Shanbhag, C.C.Iyyaswami, R.Belur, P.D.2026-02-032025Chemical Engineering Research and Design, 2025, 214, , pp. 18-272638762https://doi.org/10.1016/j.cherd.2024.12.020https://idr.nitk.ac.in/handle/123456789/20435The physical properties, density, viscosity, and refractive index of equilibrated phases of the Three-Liquid-Phase System (TLPS) formed by n-Hexane+ethanol+sodium dihydrogen phosphate (NaH<inf>2</inf>PO<inf>4</inf>) +water were determined at 303.15 K and analysed as a function of change in concentration of individual phase forming components. The ternary plots were plotted to locate the shift in three-phase region with variation in system components. It was observed that the increase in total concentration of both ethanol and NaH<inf>2</inf>PO<inf>4</inf> in a system showed a reduction of density and viscosity in the middle phase and was found to increase in the top and bottom phases; however, the refractive index of all three phases was increased. The effect of change in concentration of n-Hexane was observed to be different, like the density and viscosity of top and middle phases were found to decrease with increasing concentration of n-Hexane, and both the properties were found to increase in the bottom phase. In contrast, the refractive index of the top and bottom phases decreased with increasing concentration of n-Hexane. The influence of tie line lengths (TLL), which indicates the equilibrium characteristics between the phases, on the interfacial tension between the phases was also studied. © 2024 Institution of Chemical EngineersDensity of liquidsRefractive indexViscosity index% reductionsDensityDihydrogen phosphateN-HexanePhase formingPropertySystem componentsTernary plotThree-liquid-phase systemThree-phase regionsBulk Density