Vapor-Pressure Measurement of Ternary System CaCl₂ + [Emim]Br + H₂O, CaCl₂ + [Emim]Cl + H₂O, CaCl₂ + [Emim]Ac + H₂O, and CaCl₂ + [Emim]NO₃ + H₂O

Abstract

Calcium chloride (CaCl 2 ) aqueous solution as a liquid desiccant has the disadvantage of low vapor pressure and easy crystallization. Ionic liquids (ILs) such as [Emim]Cl, [Emim]Ac, and [Emim]Br have been verified to have a good ability to reduce the vapor pressure. In this paper, the vapor pressures of four kinds of CaCl 2 + ILs + H 2 O were measured, which were CaCl 2 + [Emim]Br + H 2 O (mass ratio CaCl 2 / [Emim]Br = 2:1) at temperatures of between 311.10 and 394.45 K, CaCl 2 + [Emim] Cl + H 2 O (mass ratio CaCl 2 /[Emim]Cl = 2:1) at temperatures of between 306.58 and 393.89 K, CaCl 2 + [Emim]Ac + H 2 O (mass ratio CaCl 2 /[Emim]Ac = 2:1) at temperatures of between 304.93 and 382.71 K, and CaCl 2 + [Emim]NO 3 + H 2 O (mass ratio CaCl 2 /[Emim]NO 3 = 2:1) at temperatures of between 312.46 and 391.80 K, with the mass fraction of solute ranging from 0.2 to 0.5. The Antonie-type equation was used to fit the measured results. The average absolute relative deviation (AARD %) values of the measured vapor pressures and calculated vapor pressures were 0.52, 0.40, 0.33, and 0.27%, which showed good consistency and accuracy. Comparing the vapor pressures of the different solutions at the same concentration, the following order of the four anions with the ability to reduce the vapor pressure of CaCl 2 + H 2 O can be drawn at a mass fraction of 0.4: Br − > Cl − > NO 3 − > Ac − .

Study on vapor–liquid equilibrium and microscopic properties of DL-proline, L-glutamic acid, and L-serine aqueous solutions

“…As shown in Figure 3 , the saturated vapor pressures of the three different amino acid aqueous solutions in the saturated state are also different due to the different solubilities at the same temperature. In addition, it can be seen that with the increase in temperature, the saturated vapor pressure of amino acids increases continuously, which is consistent with the description in the literature ( Ding et al, 2021 ).This could be caused by the same temperature. For the same volume of solution sample, the number of solvent molecules in the unit volume and unit surface of the sample with greater solubility decreases.…”

Vapor Pressure Measurement of Ternary Systems LiCl + [Emim]I + H2O and LiCl + [Dmim]I + H2O

“…The schematic diagram of the experimental apparatus is illustrated in Figure . The detailed information of the experimental apparatus was introduced in previous publications. − The uncertainties of the temperature sensor and the silicon pressure sensor were ±0.05 K and ±0.064 kPa, respectively. The boiling point method was adopted in the vapor pressure measurement procedure.…”

“…Schematic diagram of the experimental apparatus: 1, computer; 2, oil bath with a magnetic stirrer; 3, water pump; 4, water tank; 5, Agilent dynamic signal analyzer; 6, equilibrium; 7, buffer bottle; 8, vacuum pump; 9, spherical condenser; 10, silicon pressure sensor; 11, temperature sensor; 12, clamp; 13, air inlet; 14, high vacuum valve. − …”

“…Vapor–liquid equilibrium (VLE) data of IL mixtures are of particular interest to researchers. ,− Because vapor pressure data indicates the mixtures’ water absorption properties and by using VLE data and other thermodynamic properties’ information, absorption system performance can be further studied. − For example, the performance of absorption heat transformers can be evaluated by the experimentally measured thermodynamic properties; data (VLE, heat capacity data, and so on) of two binary IL mixtures ([Dmim]­MeSO 4 + H 2 O and [Emim]­MeSO 4 + H 2 O) were used for simulation . VLE and other property data of two IL mixtures (TFE + [Emim]­BF 4 and TFE + [Bmim]­BF 4 ) are used for modeling two absorption heat transformer cycles .…”

“…In our previous work, the VLE data of several selected ILs with LiCl + H 2 O, LiBr + H 2 O, CaCl 2 + H 2 O, and HCOOK + H 2 O were measured by the boiling point method. These measured ternary mixtures are LiBr + [Emim]Ac + H 2 O, LiCl + [Emim]Cl + H 2 O, LiBr + [Emim]Cl + H 2 O, LiCl + [Emim]Br + H 2 O, LiBr + [Emim]I + H 2 O, LiBr + [Dmim]I + H 2 O, CaCl 2 + [Emim]Br + H 2 O, CaCl 2 + [Emim]Cl + H 2 O, CaCl 2 + [Emim]Ac + H 2 O, CaCl 2 + [Emim]­NO 3 + H 2 O, HCOOK + [Emim]Ac + H 2 O, HCOOK + [Emim]Br + H 2 O, HCOOK + [Emim]Cl + H 2 O, and HCOOK + [Emim]­NO 3 + H 2 O. − By experimentally measured VLE data, it was found that (i) the proposed IL additives can reduce the vapor pressure of the aqueous solutions to a certain extent; (ii) the types of anions in the ILs are essential for the water affinity properties of the IL mixtures; IL mixtures of the same organic cations and different anions have different hydrophilic properties. For example, the order of vapor pressures is LiBr + [Emim]I + H 2 O < LiBr + [Emim]Cl + H 2 O < LiBr + [Emim]Ac + H 2 O.…”