نبذة مختصرة : Dechlorination of chloropyridines can eliminate their detrimental environmental effects. However, traditional dechlorination technology cannot efficiently break the C–Cl bond of chloropyridines, which is restricted by the uncontrollable nonselective species. Hence, we propose the carbonate species-activated hydrogen peroxide (carbonate species/H 2 O 2 ) process wherein the selective oxidant (peroxymonocarbonate ion, HCO 4 – ) and selective reductant (hydroperoxide anion, HO 2 – ) controllably coexist by manipulation of reaction pH. Taking 2-chloropyridine (Cl–Py) as an example, HCO 4 – first induces Cl–Py into pyridine N-oxidation intermediates, which then suffer from the nucleophilic dechlorination by HO 2 – . The obtained dechlorination efficiencies in the carbonate species/H 2 O 2 process (32.5–84.5%) based on the cooperation of HCO 4 – and HO 2 – are significantly higher than those in the HO 2 – -mediated sodium hydroxide/hydrogen peroxide process (0–43.8%). Theoretical calculations confirm that pyridine N-oxidation of Cl–Py can effectively lower the energy barrier of the dechlorination process. Moreover, the carbonate species/H 2 O 2 process exhibits superior anti-interference performance and low electric energy consumption. Furthermore, Cl–Py is completely detoxified via the carbonate species/H 2 O 2 process. More importantly, the carbonate species/H 2 O 2 process is applicable for efficient dehalogenation of halogenated pyridines and pyrazines. This work offers a simple and useful strategy to enhance the dehalogenation efficiency of halogenated organics and sheds new insights into the application of the carbonate species/H 2 O 2 process in practical environmental remediation.
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