are reported for aqueous solutions of lactose, sucrose, glucose, and fructose at various concentrations (0.001 to 0.1) mol‚dm-3 and temperatures (298.15 to 328.15) K. The hydrodynamic radius and activation energy for the diffusion of aqueous sugars are calculated from those results. In addition, the measured diffusion coefficients are used with the Hartley equation to estimate activity coefficients for aqueous lactose, sucrose, glucose, and fructose.

Binary mutual diffusion coefficients (interdiffusion coeffcients) have been measured for aqueous solutions of -cyclodextrin ( -CD) at concentrations from (0.002 to 0.008) mol‚dm -3 . The effect of temperature, from (298.15 to 312.15) K, was also analyzed. The concentration dependence of D is discussed on the basis of Hartley's equation. The activation energy for the diffusion process, 18719 J‚mol -1 , was calculated from data of D at different temperatures. This activation energy is in good agreement with that estimated using Stokes-Einstein equation (18644 J‚mol -1 ). Activity coefficients for aqueous -CD solutions were also estimated from Hartley equation and experimental D.

Binary mutual diffusion coefficients measured by the Taylor dispersion method are reported for aqueous solutions of α-cyclodextrin (α-CD), 2-hydroxypropyl-α-cyclodextrin (HP-α-CD), and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) at concentrations from (0.002 to 0.010) mol·dm-3 at temperatures from (298.15 to 312.15) K. The hydrodynamic radius and activation energy for the diffusion of aqueous α-CD, HP-α-CD, and HP-β-CD are calculated from the experimental results. In addition, the Hartley equation and the measured diffusion coefficients are used to estimate activity coefficients for aqueous α-CD, HP-α-CD, and HP-β-CD.

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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.

A Taylor dispersion method is used to measure ternary multicomponent diffusion coefficients of three-component liquid systems. Ternary mutual diffusion coefficients measured by this method (D 11, D 22, D 12, and D 21) are reported for aqueous solutions of β-cyclodextrin (β-CD) + caffeine at 298.15 K at carrier concentrations from (0.000 to 0.010) mol·dm−3, for each solute, respectively. These diffusion coefficients have been measured having in mind a better understanding of the structure of these systems and the thermodynamic behavior of caffeine and cyclodextrin in solution.

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