| Abstrakt: |
Organic esters of carbonic acid {dimethyl carbonate (DMC)/diethyl carbonate (DEC)/propylene carbonate (PC)}, in combination with a lactate ester {ethyl lactate (EL)}, with green chemistry characteristics were chosen for the present study of molecular interactions in binary liquid mixtures. Densities ( ρ) and ultrasonic velocities ( U) of the pure solvents and liquid mixtures were measured experimentally over the entire composition range at temperatures (303.15, 308.15, 313.15 and 318.15) K and atmospheric pressure. The experimental data was used to calculate thermodynamic and acoustic parameters $$ V_{\text{m}}^{\text{E}} $$ , $$ \kappa_{S}^{\text{E}} $$ , $$ L_{\text{f}}^{\text{E}} $$ , $$ \bar{V}_{\text{m,1}}^{{}} $$ , $$ \bar{V}_{\text{m,2}}^{{}} $$ , $$ \bar{V}_{\text{m,1}}^{\text{E}} $$ , $$ \bar{V}_{\text{m,2}}^{\text{E}} $$ , $$ \bar{V}_{ 1}^{\text{E,0}} $$ and $$ \bar{V}_{ 2}^{\text{E,0}} $$ and the excess functions were fitted with the Redlich-Kister polynomial equation to obtain the binary solution coefficients and the standard deviations. It was observed that the values of $$ V_{\text{m}}^{\text{E}} $$ , $$ \kappa_{S}^{\text{E}} $$ and $$ L_{\text{f}}^{\text{E}} $$ are positive for the mixtures of (EL + DMC/DEC) and negative for those of (EL + PC) over the entire range of composition and temperature. The positive values of $$ V_{\text{m}}^{\text{E}} $$ , $$ \kappa_{S}^{\text{E}} $$ and $$ L_{\text{f}}^{\text{E}} $$ indicate the action of dispersion forces between the component molecules of (EL + DMC/DEC) mixtures whereas negative values for the mixture (EL + PC) suggest the existence of strong specific interactions between the component molecules, probably resulting from chemical and structural contributions. The excess properties have also been analyzed by using the reduced ( $$ Y^{\text{E}} /x_{1} x_{2} $$ ) excess function approach and the results are found to be in agreement with those from the corresponding $$ Y^{\text{E}} $$ (= $$ V_{\text{m}}^{\text{E}} $$ , $$ \kappa_{S}^{\text{E}} $$ and $$ L_{\text{f}}^{\text{E}} $$ ) values. This is further supported by FTIR spectral analysis. [ABSTRACT FROM AUTHOR] |
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