Diffusion Velocity and Molecular Weight. I. The Limits of Validity of the Stokes--Einstein Diffusion Equation

Friedman, Leo; Carpenter, Paul

doi:10.1021/ja01876a032

Cited by 22 publications

(12 citation statements)

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“…The results are given in Table 1. D2 values could not be calculated for polyglucose, as no value of its diffusion coefficient in water was available. The diffusion coefficient (at 200 C) of serum albumin was taken as 6-1 x 10-7 cm2/sec (Kekwick, 1938), and that of glucose as 5-9 x 10-6 cm2/sec (Friedman & Carpenter, 1939). A single experiment was also done on the diffusion of serum albumin in water and in a gel made by heating a 0-3 % solution of soluble collagen to 370 C; the values of Dx were almost identical, showing that collagen gel of this concentration has little effect.…”

Section: Diffusion Coefficientsmentioning

confidence: 99%

Effects of hyaluronic acid upon diffusion of solutes and flow of solvent

Ogston¹,

Sherman²

1961

The Journal of Physiology

112

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Section: Diffusion Coefficientsmentioning

confidence: 99%

Effects of hyaluronic acid upon diffusion of solutes and flow of solvent

Ogston¹,

Sherman²

1961

The Journal of Physiology

112

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“…5 However, the Stokes-Einstein equation is based on the assumption of free diffusion, which requires the diffusion coefficient to be determined at infinite dilution 6,7,8,9. It is also known that the diffusion coefficient varies considerably with the concentration of the diffusate thus it is difficult to calculate the exact FW of a species from a single DOSY experiment at a fixed concentration.…”

Section: Introductionmentioning

confidence: 99%

Formula Weight Prediction by Internal Reference Diffusion-Ordered NMR Spectroscopy (DOSY)

et al. 2009

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Formula weight information is important to characterize the composition, aggregation number, and solvation state of reactive intermediates and organometallic complexes. We describe an internal reference correlated DOSY method for calculating the FW of unknown species in different solvents with different concentrations. Examples for both the small molecule (DIPA) and the organometallic complex (aggregate 1) yield excellent correlations. We also found the relative diffusion rate is inversely proportional to the viscosity change of the solution, which is consistent with the theoretical Stokes-Einstein equation. The accuracy of the least square linear prediction r 2 and the percentage difference of FW prediction are directly related to the density change; greater accuracy was observed with decreasing density. We also discuss the guidelines and other factors for successful application of this internal reference correlated DOSY method. This practical method can be conveniently modified and applied to the characterization of other unknown molecules or complexes.

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“…On the basis of the size of the alcohols, this result was expected as the free volume theory would predict. 37,38 This behavior suggests that size rather than intermolecular interaction (hydrogen bonds in particular) dominates the diffusion process. 23 Here, it was expected that methanol would diffuse more slowly as it has the highest ability to form hydrogen bonds.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Inverse Gas Chromatography Study of the Permeability of Aroma through Hydroxypropyl Xylan Films

Bayati

Boluk

Choi

2015

ACS Sustainable Chem. Eng.

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Inverse gas chromatography (IGC) was used to study the permeability of a series of aromas through neat hydroxypropyl xylan (HPX) film and HPX films containing sorbitol, a commonly used food grade plasticizer, and cellulose nanocrystal (CNC), a nanosized filler. The aroma used included methanol, ethanol, propanol, and butanol. Also, their solubility and diffusion coefficients at infinite dilution were measured over the temperature range 120−160 °C, and the corresponding permeability coefficients were calculated. It was observed that the alcohols exhibited lower solubility (3 orders of magnitude) and diffusivity (2−3 orders of magnitude) than those of water in the neat HPX film. Solubility coefficient showed a minimum over the range of the molecular weight of the aforementioned alcohols. However, the diffusion coefficient decreased monotonically with increasing the alcohol's molecular weight. Adding sorbitol (40 wt %) decreased solubility coefficients slightly but increased diffusion coefficients by about 1 order of magnitude. However, replacing 5 wt % of sorbitol by CNC while maintaining the total additive concentration at 40 wt % did not alter the solubility coefficients much but decreased diffusion coefficients by approximately half of the values of the HPX film containing 40 wt % sorbitol. Permeability, a quantity signifying the combined effect of solubility and diffusivity, was observed to decrease with increasing the alcohol's molecular weight. This implies that diffusivity controls the permeability of the alcohols at high molecular weights. As expected, sorbitol increases while CNC decreases permeability. However, effects of additives are stronger for methanol and ethanol than for propanol and butanol. Temperature also exerts stronger effects for methanol and ethanol than for propanol and butanol. The above observation is likely due to the differences in the abilities of the low and high molecular weight alcohols to form hydrogen bonds with HPX, sorbitol, and CNC.

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Diffusion Velocity and Molecular Weight. I. The Limits of Validity of the Stokes--Einstein Diffusion Equation

Cited by 22 publications

References 0 publications

Effects of hyaluronic acid upon diffusion of solutes and flow of solvent

Effects of hyaluronic acid upon diffusion of solutes and flow of solvent

Formula Weight Prediction by Internal Reference Diffusion-Ordered NMR Spectroscopy (DOSY)

Inverse Gas Chromatography Study of the Permeability of Aroma through Hydroxypropyl Xylan Films

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