Fish-shaped diagram of liquid–liquid equilibria for the mixtures water + n-alkane + n-alkyl polyglycol ether

The aim of this work is to determine the fish-shaped diagram of liquid–liquid equilibria (LLE) of ternary mixtures of water + n-alkane + n-alkyl polyglycol ether (CiEj) using a cloud point method with laser scattering technique. n-Octane and n-dodecane were selected as the n-alkanes, and 2-butoxyethanol (C4E1) and 2-(2-hexyloxyethoxy)ethanol (C6E2) were selected as the n-alkyl polyglycol ethers. In the measurements of the ternary mixtures, the CiEj free basis mass fraction “α” of n-alkane was changed from 0.1 to 0.9. The experimental fish-shaped diagrams were evaluated by comparing the experimental cloud point data with the fish-shaped diagrams as well as the phase boundaries of tie-line and tie-triangle data in the mixtures of water + n-octane + C4E1 and water + n-dodecane + C6E2 reported in the literature. X-points where the fish body and fish tail intersect were determined from the experimental cloud points, as well as the upper and lower critical point temperature of the fish-body. Changes in the phase diagram and X-points with different n-alkanes, CiEj, and the value of α were analyzed using the experimental data. The LLE data of the mixture of water + C6E2, as one of the binary components of the ternary mixture, was also measured.