Measurement of diffusion coefficients of electrolytes by a modified open-ended capillary method

Agar, Jon; Lobo, Victor M.M.

doi:10.1039/f19757101659

Cited by 54 publications

(61 citation statements)

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“…The apparatus assembled for use with the open-ended capillary cell in this laboratory is essentially the same as previously reported [5]. The cell has two vertical capillaries, each closed at one end by a platinum electrode and positioned one above the other with the open ends separated by a distance of about 14 mm.…”

Section: Diffusion Measurementsmentioning

confidence: 96%

“…Experimental conditions were such that the concentration at each of the open ends was equal to the ambient solution value c, that is the physical length of the capillary tube coincided with the diffusion path, such that the boundary conditions described in the literature [5] to solve Fick's second law of diffusion are applicable. As a consequence, the so-called Dl-effect [5] is reduced to negligible proportions.…”

Section: Diffusion Measurementsmentioning

confidence: 99%

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Interactions of vanadates with carbohydrates in aqueous solutions

Ribeiro

Valente

Lobo

et al. 2004

Journal of Molecular Structure

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The interaction between the vanadate ion (VO 3 2 , i.e. vanadium (V)) and the carbohydrates sucrose, glucose and fructose has been studied in aqueous solutions (pH < 6, 298.15 K) using measurements of diffusion coefficients, electrical conductivity, Raman and multinuclear NMR spectroscopy. With sucrose and glucose, indications of hydrolysis of the anion in the absence of the sugars came from a decrease in the diffusion coefficient with increasing concentration. Significant effects on the diffusion coefficients were observed in the presence of sucrose and glucose, suggesting interactions between the carbohydrates and vanadate ion. Support for this came from electrical conductivity measurements, where there were indications of formation of oligomeric species. These were found to depend on the carbohydrate used: confirmation of oligomer formation came from Raman spectroscopy, where it was possible to identify these species, and see their dependence on the particular carbohydrate used. Information on the interactions between the carbohydrates glucose or sucrose and vanadate came from 51 V and 1 H NMR spectroscopy, where the dominant species appeared to be a 2:2 complex with glucose, possessing trigonal bipyramidal centres, whereas with sucrose it is suggested that octahedral species are formed. Studies with fructose were complicated by competing oxidation of this carbohydrate and reduction of vanadium (V). q

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Section: Diffusion Measurementsmentioning

confidence: 96%

Section: Diffusion Measurementsmentioning

confidence: 99%

Interactions of vanadates with carbohydrates in aqueous solutions

Ribeiro

Valente

Lobo

et al. 2004

Journal of Molecular Structure

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“…The experimental diffusion coefficients, D, in aqueous solutions of electrolytes, at 25°C, were collected from Refs. [4,[21][22][23][24][25][26][27][28] and, for two cases (NaClO 4 and NaClO 3 ), measured recently with our technique [19,20]. They were used to calculate the values of a shown in Table 1, assuming the Onsager-Fuoss model Eq.…”

Section: Estimation Of a From Experimental Mean Ionic Activity Coeffimentioning

confidence: 99%

“…The experimental methods that were used to measure mutual differential diffusion coefficients are: conductimetric (uncertainty ± 0.2%) [18][19][20][21][22][23][24][25][26][27][28]; Gouy and Rayleigh interferometry (uncertainty b0.1%) [21]; and Taylor dispersion (uncertainty ± 1-2%) [21]. The experimental diffusion coefficients, D, in aqueous solutions of electrolytes, at 25°C, were collected from Refs.…”

Section: Estimation Of a From Experimental Mean Ionic Activity Coeffimentioning

confidence: 99%

Mean distance of closest approach of ions: Sodium salts in aqueous solutions

Ribeiro

Esteso

Lobo

et al. 2006

Journal of Molecular Liquids

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“…Three experimental methods were used to measure mutual differential diffusion coefficients: conductimetric measurements (uncertainty ± 0.2%) [29][30][31][32][33][34][35][36][37][38][39], Gouy and Rayleigh interferometry (uncertainty b 0.1%) [32], and Taylor dispersion (uncertainty ± 1-2%) [32]. The experimental diffusion coefficients, D, in aqueous solutions of electrolytes, at 25°C, were collected from references [15,[32][33][34][35][36][37][38][39].…”

Section: Estimation Of "A" From Experimental Mean Ionic Activity Coefmentioning

confidence: 99%