Measurement of solution thermodynamic properties of methylsoyate/solvent systems by inverse gas chromatography.

摘要

The thrust of this study was to evaluate certain thermodynamic properties of methylsoyate. Methylsoyate, produced via a variety of chemical processes, has commercial application as a safe, green solvent and as a bio-based fuel. It is a mixture of fatty acid methyl esters and other organic chemicals. Inverse Gas Chromatography (IGC) was chosen as the evaluation method. IGC "inverts" the structure of a normal gas chromatographic column, using the target chemical, methylsoyate, as the liquid or stationary phase of the column. Different test solvents, "probes" were then injected into the column and the retention properties were measured. Solution thermodynamic properties of the methylsoyate/probe system were then calculated from the retention properties. Nineteen probes representing five general classes of solvents were used. Temperatures were varied in the range of 50--85 C.;Regression analysis was applied to the results of the calculations and from the curve-fitted parameters, tables of properties versus temperature were generated. The molar-based activity coefficients for the probe methanol were compared to values obtained by other researchers by other measurement techniques. The values were all in close agreement. The Hildebrand solubility parameter for methylsoyate was compared to that calculated for one of its components by a group contribution method and the values were found to be in good agreement.;Properties of the methylsoyate studied included the specific retention volume, the weight-based activity coefficient, the molar-based activity coefficient, the Henry's law constant, the liquid-gas partition coefficient, the partial molar enthalpies of mixing and solution, and the Hildebrand solubility parameter. All properties were evaluated at near infinite dilution by the expedient of making very small sample injections.