Heat of solution of extractants in hydrocarbon solvents

. Can. J. Chem. 57, 1218 (1979).The adsorption of tri-n-butylphosphate (TBP) from n-dodecane to the n-dodecane-water interface has been studied as a function of TBP mole fraction up to 2.7 x in the n-dodecane, and as a function of temperature from 293.15 K to 308.15 K. Free energies of adsorption were calculated from the results at low TBP mole fractions, where the surface pressures were linear with mole fraction. They were in the range -36.1 to -35.6 kJ/rnol. The enthalpy of adsorption, determined from the variation of the free energies of adsorption with temperature, was -45.4 kJ/mol.Several equations of state based on two-dimensional gas laws were applied to the results. [Traduit par le journal]

Section: Free Energies and Enthalpies Of Adsorptionmentioning

confidence: 99%

The adsorption of tri-n-butylphosphate at the n-dodecane–water interface

Sagert¹,

Lee²,

Quinn³

1979

“…It would be desirable to compare the standard enthalpies of transfer obtained here with those calculated from calorimetric data, since the enthalpy of transfer is simply the difference between the enthalpies of solution in the two phases. The enthalpy of solution of TBP in benzene was determined by Kertes et al (5) to be -1.7 kJ/mol. However, the heat of solution of TBP in water has not been measured because of the low solubility of TBP in water.…”

Section: Thermodynamics Of Transfermentioning

confidence: 99%

“…However, the overall process must be much more complicated than simply breaking hydrogen bonds, since complexing of TBP with benzene is also involved. It seems that complexing of TBP with benzene begins to occur (5)(6)(7) at the same time as the hydrogen bonds with water are broken, when the TBP moves from water to the interface. On moving from the interface into benzene, these two processes are almost balanced.…”

Section: Thermodyrzamics Of Adsorptionmentioning

confidence: 99%

The adsorption of tri-N-butylphosphate at the benzene–water interface

Sagert¹,

Lee²,

Quinn³

1982

Adsorption of tri-n-butylphosphate (TBP) at the benzene–water interface was studied as a function of the TBP mole fraction in benzene up to 0.018 and at temperatures from 9 to 29 °C. The extent of adsorption was calculated from interfacial tension data obtained by the drop-volume technique. Standard free energies of adsorption from benzene ranged from −20.9 kJ/mol at 9 °C to −22.5 kJ/mol at 29 °C, giving a standard enthalpy of adsorption of +2.5 kJ/mol. Thus the strong adsorption occurs because of entropy changes. Distribution coefficients for the partition of TBP between benzene and water were measured by gas chromatography, and standard free energies of adsorption from water were derived. They ranged from −44.8 kJ/mol at 9 °C to −51.1 kJ/mol at 29 °C, with standard enthalpies of adsorption ranging from 74 to 15 kJ/mol over the same temperature range.Results at higher mole fractions were fitted to various equations of state, after using vapor pressure osmometry (at 37 °C) to determine that activity corrections were small. The Schofield–Rideal equation described the results adequately, with A0 close to 1.0 nm2 and/close to 1.0 at lower temperatures. These values imply that lateral repulsion between TBP molecules in the adsorbed layer is minimal.

“…TBP have been measured in hexane and dodecane Tributylphosphate has been widely used in ex- (7) and enthalpies of Solution of TPP are available traction processes for separating the components for water (61, and i-octane (8)-The distribution of irradiated nuclear fuel (1). As part of a program TEP and TMP between water and to study the interfacial properties relevant to such dodecane have not been measured-For both solsolvent extraction systems, we have studied the utes good calorimetric data on enthalpies of soluof trimethylphosphate (TMP), triethyl-tion in Water (5) are available but little is known phosphate (TEP), t r i p r o p y~p~o s p~a t e (~p p ) , and about their enthalpies of solution in alkanes.…”

Section: Introductionmentioning

confidence: 99%

“…[6] we obtain eq. [7] where K, is, of course, the equilibrium constant for dimerization as given in eq. [6].…”

Section: Introductionmentioning

confidence: 99%

The distribution of trialkylphosphates between dodecane and water

Sagert¹,

Lee²

1980

). The distribution of the four lower trialkylphosphates, triethyl, trimethyl, tripropyl, and tributylphosphates, between dodecane and water has been measured a s a function of temperature between 293.15 K and 3 13.15 K , and as a function of trialkylphosphate concentration at concentrations below 0.1 mol/dm3. From these results, the thermodynamic functions associated with the transfer of each of these trialkylphosphates from water to dodecane were calculated. With the exception of trimethylphosphate, free energies of transfer changed by -3.5 kJ/mol for each methylene group added to the solute. The enthalpies of transfer for all the trialkylphosphates were in the range of 26 to 30 kJ/mol, so that most of the differences in the free energies of transfer arise from entropic differences.Dimerization constants for the trialkylphosphates in dodecane were consistent with those available in the literature. Chem. 58,1463Chem. 58, (1980. On a mesure la distribution des 4 trialkylphosphates inferieurs, tritthyl-, trimethyl-, tripropyl-et tributylphosphates, entre le dodecane et I'eau, en fonction de la temperature entre 293.15 et 3 13.15 K et en fonction de laconcentration de trialkylphosphate pour des concentrations inferieurs a 0.1 mol/dm3. A partir de ces resultats, on a calcule les fonctions thermodynamiques associees au transfert de chacun de ces trialkylphosphates de I'eau au docecane. A I'exception du cas du trimethylphosphate, I'addition d'un groupe methylenique au solutt provoque une variation de -3.5 kJ1mol dans I'tnergie libre de transfert. Les enthalpies de transfert de tous les trialkylphosphates sont de I'ordre de 26 i 30 kJ1mol de telle sorte que la plupart des differences des energies libres de transfert proviennent de differences entropiques.Les constantes de dimtrisation des trialkylphosphates dans le dodecane sont en accord avec celles rapportees dans la litterature.[Traduit par le journal] IntroductionTBP have been measured in hexane and dodecane Tributylphosphate has been widely used in ex-(7) and enthalpies of Solution of TPP are available traction processes for separating the components for water (61, and i-octane (8)-The distribution of irradiated nuclear fuel (1). As part of a program TEP and TMP between water and to study the interfacial properties relevant to such dodecane have not been measured-For both solsolvent extraction systems, we have studied the utes good calorimetric data on enthalpies of soluof trimethylphosphate (TMP), triethyl-tion in Water (5) are available but little is known phosphate (TEP), t r i p r o p y~p~o s p~a t e (~p p ) , and about their enthalpies of solution in alkanes. The tributylphosphate (TBP) (2) at the dodecane-water only data available are for TEPin i-octane (8)-interface. In order to interpret these adsorption It therefore seemed appropriate to make a cornresults, it is necessary to have a good ther-plete study of the distribution ratios of the four rnodynamic description of the process in which lower trialkylphosphates at Solute concentrations solute is trans...