Subcritical Water-Driven Complete Mineralization of Silane Coupling Agents with Short Perfluoroalkyl Chains

The decomposition of CF₃CH₂CH₂Si-(OMe)₃ and C₄F₉CH₂CH₂Si-(OMe)₃typical fluorinated silane coupling agents used for surface modificationwas investigated in subcritical water for potential waste treatment applications. When CF₃CH₂CH₂Si-(OMe)₃ was heated in subcritical water with no additive at 350 °C, only a small amount of fluoride (F^-) was produced. In contrast, virtually complete mineralization of CF₃CH₂CH₂Si-(OMe)₃ was achieved in the presence of KMnO₄. Specifically, after treatment with 0.50 mmol of KMnO₄ for 6 h, the F^- yield reached 100%, and the residual total organic carbon in the reaction solution was reduced to 4% of the initial carbon content of CF₃CH₂CH₂Si-(OMe)₃. Furthermore, under the same reaction conditions, quasi-complete mineralization of C₄F₉CH₂CH₂Si-(OMe)₃ was also attained, with an F^- yield of 96% and a remaining TOC ratio of 2%.