Effect of a fluorinated sodium bis(2-ethylhexyl) sulfosuccinate (aerosol-OT, AOT) analogue surfactant on the interfacial tension of CO ₂ + water and CO₂ + Ni-plating solution in near- and supercritical CO₂

The effect of a fluorinated sodium bis(2-ethylhexyl) sulfosuccinate (aerosol-OT, AOT) analogue surfactant (sodium salt of bis(2,2,3,3,4,4,5,5- octafluoro-1-pentanol) sulfosuccinate) on the interfacial layer of supercritical CO₂ + water and supercritical CO₂ + Ni-plating solution systems was investigated by measuring via the capillary rise method. These interfacial tensions were measured in the pressure range of (0.1 to 20.0) MPa at multiple temperatures for each of five interfaces: (1) CO₂ + water system at (293.15, 298.15, 311.15, and 344.15) K; (2) CO₂ + Ni-plating solution system at (313.15, 328.15, and 344.15) K; (3) CO₂ + Ni-plating solution + F-AOT surfactant (0.1 and 0.3 mass %) system at (313.15, 328.15, and 344.15) K; (4) CO₂ + Ni-plating solution + ethanol (10 and 20 vol %) system at 328.15 K; and (5) CO₂ + Ni-plating solution + F-AOT surfactant (0.1 mass %) + ethanol (10 vol %) system at (313.15, 328.15, and 344.15) K. The reliability of the apparatus was confirmed by comparing the experimental data with literature data for the CO₂ + water system at (311.15 and 344.15) K The individual addition of the F-AOT surfactant and ethanol reduced the interfacial tension for the CO₂ + Ni-plating solution system; however, the simultaneous addition of these two substances caused the opposite effect on the interfacial tension.