Apparent molar volume and isentropic compressibility for the binary systems {methyltrioctylammonium bis(trifluoromethylsulfonyl)imide + methyl acetate or methanol} and (methanol + methyl acetate) at T=298.15, 303.15, 308.15 and 313.15 K and atmospheric pressure

摘要

The densities and speeds of sound for binary mixtures containing the solute ionic liquid (IL) methyltrioctylammonium bis(trifluoromethylsulfonyl)imide ([MOA]~+[Tf_2N]~-), solute/solvent methanol, and solvent methyl acetate have been measured at 298.15, 303.15, 308.15 and 313.15 K at atmospheric pressure. The binary mixtures studied are ([MOA] ~+[Tf_2N]~- + methyl acetate or methanol), and (methanol + methyl acetate). The apparent molar volume, V_φ and the apparent molar isentropic compressibility, k_φ, have been evaluated from the experimental density and speed of sound data, respectively. The parameters of a Redlich-Mayer type equation were fitted to the apparent molar volume and apparent molar isentropic compressibility data. The apparent molar volume and apparent molar isentropic compressibility at infinite dilution, V_φ~0 and k_φ~0, respectively, of the binary solutions have also been calculated at each temperature. The infinite dilution apparent molar volume indicates that intermolecular interactions for (IL + methyl acetate) mixtures are stronger than for (IL + methanol) mixtures at all temperatures except at 298.15 K, and that V _φ~0 for the (IL + methyl acetate or methanol) binary systems increases with an increase in temperature. For the (methanol + methyl acetate) system the intermolecular interaction are weaker and V _φ~0 also increases with an increase in temperature. Values of the infinite dilution apparent molar expansibility, E _φ~0, indicate that the interaction between (IL + methyl acetate) is greater than for (IL + methanol) and (methanol + methyl acetate). The isentropic compressibilities increase with an increase in temperature for each binary system. At a fixed temperature the isentropic compressibilities also increase with an increase in concentration of the solute for the systems (IL + methyl acetate) and (methanol + methyl acetate), but decrease for the system (IL + methanol). Negative values of k_φ~0 for ([MOA] ~+[Tf_2N]~- + methyl acetate or methanol) and (methanol + methyl acetate) mixtures can be attributed to the predominance of a penetration effect resulting in greater resistance to compression.