Diffusion measurements in liquids by the Gouy method

Thomas, W. J.; Furzer, I. A.

doi:10.1016/0009-2509(62)80023-2

Cited by 62 publications

(15 citation statements)

References 9 publications

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“…Two new cells were designed for use in conjunction with the diffusiometer. One was a boundary-sharpening, flowing-junction cell similar to that used by Thomas and Furzer ( 1962); the other was designed for temperature-jump initiation of the diffusion process.…”

Section: Methodsmentioning

confidence: 99%

“…In a highly nonideal system such as this, the measured diffusion coefficients are not expected to be as accurate as those for the aqueous sucrose test system, but the maximum uncertainty in the results reported here is less than 10% as determined from worst-possible-case analysis. The major source of error is the uncertainty in the fractional portion of the fringe analysis as determined with the iterative scheme of Thomas and Furzer ( 1962). Additional errors include imperfect initial interface formation, moisture, and the assumption of concentration-indepen- dent diffusion coefficients required by the Gouy analysis procedure; see Figure 4.…”

Section: Measured Values For the Binodal Curve Are Listed Inmentioning

confidence: 99%

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The mutual diffusion coefficient of methanol–n‐hexane near the consolute point

Clark¹,

Rowley²

1986

AIChE Journal

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The composition and temperature dependence of the mutual diffusion coefficient near the liquid-liquid critical point of methanol-n-hexane mixtures has been determined by Gouy interferometry. The critical exponent was found to be 0.685. Constant-temperature extrapolation to zero diff usivity located the spinodal curve. Spinodal loci calculated from the NRTL model are inconsistent with the experimentally determined values. W. M. Clark and R. L. Rowley Department of Chemical EngineeringRice University Houston, TX 7725 1 SCOPEMutual diffusion coefficients can be separated into two parts: a mobility or Onsager term and a thermodynamic factor. The mathematical criterion, which defines the spinodal curve and demarcates the unstable region interior to the equilibrium coexistence curve, can be expressed as the loci of points where the thermodynamic factor is identically zero. Classical and light-scattering experiments have shown that the diffusion coefficient goes to zero as the temperature approaches the liquid-liquid critical point at constant critical composition. Although Skripov et al. (1980) concluded that the diffusion coefficient for the methanoln-hexane system vanished at the same rate as the thermodynamic factor, indicating a finite Onsager term, it has been fairly well established by studies on other systems that the Onsager coefficient actually diverges as the critical point is approached. One purpose of this study was to determine the critical exponent in the methanol-n-hexane system by a series of temperaturejump-initiated diffusion experiments in a Gouy interferometer. The diffusion critical exponent has significant implications in terms of universality and scaling theories.The second purpose was to use diffusion coefficient measurements to determine the spinodal curve. Since the diffusion coefficient must be zero at the spinodal, extrapolation of measured diffusivities to zero could be used to determine its location. No methods have heretofore been able to provide spinodal information in liquid-liquid phase-splitting systems. Classical equilibrium studies provide only coexistence information. Nevertheless, the location of the spinodal curve could be extremely valuable in developing and testing liquid mixture models for the Gibbs free energy since it is related to the second derivative with respect to composition, as shown in Eq. 7. Generally, liquid-mixture model parameters are fitted from the solubility or equilibrium concentration information. No other data have been available to test the model at other compositions at the same temperature. The spinodal criterion on the other hand provides additional restrictions that a satisfactory and consistent liquid-mixture model must satisfy. CONCLUSIONS AND SIGNIFICANCEDiffusion coefficients were measured in methanol-nhexane mixtures as a function of temperature along the critical composition in a temperature-jump cell using a Gouy interferometer. The critical exponent was found to be 0.685, in good agreement with previous studies on other systems, indicating that...

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Section: Methodsmentioning

confidence: 99%

Section: Measured Values For the Binodal Curve Are Listed Inmentioning

confidence: 99%

The mutual diffusion coefficient of methanol–n‐hexane near the consolute point

Clark¹,

Rowley²

1986

AIChE Journal

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“…The diffusion coefficient of MEA in aqueous solution is known to be concentration sensitive and the data of Ibrahim and Kuloor (1962) and Thomas and Furzer (1962) were used to account for this. The diffusivity of COz in MEA was assumed to be affected by amine concentration in the same way as amine diffusivity, while temperature effects were described by the correlation of Barrett (1958).…”

Section: Kolamentioning

confidence: 99%

“…For example, the viscosity of MEA solutions at 25°C rises by nearly a factor of 2.5 from infinite dilution to 5 kmol/m3 (Thomas and Furzer, 1962;Union Carbide, 1969). These viscosity increases simultaneously cause a reduction in the diffusion coefficients of the dissolved species and both effects combine to force large decreases in kE.…”

Section: Amine Concentrationmentioning

confidence: 99%

Stripping of carbon dioxide from monoethanolamine solutions in a packed column

Weiland

Rawal²,

Rice

1982

AIChE Journal

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A procedure using only fundamental physico‐chemical data is developed for the design and analysis of packed columns used for solvent recovery in gas purification processes involving chemical reaction. The results of 173 experiments on the mass transfer performance of a pilot‐scale regenerator stripping CO2 from loaded monoethanolamine solutions are reported and compared with model predictions. Anomolous responses of the overall mass transfer coefficient to changes in process conditions are observed and explained by the process model which is found to predict correctly both the magnitude of the coefficient and its response.

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“…The diffusivities of carbon dioxide and RNHz in the liquid phases DA and DB were given by Clarke (1964) and Thomas and Furzer (1962), respectively. The value of the reaction rate constant was taken as 8 400 1/ (g-mole) (s), which was derived from the liquid jet data under presumably pseudo first-order reaction.…”

Section: Resultsmentioning

confidence: 99%