Analysis and Parametric Sensitivity of the Behavior of Overshoots in the Concentration of a Charged Adsorbate in the Adsorbed Phase of Charged Adsorbent Particles: Practical Implications for Separations of Charged Solutes

Abstract

In this work, an analysis of the parametric sensitivity of the overshoot in the concentration of the adsorbate in the adsorbed phase, which occurs under certain conditions during an ion-exchange adsorption process, is presented and used to suggest practical implications of the concentration overshoot phenomenon on operational policies and configurations of chromatographic columns and finite bath adsorption systems. The results presented in this work demonstrate and explain how the development of an overshoot in the concentration of the adsorbate in the adsorbed phase could be enhanced or suppressed by (i) varying the diffusion coefficient, D3, of the adsorbate relative to the diffusion coefficients, D1 and D2, of the cations and anions, respectively, of the background/buffer electrolyte, (ii) altering the initial surface charge density, δ0, of the charged adsorbent particles, (iii) varying the Debye length, λ, and (iv) changing the initial concentration, Cd30, of the adsorbate in the bulk liquid of the finite bath. The influence of the pH and ionic strength, I∞, of the liquid solution on the development of an overshoot in the concentration of the adsorbate in the adsorbed phase is also presented and discussed through the relationships of these parameters to δ0 and λ, respectively. Furthermore, a detailed explanation of the effects of each parameter on the interplay between the diffusive and electrophoretic molar fluxes, as well as on the structure and functioning of the electrical double layer, which are responsible for the concentration overshoot phenomenon, is presented.

Department(s)

Chemical and Biochemical Engineering

Sponsor(s)

University of Missouri--Rolla. Biochemical Processing Institute

Keywords and Phrases

Charged Adsorbate; Charged Adsorbent Particles; Adsorption; Diffusion; Electrophoretic Migration; Electrical Double Layer; Surface Charge Density; Debye Length; PH; Ionic Strength; Hydrogen-ion concentration

International Standard Serial Number (ISSN)

0021-9797

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2004 Elsevier, All rights reserved.

Publication Date

01 May 2004

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