ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 1, pp. 58! 61. + Pleiades Publishing, Ltd., 2006.
Original Russian Text + V.M. Sedelkin, T.O. Ryabukhova, N.A. Okisheva, M.G. Pozdeeva, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80,
No. 1, pp. 59! 62.
OF SYSTEMS AND PROCESSES
Adsorption of Albumin on Charcoal-Filled Cellulose
V. M. Sedelkin, T. O. Ryabukhova, N. A. Okisheva, and M. G. Pozdeeva
Engels Technological Institute, Branch of Saratov State Technical University, Engels, Saratov oblast, Russia
Received February 14, 2004
Abstract-Cellulose diacetate ultrafiltration membranes for separation of protein!carbohydrate raw materials
are fabricated, and their performance characteristics (porosity, permeability, and selectivity) are examined.
Among the common methods for increasing the
food and biological values of dairy products is intro-
duction of additional amounts of protein and deficient
amino acids, e.g., lysine and threonine. For this pur-
pose, components derived from the secondary dairy
material, whey, are widely used.
Whey is a natural by-product from manufacture of
cheese, cottage cheese, and dairy-proteinic concen-
trates; it is classed with secondary dairy products.
Data on the composition of whey are given in the
Whey contains fat and protein particles (sus-
pended), and also lactose and minerals.
Ultrafiltration is widely used in processing dairy
products . In ultrafiltration, retention is caused
primarily by the screening effect. However, adsorption
of particles on the membrane surface also contributes
significantly. Commercial membranes UAM-500 used
for ultrafiltration of whey are not mechanically strong
and exhibit practically no adsorption properties. Fur-
thermore, their formulation includes such plasticizers
and additives as formamide and magnesium perchlo-
rate, whose contact with foodstuffs is undesirable.
In this study we examined the adsorption of pro-
teins on ultrafiltration membranes based on cellulose
diacetate (CDA) or, in any case, on cellulose acetate
with the degree of substitution g<240, modified with
charcoal (it was introduced to increase the adsorption
capacity and improve the mechanical characteristics
of the membranes).
In fabricating CDA ultrafiltration membranes by
the dry-wet formation procedure, we used two frac-
tions of charcoal: fine (85 mm) and coarse (160 mm),
which were obtained by screening through Capron
sieves. The mean degree of polymerization of CDA
Polymer macromolecules used for fabricating
membranes should be sufficiently rigid or be capable
of forming supramolecular structures. This is neces-
sary, first, to obtain a loose matrix in formation of
asymmetric membranes, and, second, to eliminate
glass transition in the polymer during exploitation of
the membranes, thus preventing their deformation
under pressure. Cellulose esters meet these require-
ments in full measure. Furthermore, an important
criterion is the inertness of a polymer against the
components to be separated.
Thus, it appears quite reasonable to use cellulose
acetate as a material for ultrafiltration membranes.
The membranes were produced from 5, 7, and 10%
CDA solutions in acetone. A fixed amount of charcoal
was added to the acetone solution, and the mixture
was thoroughly stirred. To study the protein adsorp-
tion on the membranes, we used a blood substitute
(10% albumin stabilized with NaCl). The adsorption
was studied interferometrically . The experimental
isotherm of the excess adsorption of albumin on the
charcoal-filled membranes is shown in Fig. 1.
Composition of whey
³ Content, %
³ ash ³ fat ³ protein ³ lactose ³minerals
Sweet ³ 6.5 ³ 0.20 ³ 0.70 ³ 4.50 ³ 0.50
Acid ³ 6.0 ³ 0.20 ³ 0.80 ³ 4.20 ³ 0.60