Henry’s law constant for environmentally significant compounds

Many nonvolatile organic compounds, e.g., polyaromatic hydrocarbons (PAHs), are readily stripped during aerobic biodegradation. This is because of the high infinite dilution activity coefficient resulting from forces generated by the water-organic interactions at the molecular level. Several models have been proposed for air-stripping based on the Henry’s law constant. By definition, the Henry’s law constant is the infinite dilution activity coefficient multiplied by the pure component vapor pressure. In this article, a gas saturation technique was used to measure the very low vapor pressures exhibited by these nonvolatile compounds. Literature values of other PAHs have been tabulated and are presented. For determining infinite dilution activity coefficients, a differential ebulliometery apparatus has been constructed. In this technique, the boiling point difference between pure water and a water-organic solution is measured very precisely. Thermodynamics is then used to calculate the infinite dilution activity coefficient. The method’s accuracy has been tested using the phenol-water system.     

The determination of activity coefficients at infinite dilution using g.l.c. for hydrocarbons in furfural at T=278.15 K and T=298.15 K

The activity coefficients at infinite dilution for some alkanes, cycloalkanes, alkenes, alkynes and benzene in furfural have been determined by g.l.c. at T=278.15 K and T=298.15 K. The volatility of the solvent furfural, although low, was taken into account. The method used is an alternative to the pre-saturation method. The results have been used to predict the potential for furfural as a solvent in separating aromatic compounds from aliphatic compounds and other hydrocarbons using extractive distillation. The excess enthalpies of mixing at infinite dilution have also been calculated.     

Accurate measurements of thermodynamic properties of solutes in ionic liquids using inverse gas chromatography

Activity coefficients at infinite dilution of 29 organic compounds in two room temperature ionic liquids were determined using inverse gas chromatography. The measurements were carried out at different temperatures between 323.15 and 343.15K. To establish the influence of concurrent retention mechanisms on the accuracy of activity coefficients at infinite dilution for 1-butyl-3-methylimidazolium octyl sulfate and 1-ethyl-3-methylimidazolium tosylate, phase loading studies of the net retention volume per gram of packing as a function of the percent phase loading were used. It is shown that most of the solutes are retained largely by partition with a small contribution from adsorption on 1-butyl-3-methylimidazolium octyl sulfate and that the n-alkanes are retained predominantly by interfacial adsorption on 1-ethyl-3-methylimidazolium tosylate.     

Activity coefficients at infinite dilution of organic compounds in 1-(meth)acryloyloxyalkyl-3-methylimidazolium bromide using inverse gas chromatography

Activity coefficients at infinite dilution, gammainfinity, of organic compounds in two new room-temperature ionic liquids (n-methacryloyloxyhexyl-N-methylimidazolium bromide (C10H17O2MIM)(Br) at 313.15 and 323.15 K and n-acryloyloxypropyl-N-methylimidazolium bromide(C6H11O2MIM)(Br)) were determined using inverse gas chromatography. Phase loading studies of the net retention volume per gram of packing as a function of the percent phase loading were used to estimate the influence of concurrent retention mechanisms on the accuracy of activity coefficients at infinite dilution of solutes in both ionic liquids. It was found that most of the solutes were retained largely by partition with a small contribution from adsorption and that n-alkanes were retained predominantly by interfacial adsorption on ionic liquids studied in this work. The solvation characteristics of the two ionic liquids were evaluated using the Abraham solvation parameter model.