Some Transport Properties of γ-Cyclodextrin Aqueous Solutions at (298.15 and 310.15) K

Abstract

Values of binary mutual diffusion (interdiffusion) coefficients, obtained by using the Taylor dispersion method, for aqueous solutions of γ-cyclodextrin in the concentration range from (0.002 to 0.010) mol · dm -3 and temperatures (298.15 and 310.15) K are reported. From these experimental results, the hydrodynamic radius values for the γ-cyclodextrin are estimated. Also, the measured diffusion coefficients are used with both Hartley's and Gordon's equations to estimate activity coefficients for aqueous γ-cyclodextrin. These studies are complemented by some density and viscosity measurements, carried out at the same range of concentrations and temperatures. The effect of both the viscosity of the medium and the formation of γ-cyclodextrin dimers on the estimated hydrodynamic radius is discussed.

Interaction between copper chloride and caffeine as seen by diffusion at 25°C and 37°C

“…Good reproducibility was observed, as seen by the small standard deviations of the mean, S Dav . Previous papers (Ribeiro, Leaist, et al, 2006;Ribeiro et al, 2008) reporting data obtained with this technique have shown that the error limits of our results should be close to the imprecision, therefore, giving an experimental uncertainty of 1-3%.…”

Aggregation of Cyclodextrins: Fundamental Issues and Applications

“…The analysis of 1 H NMR self-diffusion of deuterium solutions of CDs shows that, for all three natural CDs, diffusion coefficients depend linearly on the CD volume fraction, suggesting that these molecules are behaving as nonaggregate hard spheres. A similar conclusion was reached from the analysis of the dependence of mutual diffusion coefficients on CDs concentration [58][59][60].…”

Diffusion coefficients of the ternary system (2-hydroxypropyl-β-cyclodextrin+caffeine+water) at T=298.15K

“…In fact, in our case, diffusion coefficients for some aqueous CD solutions [12][13][14][15] and caffeine solutions at T = 298.15 K [16] have been reported, but as far as the authors know, after careful literature search, no data are available in literature for ternary systems involving 2-hydroxypropyl-b-cyclodextrin (HP-b-CD) and caffeine molecules for the same concentrations at 298.15 K. Thus, the purpose of this work has been to measure ternary mutual diffusion coefficients (D 11 , D 22 , D 12 , and D 21 ) for T = 298.15 K at carrier concentrations from (0.000 to 0.010) mol Á dm À3 , for each solute, respectively, by using a Taylor dispersion equipment, helping us to better understand the structure of these systems. The description of this technique is well done in the literature [17][18][19][20][21][22][23], and consequently we only report a summary concerning the experimental procedure.…”