The cross-flow chromatographic separation of carbohydrate mixtures

Abstract

Reviews are given of the theoretical aspects of chromatography
and of continuous chromatographic techniques.

A pilot-scale rotating annular chromatograph has been
constructed consisting of two concentric cylinders which form an annulus
1.4m in length and 12mm wide. The annular space is filled with
ion-exchange resin. The upper and lower surfaces of the annulus are
enclosed by stainless steel flanges. The entire bed is rotated slowly at
speeds of up to four revolutions per hour. Feed solutions are introduced via
a Stationary inlet distributor into a layer of glass beads at the upper surface
of the column packing. Deionised water as eluent is also introduced to the
upper surface of the packing. Each component in the feed mixture has a
different retention time within the resin. The rate of travel of each solute
combined with the rotation of the annulus causes each component to exit
the annulus at a different position. Products pass through the lower
stainless steel flange and into a stationary collector beneath the annulus.

Several carbohydrate mixtures have been separated with varying
degrees of success. Glucose has been separated from its isomer fructose
in synthetic solutions and in inverted beet molasses. Mixtures of glucose,
fructose and sucrose have also been resolved quite successfully. These
separations were carried out on Purolite PCR 833 ion exchange resins in
the Ca2+ form. Sucrose has been separated from betaine and other
non-sugars in ordinary beet molasses using Duolite C211/2558 ion
exchange resin in the Na+ form.

A total throughput of 309 hl sugar solids has been shown to be
readily achievable to give 300g h™' glucose (4.8% w/v concentration, 90%
purity) and 240g h"! fructose (2.6% w/v concentration, 90% purity). This
corresponds to a specific throughput of 56.8 Kg sugar solids m3 resin h-1.

A computer simulation program has been developed which can be
used to predict quite accurately the peak positions and peak bandwidths of
solutes leaving the annulus, product purities, yields and throughputs.

Date of Award	1987
Original language	English