In
the present work, densities (ρ) and viscosities (η) of binary
liquid mixtures of cyclic alcohols and ethylene glycol have been measured
over the whole composition range at different temperatures (293.15–318.15
K), under atmospheric pressure (0.1 MPa). The mixing functions like
excess molar volumes (V
m
E) and viscosity deviation (Δη)
have been calculated and further fitted with the Redlich–Kister
equation. For the system of cyclopentanol (2) + ethylene glycol (1),
the V
m
E values were asymmetric and positive and reach a maximum around x
2 = 0.7, and for the rest of the system, these
maxima appear around 0.6, 0.5, and 0.58, respectively. Δη
values are negative and were also correlated with the algebraic Redlich–Kister
equation.
In the present work, density (ρ) calculations, molecular dynamics (MD) simulations, and quantum chemical calculations of pseudo-binary mixtures of aminobutyric acid and L-valine in aqueous solutions of sodium thiosulfate (Na 2 S 2 O 3 ) at T = 283.15 to 318.15 K and atmospheric pressure (0.1 MPa) were performed. MD simulations reveal the formation of molecular aggregates induced by the preferential solvation in the mixture, due to the electrostatic interactions at the first layer of solvation between the charged groups of amino acids and the inorganic salt. The formation of these molecular aggregates is promoted by an increase in the salt concentration. Noncovalent interactions within the pseudo-binary mixtures were studied by the noncovalent interaction index (NCI) and IGM analysis, which well supported the experimental findings.
In the present work, densities (ρ) of glycine, l-alanine, aminobutyric acid, l-valine, and l-leucine
in an aqueous solution of calcium acetate (0.2005; 0.5998; 0.9000;
1.1978; and 1.5991) mol kg–1 have been measured
at T = 293.15–308.15 K and pressure P = 0.1 MPa. The infinite dilution apparent molar volumes
(V
φ
0) and standard volumes of transfer (Δtr
V
φ
0) vary linearly with those of carbon atoms
in the alkyl chain of the amino acids. The contributions of the nonpolar
groups to the value of V
φ
0 increase with the size of the alkyl
chain of amino acids and decrease with the concentration increase
of calcium acetate. The group-contribution of charged end groups (NH3
+, COO–) is larger than that
corresponding to alkyl chains. The standard transfer volumes (Δtr
V
φ
0) for all amino acids are positive and increase
with the calcium acetate concentrations and decrease with temperature,
except for l-valine and l-leucine. Volumetric interaction
coefficients of amino acids have been determined using the McMillan–Mayer
equation. Calcium acetate shows a strong dehydration effect on amino
acids over the entire concentration range. All results show a preferential
solvation phenomenon in the mixture due to electrostatic interactions
at the first layer solvation between the charged groups of amino acids
and the inorganic salt.
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