Contributions of diffuse layer sorption and

Dzombak, D. and R. J. Hudson (1995) Ion Exchange The Contribution of Diffuse Layer Sorption and Surface Complexation, in Aquatic Chemistry, C. P. Huang et al., Eds. ACS Washington D.C. 

The Contributions of Diffuse Layer Sorption and Surface Complexation... 

Dzombak, D.A., and Hudson, R.J.M. 1995. The contributions of diffuse layer sorption and surface complexation, in C.P.H. Huang, C.R. O Melia, and J.J. Morgan, eds., Aquatic Chemistry. Interfacial and Interspecies Processes, Advances in Chemistry Ser., vol. 244, Washington D.C., American Chemical Society, Chap. 3, pp. 59-93. 

A set of limiting cases of transport is developed, comprising of situations where diffusion through the void space, fiber space and external boundary layers, each contribute significantly to transport. By means of a scaling analysis, the conditions under which each limiting case is valid are identified. Finally, a comparison of the model predictions with experimental data indicates that the model is capable of describing transient sorption dynamics quite well. 

Calculate the plate height contributed by sorption-desorption mass transfer (nonequilibrium) through a uniform liquid layer (configuration factor q = 2/3) of thickness 1.0 x 10 3 cm coated on the inside of an open tubular (capillary) column. The gas velocity v is 10 cm/s. The solute retention ratio is 0.10 and its diffusion coefficient Ds through the stationary liquid is 1.0 x 10 5 cm2/s. 

Thus, any approach has to consider in principle both contributions the chemical, nonelectrostatic, or intrinsic contribution, and the electrostatic one. Now, to model ion sorption to soil colloidal particles, two main approaches exist chemical modeling (should not be confused with the chemical contribution mentioned in the preceding discussion) and adsorption modeling in the first case, the sorption is treated as a chemical reaction, with the free surface sites considered as a reactant, and a chemical equilibrium expression in terms of the bulk activities is written. In adsorption modeling, an appropriate adsorption isotherm is employed however, it is not written in terms of the bulk activity a, of the adsorbate, but instead it should be related to the activity at the outer Helmholtz plane a, 2> is, at the limit of the diffuse double layer, X2 in Figure 11.1 (see also Section 3.3.3). Both are related, due to the condition of constancy of the electrochemical potential (Section 3.1.1), by... 

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