Solid–Liquid Equilibrium (SLE) of the <i>N</i>,<i>N</i>‑Dimethylacetamide (DMA) + MCl (M = Na, K, Rb, and Cs) + Water Ternary Systems at Multiple Temperatures

We report herein the solid–liquid equilibria (SLE) of <i>N</i>,<i>N</i>-dimethylacetamide (DMA) + MCl (M = Na, K, Rb, and Cs) + H₂O ternary systems for the first time. At the three given temperatures (<i>T</i> = 298.15 K, 308.15 K, and 318.15 K), the solubilities, densities, and refractive indices for these ternary systems are determined with the mass fraction of DMA in salt-free solvent system ranging from 0.0 to 1.0. The solubility of salts decreases significantly with the addition of DMA, and the salting-out ratios are calculated accordingly. The nonrandom two-liquid (NRTL) model can effectively fit the experimental solubility. Furthermore, to investigate the temperature effect on the SLE, the dynamic solubility measurement system is selected to determine the solubility of the salts in the mixed solvent (<i>w</i>_DMA = 0.3, 0.5, and 0.7) with the temperature continuously increased. The solubility data at multiple temperatures are well fitted by the modified Apelblat equation and the λ<i>h</i> equation

Measurements and Correlations of the Solid–Liquid Equilibrium of RbCl/CsCl + [C_<i>n</i>mim]Cl (<i>n</i> = 2, 4, 6, 8) + H₂O Ternary Systems at <i>T</i> = (288.15, 298.15, and 308.15) K

The solubility, density and refractive index of RbCl/CsCl + [C_<i>n</i>mim]Cl (<i>n</i> = 2, 4, 6, 8) + H₂O saturated systems have been studied at <i>T</i> = (288.15, 298.15 and 308.15) K. The solubility data were correlated by the nonrandom two-liquid (NRTL) model and an empirical equation. Both models can qualitatively represent the equilibrium behavior. In addition, the results denote that all the ionic liquids trigger salting-out effects with the order: [C₂mim]Cl > [C₄mim]Cl > [C₆mim]Cl > [C₈mim]­Cl. The density and refractive index of the saturated solutions were determined for describing the relationship between the physical property and composition of the solution

Activity Coefficients of RbF in the RbF + RbBr + H₂O and RbF + RbNO₃ + H₂O Ternary Systems Using the Potentiometric Method at 298.2 K

Thermodynamic properties of the RbF + RbBr + H₂O and RbF + RbNO₃ + H₂O systems were determined by the potentiometric method at the total ionic strengths ranging from 0.0017 to 0.7005 mol·kg^–1 for different ionic strength fractions <i>y</i>_B of RbBr/RbNO₃ with <i>y</i>_B = 0.00, 0.30, 0.60, and 0.90, at 298.2 K. Combining the Nernst equation and Pitzer equation, the mean ionic activity coefficients of RbF and RbBr/RbNO₃, the osmotic coefficients, and the excess Gibbs energies of the studied systems were calculated

Design of Pore Size and Functionality in Pillar-Layered Zn-Triazolate-Dicarboxylate Frameworks and Their High CO₂/CH₄ and C2 Hydrocarbons/CH₄ Selectivity

In the design of new materials, those with rare and exceptional compositional and structural features are often highly valued and sought after. On the other hand, materials with common and more accessible modes can often provide richer and unsurpassed compositional and structural variety that makes them a more suitable platform for systematically probing the composition–structure–property correlation. We focus here on one such class of materials, pillar-layered metal–organic frameworks (MOFs), because different pore size and shape as well as functionality can be controlled and adjusted by using pillars with different geometrical and chemical features. Our approach takes advantage of the readily accessible layered Zn-1,2,4-triazolate motif and diverse dicarboxylate ligands with variable length and functional groups, to prepare seven Zn-triazolate-dicarboxylate pillar-layered MOFs. Six different gases (N₂, H₂, CO₂, C₂H₂, C₂H₄, and CH₄) were used to systematically examine the dependency of gas sorption properties on chemical and geometrical properties of those MOFs as well as their potential applications in gas storage and separation. All of these pillar-layered MOFs show not only remarkable CO₂ uptake capacity, but also high CO₂ over CH₄ and C2 hydrocarbons over CH₄ selectivity. An interesting observation is that the BDC ligand (BDC = benzenedicarboxylate) led to a material with the CO₂ uptake outperforming all other metal-triazolate-dicarboxylate MOFs, even though most of them are decorated with amino groups, generally believed to be a key factor for high CO₂ uptake. Overall, the data show that the exploration of the synergistic effect resulting from combined tuning of functional groups and pore size may be a promising strategy to develop materials with the optimum integration of geometrical and chemical factors for the highest possible gas adsorption capacity and separation performance