Gallic acid degradation by electron beam irradiation under various conditions
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In this study, aqueous solutions of gallic acid (GA) were irradiated in an electron beam (EB) accelerator under different experimental conditions (various initial GA concentrations, presence or absence of oxidant and oxygen). For an initial GA concentration of 50 μM, complete GA degradation was achieved with an absorbed dose of 850 Gy in the presence of dissolved oxygen. Both GA removal and mineralization are favored when oxygen is present. The addition of persulfate anions (S2O82−) or hydrogen peroxide (H2O2) also increased the efficiency of GA degradation and mineralization. For an absorbed dose of 14 kGy, GA mineralization reached approximately 45%, 55%, and 72% for the EB, EB/H2O2, and EB/S2O82−systems, respectively. Three transformation products were tentatively identified in the presence of oxygen, these are the result of hydroxylation and ring opening reactions. No specific transformation product was found for the sulfate radical anion (SO4–●) reaction. Four additional compounds, including a dimer, were identified in oxygen-free solutions. These findings demonstrate that water radiolysis based on EB irradiation is an efficient process to activate H2O2 and S2O82− anions and is an advanced oxidation process (AOP).
KeywordsWater radiolysis Hydroxybenzoic acid Persulfate anions Oxygen Transformation products Electron beam Gallic acid
The authors acknowledge financial support from the European Union (ERDF) and “Région Nouvelle Aquitaine.” The authors would like to acknowledge King Abdulaziz City for Science and Technology (KACST) for financially supporting Dr. T. S. Alkhuraiji via a grant. The authors are also grateful to Sylvie Liu for her valuable assistance in the LC/MS analyses.
The Université de Poitiers, France, supported this work.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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