollutant. These results demonstrated that iron-complex induced photo-Fenton process is more efficient than activation of persulfate process, particularly at environmentally closed pH values and sun-simulated wavelengths (λ > 300 nm).

Mots clés: Advanced oxidation processes; Iron-EDDS complexes; Decontamination; Wastewater

Domaines: Chimie

Xiaoning Wang, Wenbo Dong, Marcello Brigante, Gilles Mailhot. Hydroxyl and sulfate radicals activated by Fe(III)-EDDS/UV: Comparison of their degradation efficiencies and influence of critical parameters. Applied Catalysis B: Environmental, 2019, 245, pp.271-278. ⟨10.1016/j.apcatb.2018.12.052⟩. ⟨hal-02190114⟩