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A Mathematical Model for Kinetic Study of Analyte Permeation from Both Liquid and Gas Phases through Hollow Fiber Membranes into Vacuum
journal contribution
posted on 2000-08-03, 00:00 authored by Alexey A. SysoevA mathematical model and a Matlab-5 computer code
have been developed to study the dynamic response of
the hollow fiber membrane probe. The depletion layer
formation at the sample/membrane interface is taken into
consideration by the mathematical model for the liquid
mobile phase. The code produces concentration profiles
within a sample feed stream and in the membrane. Flux
values at the vacuum side of the membrane can also be
calculated as a function of time. The method can be
applied both for gas and liquid feed streams. Concentration profiles in a mobile phase and the flux of analytes
through the hollow fiber membrane inlet have been
studied with this simulation technique as a function of
the liquid-phase flow rate. The influence of the formation
of a layer of the analyte depletion during the dynamic
response has been considered. The shape of the depleted
layer and selectivity of permeation from a liquid mobile
phase through the membrane into the vacuum are shown
to be dependent on the mobile-phase flow rate. In addition, for studied conditions, formation of a depletion layer
is demonstrated to be fast compared with membrane
diffusion. Thus, if a homogeneous aqueous sample is
coming through the inlet cross-section of a hollow fiber
membrane containing pure water, the response time
mostly depends on analyte diffusivity in the membrane.
However, if the aqueous sample is coming through the
inlet cross-section of a hollow fiber membrane containing
clean air, response time also depends on equilibrium
analyte concentration in the depletion layer.