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The Use of Ion‐Selective Electrodes for Evaluating Residence Time Distributions in Expanded Bed Adsorption Systems
Author(s) -
FernándezLahore Héctor M.,
Lin DongQiang,
Hubbuch Jürgen J.,
Kula MariaRegina,
Thömmes Jörg
Publication year - 2001
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp010118z
Subject(s) - residence time distribution , tracer , expanded bed adsorption , raw material , adsorption , chemistry , fluidized bed , volumetric flow rate , analytical chemistry (journal) , chromatography , process engineering , elution , mineralogy , mechanics , inclusion (mineral) , physics , organic chemistry , nuclear physics , engineering
Abstract The suitability of ion‐selective electrodes (ISE) for the determination of residence time distribution (RTD) in turbid, cell‐containing fluids was examined. The electrodes were found to give reproducible signals in biomass‐containing feedstock with up to 20% wet weight of solids. The enhanced feedstock compatibility of IES, when compared to other tracer sensing devices, allows the study of expanded bed system hydrodynamics under relevant operating conditions. Within the linear range of the corresponding ISE‐tracer pair, both examined ISE (Li + ‐ or Br − ‐selective) showed to be insensitive against the range of flow rate and pH normally employed during expanded bed adsorption (EBA) of proteins. Analyzing the RTD obtained after a perfect ion tracer pulse in terms of the PDE model (PDE, axially dispersed plug‐flow exchanging mass with stagnant zones) gave a quantitative description of the underlying hydrodynamic situation during EBA processing. These data provided a powerful tool to make predictions on the adsorptive global process performance with a defined feedstock type and composition. The link between the hydrodynamic events during feedstock application and the actual process performance was shown when applying intact yeast cell suspensions at different biomass content (up to 7.5% wet weight) and buffer conductivity (5−12 mS) onto an EBA column filled with the adsorbent Streamline Q XL as fluidized phase. On the basis of our experimental results, a guideline for the successful application of the ISE/RTD method to EBA process design is presented.