Surface tension measurement of FAP-based ionic liquid pendant drops in a high vacuum/gas cell

Abstract

The surface tension of ionic liquids with the tris(pentafluoroethyl)trifluorophosphate (FAP) anion were measured using a home-built surface tensiometer. A high-vacuum line was used to pre-evacuate the ionic liquids prior to analyses, ensuring that the samples were free of dissolved gases, water, and volatile impurities. Using the pendant drop method, measurements were performed in a custom-built surface tension vacuum or gas cell, in the presence of nitrogen and carbon dioxide gas. To calibrate the instrument, surface tension measurement of known liquids was also performed. Results show that the presence of saturated carbon dioxide led to the lowering of measured surface tension values, indicating the adsorption of CO2 on the ionic liquid surface.