Debye-Hiickel parameter local

The expression for the excess Gibbs energy is built up from the usual NRTL equation normalized by infinite dilution activity coefficients, the Pitzer-Debye-Hiickel expression and the Born equation. The first expression is used to represent the local interactions, whereas the second describes the contribution of the long-range ion-ion interactions. The Bom equation accounts for the Gibbs energy of the transfer of ionic species from the infinite dilution state in a mixed-solvent to a similar state in the aqueous phase [38, 39], In order to become applicable to reactive absorption, the Electrolyte NRTL model must be extended to multicomponent systems. The model parameters include pure component dielectric constants of non-aqueous solvents, Born radii of ionic species and NRTL interaction parameters (molecule-molecule, molecule-electrolyte and electrolyte-electrolyte pairs). 

Here and t] are, respectively, the relative permittivity and the viscosity of the electrolyte solution. This formula, however, is the correct limiting mobility equation for very large particles and is valid irrespective of the shape of the particle provided that the dimension of the particle is much larger than the Debye length 1/k (where k is the Debye-Htickel parameter, defined by Eq. (1.8)) and thus the particle surface can be considered to be locally planar. For a sphere with radius a, this condition is expressed by Ka l. In the opposite limiting case of very small spheres (Ka 3> 1), the mobility-zeta potential relationship is given by Hiickel s equation [2],... 

Ramshaw has pointed out that in the y- 0 limit, one can regard the core parameter 0 as a geometric parameter describing the degree of ellipticity of a spheroidal cavity used in defining a local field in a phenomenological mean field treatment. Such a treatment, described by Ramshaw, is the analog of the Debye-Hiickel treatment of a simple ionic fluid. 

It is at this point that a problem appears in Cherfs method as outlined in his thesis. In order to duplicate his results, the Imig range contribution was calculated on a molality basis, and the local composition model was calculated on a mole fraction basis. This discrepancy was corrected in the paper published in the AIChE Journal (C4) for single electrolyte sdutions. As can be seen in Chapter IV, the Pitzer-Debye-Hiickel expression used for the long range contribution was normalized to the mole fraction basis. Due to these differences, the interaction parameters presented in the paper for use with the Pitzer Debye-Huckel version differ from those presented in the thesis. The AIChE Journal paper notes that a paper on multicomponent solutions was being prepared so this section will be updated later. The Chen method cannot be used in the multicomponent test systems until then. 

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