Loren G. Hepler

Densities, excess molar volumes, and partial molar volumes for binary mixtures of water with monoethanolamine, diethanolamine, and triethanolamine from 25 to 80°C

We have measured densities of binary mixtures of water with monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) over the full range of compositions and over the temperature range from 25 to 80°C. Results of these measurements have been used in calculating excess molar volumes and partial molar volumes. Knowledge of the volumetric properties of these mixtures is useful in connection with industrial treatment of acidic gases; derived excess molar volumes and partial molar volumes can be used as a basis for understanding some of the molecular interactions in water-organic mixtures.

Volumetric properties of aqueous solutions of monoethanolamine, mono- and dimethylethanolamines at temperatures from 5 to 80 °C. I

Abstract Densities of aqueous binary mixtures of monoethanolamine, monomethylethanolamine and dimethylethanolamine were measured over the whole range of compositions at temperatures varying from 5 to 80xa0°C. The density of monoethanolamine+water mixtures shows a maximum (x2=0.43 at 5xa0°C). The density behavior of monoethanolamine+water and dimethylethanolamine+water mixtures is different from the monoethanolamine+water system. The composition dependence of the densities of these two mixtures was classified in two distinct zones. This separation line occurs at x2=0.20 for monoethanolamine+water and x2=0.12 for the dimethylethanolamine+water system. In the low concentration zone, the density values exhibit a minimum and a maximum at increasing ethanolamine concentration, while in the high concentration zone, the density values approach the density of the pure alkanolamine in a monotonic fashion. The excess molar volume of these mixtures is dependent on the structure of the ethanolamines: V E (monoethanolamine + water ) E ( monoethanolamine + water ) E ( dimethylethanolamine + water ).

Thermal and volumetric properties of chloroform+benzene mixtures and the ideal associated solution model of complex formation

In the ideal associated solution model, activity coefficients of all species (labelled A, B, and AB here) at equilibrium are taken to be unity at all compositions and temperatures. We have applied this model to an analysis of thermodynamic properties (vapor pressures, excess enthalpies, partial molar enthalpies of solution, excess heat capacities, and excess volumes) of the chloroform+benzene system in terms of K, ΔHθ, ΔCpθ, and ΔVθ for the equilibrium represented by A+B=AB. It is demonstrated that there is reasonably good consistency between this simple model and all of the thermodynamic data, which shows that the model is realistic enough to be useful in assessing the properties of the not-very-stable AB complex in the chloroform+benzene system. New thermal (partial molar enthalpies of solution and excess heat capacities) and volumetric properties of the chloroform+benzene system have been measured, with results presented here.

Volumetric properties of aqueous solutions of mono, and diethylethanolamines at temperatures from 5 to 80 °C II

Abstract Densities of aqueous solutions of monoethylethanolamine (MEEA) and diethylethanolamine (DEEA) were measured over the whole range of concentrations at temperatures from 5 to 80xa0°C. Densities of these systems show different behavior at both lower and higher concentration of ethanolamine. This behavior was classified into two zones: at x 2 =0.12 for (MEEA+water) and at x 2 =0.04 for (DEEA+water) mixtures. It is found that in the low concentration zone the effect of alkyl groups could be shown as: ue5f8 CH 3 >ue5f8 C 2 H 5 >2(ue5f8 CH 3 )>2(ue5f8 C 2 H 5 ) The excess molar volumes and excess molar enthalpies of (alkylethanolamine+water) mixtures show similar dependence on the size of the alkyl group present in the alkyethanolamines. The excess molar volumes have the most negative value for the (ethylethanolamine+water) system, while the excess molar enthalpies of the (MEEA+water) system have the more negative value.

Apparent molar heat capacities and volumes of aqueous HClO4, HNO3, (CH3)4NOH and K2SO4 at 298.15 K

Abstract Apparent molar heat capacities and volumes of HClO 4 (aq), HNO 3 (aq), (CH 3 ) 4 NOH(aq) and K 2 SO 4 (aq) have been determined at 298.15 K. Infinite dilution standard state partial molar heat capacities and volumes have been calculated from these data. We recommend revised values for the conventional ionic partial molar heat capacities and volumes of ClO 4 − (aq), NO 3 − (aq) and SO 4 2− (aq).

Thermal and volumetric properties of chloroform + dimethylsulfoxide: Thermodynamic analysis using the ideal associated solution model

We have made new measurements of partial molar enthalpies of solution, excess heat capacities, and excess volumes of mixtures of chloroform and dimethylsulfoxide. In combination with published vapor pressures and excess enthalpies the results of these measurements have been analyzed within the context of the ideal associated solution model to yield ΔCpϑ and ΔVϑ for the formation of AB and A2B complexes. It is shown that the ideal associated solution model is consistent with all of the available thermodynamic data for this system, indicating that nearly all of the deviations of this system from ideal solution behavior can be accounted for in terms of chemical interactions of the two components.

Thermodynamic parameters for pentachlorophenol sorption on montmorillonite in aqueous suspensions

Abstract Knowledge of physical, chemical, and biological processes affecting organic contaminants in soils is essential to develop remediation technologies and assess risk from alternative technologies. Of these processes, sorption is one of the most important in soils because it regulates other processes and hence fate, transport and removal of contaminants. The objectives of this research are: 1) to evaluate the thermodynamic parameters and bonding strength for pentachlorophenol (PCP) onto montmorillonite at ionic strengths from 0 to 0.3 molal; and, 2) to test the hypotheses that adsorption is through positive ion pair formation (e.g. CaPCP+), and chemical bonding of phenolate. Calorimetry, Gas-liquid chromatography, Fourier transform infrared spectroscopy, and X-ray diffraction were used in the experiment. The adsorption of PCP onto montmorillonite was strongly influenced by the type of cations and the ionic strength. PCP molecules were mainly adsorbed on the edge of montmorillonite. The standard enthalpy changes (ΔH°) of PCP adsorption on Ca-montmorillonite ranged from −24.3 to −38.0 kJ/mol and were most negative at 0.03 molal solution ion concentration, as was ΔG° which ranged from −15.4 to −17.6 kJ/mol, and ΔS° which fell between −29.9 and −68.4 J/K mol. The highest value of lnKO was 7.11, and was obtained at 0.03 molal. Our experimental results are consistent with the above hypotheses concerning adsorption, and multiple mechanisms of adsorption (Coulombic interaction, physi and chemisorption) have been inferred.

Liquid fuels from co-processing coal with bitumen or heavy oil: a review

ABSTRACT Coal, bitumen and heavy oil( and various pitches, resids, etc. ) are similar in that they require more substantial treatment than does conventional light oil to yield useful liquid fuels. Here we provide a brief and selective review of technologies for liquefying coal, followed by consideration of co-processing coal with bitumen/heavy oil. Such co-processing may be considered as use of bitumen/heavy oil as a solvent and/or hydrogen donor In liquefaction of coal, or as the use of coal to aid upgrading bitumen/heavy oil.

The enthalpies of dilution of aqueous organic acids: oxalic acid and citric acid at 298.15 K

Abstract Molar enthalpies of dilution of oxalic acid and citric acid in water at 298.15 K have been measured. They cover the entire range of molalities, up to 1.1827 mol·kg−1 for oxalic acid and 7.2307 mol·kg−1 for citric acid.

CALORIMETRIC INVESTIGATION OF ADSORPTION OF AN AQUEOUS METACHROMIC DYE (CRYSTAL-VIOLET) ON MONTMORILLONITE *

Crystal-violet is a cationic dye that exhibits metachromasy in aqueous solutions and when adsorbed on various solids; the changes in the absorption spectrum of the dye permit identification of monomeric, dimeric, and polymeric species and can also help in distinguishing between several different kinds of dye-adsorbent interactions. This paper reports the results of calorimetric measurements of enthalpies of adsorption of aqueous crystal-violet on to eight different cationic (Li+ K+, Cs+, Mg2+ Ca2+ Ba2+ Cd2+ and Al3+) montmorillonite clays.