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A new ionic liquid, tris(monoethanolamine) citrate (TMEAC), was synthesized and characterized by FT-IR spectrometry and 1 H NMR. Densities and viscosities of aqueous TMEAC mixtures were determined at 293.15-323.15 K and atmospheric pressure. The thermal expansion coefficient a, excess molar volume V E m , and excess logarithm of viscosity (ln g) E were calculated to evaluate the properties of the aqueous TMEAC ionic liquid. Correlation equations were fitted using these data for the calculation of density and viscosity. The results show that the density increases almost linearly as the mass fraction of TMEAC increases. The mass fraction of TMEAC has little influence on the density at low mass fraction. The viscosity changes significantly and sharply increases at mass fractions larger than 60 %. Both density and viscosity decrease as the temperature increases. The thermal expansion coefficient initially decreases and then increases with increase of the mass fraction of TMEAC. The change of the excess molar volume presents a W-shape. The excess logarithm of viscosity shows a variation where the value initially rises but subsequently drops. Values calculated from the correlation equations are in good agreement with the experimental values. The correlation equations can offer additional results for the aqueous TMEAC ionic liquid.Electronic supplementary material The online version of this article (

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Piperazine (PZ) as an additive was added into a solution of potassium citrate (PC) to form a novel complex solution of the aqueous (PC + PZ) system. Research for the physical properties, density, viscosity, and surface tension, of the aqueous (PC + PZ) system was carried out. Densities and viscosities of the aqueous (PC + PZ) system have been determined at (293.15, 303.15, 313.15, and 323.15) K, and surface tensions of the aqueous (PC + PZ) system have been measured at 293.15 K. Correlations for the physical properties were fitted using the method of mathematics. Predictions of the physical properties of the aqueous (PC + PZ) system were conducted. Performances were compared and discussed between the (PC + PZ) system and other complex systems such as the (PG (glycinate) + PZ) system. Results show that the densities and viscosities of the aqueous (PC + PZ) system decrease with the increase of temperature and PZ mole fraction in the system. The surface tensions of the studied system decrease as the PZ mole fraction in the system increases at 293.15 K. The physical properties of the aqueous (PC + PZ) system are basically similar to that of the aqueous (PG + PZ) system. As opposed to the (PG + PZ) system, the viscosity of the aqueous (PC + PZ) system decreases, while the viscosity of the aqueous (PG + PZ) system increases as the PZ mole fraction in the system increases. The surface tension of the aqueous (PG + PZ) system decreases linearly, while the surface tension of the aqueous (PC + PZ) system is nonlinear with the increase of PZ mole fraction in the system. The prediction values from correlations for the physical properties are in good agreement with the experimental values. The correlations for the physical properties of the aqueous (PC + PZ) system can offer additional data.