Tracer diffusion in aqueous sucrose and urea solutions

1990 ◽  
Vol 68 (9) ◽  
pp. 1611-1615 ◽  
Author(s):  
Allan J. Easteal
Keyword(s):  
Diffusion Coefficients ◽  
Relative Viscosity ◽  
Tracer Diffusion ◽  
Proton Exchange ◽  
Specific Viscosity ◽  
Sucrose Solutions ◽  
Diaphragm Cell ◽  
Tracer Diffusion Coefficients ◽  
Viscosity Dependence

Tracer diffusion coefficients for water (as HTO), methanol (14CH3OH), and acetonitrile (CT3CN) in aqueous sucrose (10–25% w/w) and urea (0.25–4 mol L−1) solutions at 298 K have been determined using the diaphragm cell technique. For sucrose solutions tracer diffusion coefficients vary with the 2/3 power of the relative viscosity and the viscosity dependence is the same for the above tracers as for sucrose and oxygen. In urea solutions tracer diffusion coefficients appear to have a solute-specific viscosity dependence, but the solute specificity is largely removed when the effects of proton exchange and urea dimerisation are considered. Keywords: diffusion, water, methanol, acetonitrile, sucrose, urea.

Tracer diffusion coefficients of tritiated water and acetonitrile in water + acetonitrile mixtures

1980 ◽  
Vol 33 (8) ◽  
pp. 1667 ◽  
Author(s):  
AJ Easteal
Keyword(s):  
Diffusion Coefficients ◽  
Structural Model ◽  
Tritiated Water ◽  
Tracer Diffusion ◽  
Solution Viscosity ◽  
Composition Region ◽  
Self Diffusion ◽  
Composition Variation ◽  
Diaphragm Cell ◽  
Tracer Diffusion Coefficients

Tracer diffusion coefficients of tritiated water (HTO) and 14C-labelled acetonitrile have been measured at 298.15 K by the diaphragm cell method, for the whole range of compositions of water+ acetonitrile binary mixtures. The composition variation of (a) the deviation of D from additivity and (b) the product Dη, for each component, has been evaluated. The variation of Dη is discussed in terms of the Naberukhin- Rogov structural model for solutions of non-electrolytes in water. ��� The diffusion data have been used to test a semiempirical relationship, between solution viscosity and self-diffusion coefficients, due to Albright. For the composition region of 5-55 mole % acetonitrile Albright's equation gives calculated viscosities which agree well with observed values. The calculation fails to reproduce the observed variation of viscosity for the composition region of 60-95 mole % acetonitrile.

Non-Stoichiometry and Cation Tracer Diffusion Studies in the Magnetite-UlvÖSpinel Solution, (Fe,Ti)3-δO4

1994 ◽  
Vol 369 ◽  
Author(s):  
Sanjeev Aggarwal ◽  
Rudiger Dieckmann
Keyword(s):  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
Oxygen Activity ◽  
Spinel Solid Solution ◽  
Low Oxygen ◽  
Cation Diffusion ◽  
Deviation From Stoichiometry ◽  
Diffusion Studies ◽  
Tracer Diffusion Coefficients ◽  
Point Defect Structure

AbstractCation diffusion in the spinel solid solution (Fe1-xTix)3-δO4 (0≤ x ≤ 0.3) was investigated at 1200 ºC as a function of oxygen activity, aO2 and cationic composition, x. At different cationic compositions, cation tracer diffusion coefficients, D*Me of Me = Fe and Ti were measured as a function of oxygen activity. Plots of log DMe vs. loga0 show V-shaped curves, indicating that different types of point defects prevail at high anc low oxygen activities. Thermogravimetric experiments were conducted, using a high resolution microbalance, to determine the deviation from stoichiometry in (Fe1-xTix)3-δO4 at 1200 °C. δversus log aO2 curves are S-shaped. An analysis of the oxygen activity dependences of thecation diffusion coefficients and the deviation from stoichiometry with regardto the point defect structure suggests that at high oxygen activities cation vacancies are the predominant defects governing the deviation from stoichiometry and the diffusion ofcations. At low oxygen activities, and at small values of x, cation interstitials determine the deviation from stoichiometry, while they dominate for 0 ≤ x ≤ 0.3 inthe cation diffusion.

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