Model-based analysis and quantitative prediction of membrane chromatography: extreme scale-up from 0.08 ml to 1200 ml.

A model-based approach is presented for quantitatively decoupling the impacts of non-ideal flow and non-ideal binding in membrane chromatography (MC) capsules at different scales. The internal geometry of Sartobind capsules with 0.08 ml and 1200 ml membrane volume is reconstructed from MRI measurements and manufacturer data. Based on this information, computational fluid dynamics (CFD) simulations are used for computing internal flow patterns of both capsules. Measured breakthrough curves (BTC) under non-binding conditions are used for calibrating PFR and CSTR models of the holdup volumes in the Äkta systems. A suitable binding model is determined and the binding parameters are estimated from binding BTC data of the 0.08 ml capsule. Due to the decoupling of non-idealities, the binding parameters can be directly transferred between the CFD models of both capsules. This advantage is used for quantitatively predicting BTC data of the 1200 ml capsule under binding conditions. The model-based prediction excellently matches with independently measured BTC data, facilitating an extreme scale-up factor of 15,000. The presented approach has previously been shown to be universally applicable to capsules from other vendors with different flow configurations and membrane types.

Membrane Based Measurement Technology for in situ Monitoring of Gases in Soil.

The representative measurement of gas concentration and fluxes in heterogeneous soils is one of the current challenges when analyzing the interactions of biogeochemical processes in soils and global change. Furthermore, recent research projects on CO(2)-sequestration have an urgent need of CO(2)-monitoring networks. Therefore, a measurement method based on selective permeation of gases through tubular membranes has been developed. Combining the specific permeation rates of gas components for a membrane and Dalton's principle, the gas concentration (or partial pressure) can be determined by the measurement of physical quantities (pressure or volume) only. Due to the comparatively small permeation constants of membranes, the influence of the sensor on its surrounding area can be neglected. The design of the sensor membranes can be adapted to the spatial scale from the bench scale to the field scale. The sensitive area for the measurement can be optimized to obtain representative results. Furthermore, a continuous time-averaged measurement is possible where the time for averaging is simply controlled by the wall-thickness of the membrane used. The measuring method is demonstrated for continuous monitoring of O(2) and CO(2) inside of a sand filled Lysimeter. Using three sensor planes inside the sand pack, which were installed normal to the gas flow direction and a reference measurement system, we demonstrate the accuracy of the gas-detection for different flux-based boundary conditions.