Oxalate Enhanced Organic Pollutant Removal with a UV/Fe0 System: Performance, Mechanisms, and Role of Oxalate
2021
Pan, Yuwei | Bu, Zhuoyu | Li, Xiang | Han, Jiangang
This study presented the efficient removal of tartrazine, a typical biorefractory dye, in a heterogeneous photochemical Fenton-like system adopting Fe⁰ and oxalate (Ox) (UV/Fe⁰/Ox). Only 47.4% tartrazine could be removed within 60 min with a UV/Fe⁰ system. The addition of Ox could significantly enhance the removal of tartrazine to 72.4% within only 20 min with the UV/Fe⁰/Ox system. The effects of various factors, such as the Fe⁰ dose (0–0.8 g/L), Ox dose (0–2 mM), initial pH (2–6), and initial tartrazine concentration (2–30 mg/L), on the removal of tartrazine were examined. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and Mossbauer spectroscopy were conducted to explore the mechanism by which oxalate enhances the performance of the UV/Fe⁰ system. Ox could inhibit the formation of iron (hydro)xides on the Fe⁰ surface, thus guaranteeing the reactivity of Fe⁰ during the reaction. Compared with Fe₂O₃, FeS, and Fe₃O₄, Fe⁰ was a good heterogeneous iron catalyst for the photolysis of tartrazine with the Ox system. Compared with H₃PO₄, nitrilotriacetic acid, and ethylenediaminetetraacetic acid, Ox was also a good photolysis chelating agent. The UV/Fe⁰/Ox system could also maintain fast tartrazine removal after five consecutive runs without the addition of Fe⁰, indicating the good stability of Fe⁰.
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