The Effect of Ions on the Self-Diffusion of Water. I. Concentration Dependence

McCall, David W.; Douglass, D. C.

doi:10.1021/j100890a034

Cited by 167 publications

(88 citation statements)

References 6 publications

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“…The velocity of the reaction probably depended on these parameters. The hydration numbers of Li + and OH − , around 10 and 12, respectively, indicated that water increased the self-diffusion rate in aqueous LiOH (12). Moreover, the molar ratio of TAG/LiOH supported a stoichiometric reaction.…”

Section: Resultsmentioning

confidence: 91%

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Fourier‐transform infrared spectra of fatty acid salts—Kinetics of high‐oleic sunflower oil saponification

Poulenat

Sentenac

Mouloungui

2003

J Surfact & Detergents

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Sodium, lithium, and calcium soaps obtained by saponification of high-oleic sunflower oil were studied by Fourier-transform infrared spectroscopy. Spectra of crude mixtures containing soap, glycerin, residual alkali, and triacylglycerols were compared to those of pure soaps obtained from fatty acids. The infrared spectra of crude soaps showed the same characteristic bands as pure ones. The absorption bands of asymmetric (ω 2 ) and symmetric (ω 1 ) stretching vibrations of the carboxylate group indicated that the metal-oxygen bonds of these soaps had an ionic character whose strength differed from one cationic counterion to another. Once the characteristic absorption bands of the soaps were assigned, a kinetics study of saponification was performed. Saponification by sodium, anhydrous lithium, and calcium hydroxides was an autocatalytic reaction, characterized by an Sshaped kinetics curve, whereas saponification by aqueous lithium hydroxide was stoichiometric. The structure of the metal-oxygen bond played a role in the kinetic mechanisms.Paper no. S1345 in JSD 6, 305-310 (October 2003).KEY WORDS: Alkaline-earth soaps, alkaline soaps, higholeic sunflower oil, infrared spectroscopy, kinetics of saponification, saponification.Among all the oleaginous plants having a high-oleic acid content, only sunflower is grown on a large scale in open fields throughout the world. The high-oleic sunflower oil (HOSO) obtained from these plants is available for food uses as well as for industrial ones. The properties of HOSO are linked to their high content of oleic acid (18:1): stability vs. oxidation, fluidity, and a monounsaturated substrate. Its vegetable origin is a commercial asset for many applications, commercial as well as technical. Soap manufacture from vegetable oils is quite well known and used, but few quantitative studies have been done on the saponification reaction itself. Soaps with a high-oleic acid content once were manufactured from tallow, but because of the spread of the bovine spongiform encephalopathy and the importance of oleaginous plant farming in the northern hemisphere, e.g., sunflower cultivation, a more accurate study of saponification is now needed to produce alkaline or alkaline-earth soaps easily from vegetable oils.Study of the infrared spectra of soaps allows us to compare crude soaps, obtained from the saponification of triacylglycerols (TAG) of vegetable oils, with those obtained by more traditional means [the neutralization of fatty acids (1,2), a double decomposition reaction between an alkaline soap and a metallic salt (3), or the fusion of fatty acids (3)]. The choice of metallic counterion in the soap is essential; physiochemical properties of the final product, and thus its uses, depend on it. Moreover, Fourier-transform infrared (FTIR) spectroscopy enables one to compare the kinetics of saponification of HOSO based on the metallic hydroxide used: sodium, lithium, or calcium hydroxide. The aim of this study was thus to characterize crude soaps and then to evaluate the kinetics of the sapo...

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Section: Resultsmentioning

confidence: 91%

“…Owing to the effect of ionic species (e.g., Li + , OH − ) on the self-diffusion of water and the ionic self-diffusion concentration, water helped to put the reactants in contact and enhanced the kinetics of TAG saponification in aqueous LiOH (12). The velocity of the reaction probably depended on these parameters.…”

Section: Resultsmentioning

confidence: 99%

Fourier‐transform infrared spectra of fatty acid salts—Kinetics of high‐oleic sunflower oil saponification

Poulenat

Sentenac

Mouloungui

2003

J Surfact & Detergents

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“…The Do value for 3H (as HTO) at 23~ was taken to be 2450 #m2/s (McCall and Douglass 1965); and the values for the other diffusants were obtained from Li and Gregory (1974) and calculated for 23~ from,…”

Section: Diffusantsmentioning

confidence: 99%

Surface Diffusion: Is It an Important Transport Mechanism in Compacted Clays?

Oscarson

1994

Clays and clay miner.

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Abstract--Surface diffusion, or migration within the electrical double layer next to mineral surfaces, is often invoked as a significant contributor to the overall diffusion coefficient in compacted clays, particularly where model predictions underestimate measured diffusion coefficients. The potential for surface diffusion of Sr 2 § Ca 2+ and Na + on three clays compacted to dry bulk densities of 1.25 and 1.60 Mg/m 3 was examined. The clays were a bentonite, an illite/smectite, and a glacial lake clay (composed mainly of smectite, illite, kaolinite and quartz). The clays were saturated with a Na-Ca-Cl-dominated synthetic groundwater solution with an effective ionic strength of 220 mol/m 3. Total intrinsic diffusion coefficients for the cations were determined from their steady-state flux through compacted clays, and apparent diffusion coefficients were obtained from the time-lag technique. Models of diffusive transport in compacted clays, based only on diffusion in the pore solution, adequately described the diffusion data for all clays and diffusants, and there was no need to invoke other transport mechanisms, like surface diffusion. The data indicate that surface diffusion is not a significant transport mechanism in compacted clays at least to a clay density of 1.60 Mg/m 3.

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“…technique has yielded a great deal of information about concentrated solutions of electrolytes. Most of these results have been obtained from studies of the proton magnetic resonance of the solvent water (1)(2)(3)(4)(5). Comparatively few results have been obtained by observing the resonance of a nucleus within the electrolyte (6).…”

Section: Introductionmentioning

confidence: 99%

Solvation of sodium ions studied by ²³Na nuclear magnetic resonance

Bloor¹,

Kidd²

1968

Can. J. Chem.

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The 23Na chemical shifts, extrapolated to infinite dilution, of solutions containing sodium iodide dissolved in 14 different oxygen or nitrogen donor organic solvents have been determined. The observed range of chemical shifts can be successfully related to changes in the paramagnetic term of the general nuclear screening equation. A fair correlation between the magnitude of the paramagnetic termand the Lewis basicity of the solvent has been drawn. Those solvents showing anomalous behaviorare theones for which large magnetic anisotropies are to be expected. The 23Na chemical shifts for two mixed solvent systems containing sodium iodide have been obtained, and these support the conclusion that preferential solvation of the sodium ion occurs.

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The Effect of Ions on the Self-Diffusion of Water. I. Concentration Dependence

Cited by 167 publications

References 6 publications

Fourier‐transform infrared spectra of fatty acid salts—Kinetics of high‐oleic sunflower oil saponification

Fourier‐transform infrared spectra of fatty acid salts—Kinetics of high‐oleic sunflower oil saponification

Surface Diffusion: Is It an Important Transport Mechanism in Compacted Clays?

Solvation of sodium ions studied by ²³Na nuclear magnetic resonance

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The Effect of Ions on the Self-Diffusion of Water. I. Concentration Dependence

Cited by 167 publications

References 6 publications

Fourier‐transform infrared spectra of fatty acid salts—Kinetics of high‐oleic sunflower oil saponification

Fourier‐transform infrared spectra of fatty acid salts—Kinetics of high‐oleic sunflower oil saponification

Surface Diffusion: Is It an Important Transport Mechanism in Compacted Clays?

Solvation of sodium ions studied by 23Na nuclear magnetic resonance

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Product

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Solvation of sodium ions studied by ²³Na nuclear magnetic resonance