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UNIQUAC
About: UNIQUAC is a research topic. Over the lifetime, 2908 publications have been published within this topic receiving 53973 citations.
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TL;DR: In this paper, the authors evaluated the gas-liquid equilibrium of two ionic liquids, 1-butyl-3-methylimidazolium dicyanamide (DCA), with carbon dioxide (CO2) at temperatures up to 363 K and pressures up to 74 MPa.
Abstract: The acidity/basicity of the reaction media has a substantial influence on the efficiency of many reactive processes; therefore, a new class of acidic or basic ionic liquids is gaining special attention due to the possibility of increasing the efficiency of many processes by a wise manipulation of their properties. The absorption of sour gases is one of the processes that can be enhanced by the basic character of the ionic liquid. The fluorination of the cation or anion can also contribute to the gas solubility enhancement. In this work, these two characteristics are evaluated and compared through the study of gas–liquid equilibrium of two ionic liquids, 1-butyl-3-methylimidazolium dicyanamide ([C4mim][DCA]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][Tf2N]), with carbon dioxide (CO2) at temperatures up to 363 K and pressures up to 74 MPa. A thermodynamic model based on the Peng–Robinson equation of state with the Wong–Sandler mixing rule, using the UNIQUAC model for the activity coefficients, was used to describe the experimental data and for the estimation of the Henry's constants. The solubility of CO2 in 1-butyl-3-methylimidazolium dicyanamide is much lower than anticipated on the basis of the reported pKa of the anion when compared with the acetate anion. No chemisorption is observed and the solvation enthalpy is quite low, ruling out any Lewis acid/base interaction between the anion and the CO2. The 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid, known to present one of the highest solubilities towards CO2 due to the presence of fluoroalkyl groups, showed a much larger solubility for CO2 than 1-butyl-3-methylimidazolium dicyanamide.
170 citations
TL;DR: In this article, an extended UNIQUAC model is used to describe phase behaviour (VLE, SLE) and thermal properties (heat of mixing, heat capacity) for aqueous solutions containing ions like (Na +, K +, H + ) (Cl −, NO 3 −, SO 4 2−, OH −, CO 3 2−, HCO 3 − ).
168 citations
TL;DR: In this article, two new expressions for the excess Gibbs energy of liquid mixtures are derived from Guggenheim's quasi-lattice model and Wilson's local composition concept.
163 citations
TL;DR: In this article, a modified version of the Sander model for predicting salt effects on vapor-liquid equilibria (VLE) has been proposed, which combines a Debye-Huckel term with a modified UNIQUAC equation with concentration-dependent parameters.
163 citations
TL;DR: Experimental binary and ternary equilibrium data for the adsorption of hydrocarbon mixtures of methane, ethane, ethylene, and propylene on activated carbon at 20°C are presented and discussed in this paper.
Abstract: Experimental binary and ternary equilibrium data for the adsorption of hydrocarbon mixtures of methane, ethane, ethylene, and propylene on activated carbon at 20°C are presented and discussed. Reproduction of binary adsorption equilibria and prediction of ternary adsorption equilibria exclusively with data of binary systems have been carried out using a real adsorbed solution theory, which requires the calculation of the activity coefficients for the components in the adsorbed phase.
Predicted equilibrium data are found to be in excellent agreement with experimental values using Wilson and UNIQUAC equations to calculate the activity coefficients. The real absorbed solution theory provides a much more accurate method for predicting multicomponent adsorption equilibria than the ideal adsorbed solution theory.
159 citations