Complete Mineralization of Fluorinated Ionic Liquids in Subcritical Water in the Presence of Potassium Permanganate

Abstract

Reactions of [Me3PrN]­[(CF3SO2)2N] and [C3mpip]­[(CF3SO2)2N] (C3mpip = 1-methyl-1-propylpiperidium) in subcritical water were investigated to develop a technique for recycling fluorine element. By adding KMnO4 to the system, quasi-complete mineralization of the ionic liquids was achieved at 300 °C. When [Me3PrN]­[(CF3SO2)2N] was reacted for 18 h with 158 mM KMnO4, F–, SO4 2–, and NO3 – yields were 98, 98, and 91%, respectively, and the amount of total organic carbon (TOC) was below the detection limit. [C3mpip]­[(CF3SO2)2N] was also almost completely mineralized via the same treatment, affording F–, SO4 2–, and NO3 – yields of 94, 97, and 96%, respectively, with no detectable TOC. The rest of the nitrogen atoms were well accounted for by the formation of NO2 –. Compared with a previous reported method using FeO, our approach reduces the reaction temperature for complete mineralization by 76 °C and suppresses the formation of environmentally undesirable CHF3.

Decomposition of Fluorinated Ionic Liquids to Fluoride Ions Using Superheated Water: An Efficient Approach for Recovering Fluorine from the Waste of Fluorinated Ionic Liquids

“…20 To achieve complete mineralization at lower temperature, we examined reactions by oxidative approaches, as described below. 24…”

“…The figure was prepared from Ref. 24 with permission from American Chemical Society and additional data.…”

“…In this comprehensive paper, we describe our recent efforts on the mineralization of two F-ILs, that is, [Me 3 PrN][(CF 3 SO 2 ) 2 N] and 1methyl-1-propylpiperidium bis(trifluoromethanesulfonyl)imide, i.e., [C 3 mpip][(CF 3 SO 2 ) 2 N], and a Li salt Li[(CF 3 SO 2 ) 2 N], using superheated water combined with reducing or oxidizing agents. [22][23][24] The structure of these compounds are illustrated in Fig. 2.…”

Efficient mineralization of a novel fluorotelomer surfactant, 2H,3H,3H,5H,5H,6H,6H-4-thia-perfluoro(2-methyl)-1-dodecanoic acid, in superheated water induced by a combination of potassium permanganate and dioxygen

“…The patterns did not display any diffraction peaks originating from KMnO 4 , while peaks assigned to MnO 2 only were detected. This result is unsurprising because reports on the decomposition of persistent chemicals by treatment with KMnO 4 in superheated water [35][36][37] have indicated that KMnO 4 is converted to MnO 2 (Eq. 4), which then acts as the oxidizing agent.…”

“…Furthermore, KMnO 4 , a harmless oxidizing agent, is employed at tap water manufacturing facilities to treat metal compounds, preventing undesired disinfection products (e.g., trihalomethanes) [34]. So far, there have been only three reports that described KMnO 4 -induced superheated water treatment: destructions of acetic acid [35], poly(vinylidene fluoride) [-(CH 2 CF 2 ) n -] [36], and ionic liquids bearing perfluorinated anions [37].…”