Interactions of vanadates with carbohydrates in aqueous solutions

Abstract

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

Aggregation and micellization of sodium dodecyl sulfate in the presence of Ce(III) at different temperatures: A conductometric study

“…A Shedlovsky-type conductance cell, with a cell constant of approximately 0.0802 cm −1 was used in the measurements [20]. Solutions were always studied within 12 h after preparation.…”

“…The cmc ap was calculated using the same method described above to calculate the cac 1 . The degree of micellar counterion dissociation (α), for aqueous CeCl 3 /SDS solutions, was calculated from the ratio between the slopes of the postmicellar and premicellar regions, in the plots of κ = f (c) [20].…”

The interaction of long chain sodium carboxylates and sodium dodecylsulfate with lead(II) ions in aqueous solutions

“…Electrical conductance measurements were carried out with a Wayne-Kerr model 4265 automatic LCR meter at 1 kHz, through recording of solution electrical resistances, measured by a conductivity cell with a constant of 0.1178 cm −1 (uncertainty 0.02 %) [44]. The cell constant was determined from electrical resistance measurements with KCl (reagent grade, recrystallized, and dried) using the procedure and data of Barthel et al [45].…”

Diffusion coefficients and electrical conductivities for calcium chloride aqueous solutions at 298.15K and 310.15K

“…This method, profusely described in previous publications by this group [4,5,9,10], has given accurate results for a wide variety of electrolytes [1].…”

“…In the present paper, experimental data in the concentration range from 0.005 mol dm −3 to 0.1 mol dm −3 at 298.15 K and 310.15 K, are reported. To obtain these, an open-ended conductimetric capillary cell, which has been proved to give precise and accurate results [1][2][3][4][5], was used. The results obtained are analysed using both the Onsager-Fuoss [6] and Gordon [7] models to elucidate if either the ion pairs that this calcium salt originates in aqueous solutions, or the viscosity of the solution, affect their diffusion in the solvent.…”