Decomposition of Perfluorinated Ionic Liquid Anions to Fluoride Ions in Subcritical and Supercritical Water with Iron-Based Reducing Agents

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• 作者：Hisao Hori ; Yoshinari Noda ; Akihiro Takahashi ; Takehiko Sakamoto
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2013
• 出版时间：September 25, 2013
• 年：2013
• 卷：52
• 期：38
• 页码：13622-13628
• 全文大小：380K
• 年卷期：v.52,no.38(September 25, 2013)
• ISSN：1520-5045

文摘

Decomposition of perfluorinated ionic liquid anions [(CF₃SO₂)₂N]^{鈭?/sup> and [(C₄F₉SO₂)₂N]鈭?/sup> in subcritical and supercritical water was investigated with the aim of developing a technique to recover the fluorine component from ionic liquid wastes. Addition of zerovalent iron to the reaction system dramatically increased the yield of F鈥?/sup>: when the reaction of [(CF₃SO₂)₂N]鈭?/sup> was carried out at 344 掳C for 6 h, the F鈥?/sup> yield was 69.0%, which is 186 times the yield without iron. Increasing the temperature and reaction time in the presence of zerovalent iron further increased the yield: when [(CF₃SO₂)₂N]鈭?/sup> and zerovalent iron were heated in supercritical water at 375 掳C for 18 h, 76.8% of the fluorine content in the initial [(CF₃SO₂)₂N]鈭?/sup> was transformed into F鈥?/sup>. [(CF₃SO₂)₂N]鈭?/sup> also decomposed in the presence of FeO, which underwent in situ disproportionation to form zerovalent iron, which acted as the reducing agent. Although the FeO-induced decomposition of [(CF₃SO₂)₂N]鈭?/sup> was initially slower than the zerovalent iron-induced decomposition, after prolonged reaction (18 h) at 378 掳C, the F鈥?/sup> yield of the former reaction reached 85.7%, which was the highest yield obtained. This result suggests that the zerovalent iron that formed in situ reacted preferentially with the substrate, as opposed to water.}