Donnan equilibrium. Hypernetted-chain study of one-component and multicomponent models for aqueous polyelectrolyte solutions
- Univ. of California, Berkeley, CA (United States)
The hypernetted-chain integral equation has been applied to two polyelectrolyte models to study the Donnan equilibrium for an aqueous mixture containing large polyions and ordinary ionized salts. The first is a traditional one-component model with the polyions interacting via a screened Coulomb potential. The second is a multicomponent model, which describes the solution as an aqueous mixture of a highly asymmetric electrolyte where polyions, counterions, and co-ions are represented by charged hard spheres. The polyion-polyion distribution functions and the Donnan pressure are evaluated for a range of typical experimental conditions for aqueous solutions of globular proteins. The results show that a screened Coulomb potential model provides a good approximation if the charge on the polyions is not too high. However, there are some important differences between the results of one-component and multicomponent models for the polyion-polyion distribution function. At concentrations above 1 M of simple electrolyte, there is a region of interparticle distances for which the potential of mean force is attractive according to the multicomponent model; while this effect is not reproduced by the one-component model based on the screened Coulomb potential alone, it is shown correctly when the authors include an {open_quotes}osmotic{close_quotes} potential due to the presence of the small ions. Using the hypernetted-chain theory, a one-component model provides a successful analysis of experimental osmotic-pressure data of aqueous solutions of bovine serum albumin in 0.15 M sodium chloride for albumin concentrations up to 450 g/L. 33 refs., 6 figs., 1 tab.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 554930
- Journal Information:
- Journal of Physical Chemistry, Vol. 96, Issue 15; Other Information: PBD: 23 Jul 1992
- Country of Publication:
- United States
- Language:
- English
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