close

Вход

Забыли?

вход по аккаунту

?

Bilirubin removal from albumin-containing solutions dynamic adsorption on anionic resin.

код для вставкиСкачать
ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING
Asia-Pac. J. Chem. Eng. 2010; 5: 708–713
Published online 18 September 2009 in Wiley Online Library
(wileyonlinelibrary.com) DOI:10.1002/apj.395
Research Article
Bilirubin removal from albumin-containing solutions:
dynamic adsorption on anionic resin
V. Piemonte* , L. Turchetti and M. C. Annesini
Department of Chemical Engineering Materials & Environment University of Rome, La Sapienza via Eudossiana 18, 00184 Roma, Italy
Received 28 January 2009; Revised 21 July 2009; Accepted 22 July 2009
ABSTRACT: In this paper, kinetics of unconjugated bilirubin adsorption in fixed-bed anionic resin columns was
investigated. Experimental breakthrough curves were determined at different feed flow rates and using inlet solutions
with different bilirubin and albumin concentrations. A mathematical model is provided to describe the effect of albumin
on bilirubin adsorption equilibrium and kinetics in a fixed-bed column.
Breakthrough curves show that a significant bilirubin concentration is present in the column outlet stream even in
the early operating time. This result shows that, with the flowrates used in this work, adsorption is slow with respect to
the axial convection in the column and, as a consequence, bilirubin is never completely removed from the liquid phase.
The results obtained in this paper may be useful for the design of liver support devices such as Molecular Adsorbent
Recirculating System (MARS), which implement anion-exchange columns to remove albumin-bound toxins from
concentrated albumin solutions.  2009 Curtin University of Technology and John Wiley & Sons, Ltd.
KEYWORDS: fixed-bed adsorption; bilirubin; albumin; liver support LDF
INTRODUCTION
The liver can be considered a complex large-scale biochemical reactor that displays a unique biologic complexity. In case of liver failure, functional replacement
presents one of the most difficult challenges in substitutive medicine. In recent years, liver transplantation
was shown to be the only clinically effective method
of treating acute and acute-on-chronic hepatic failure.
However, this ultimate therapeutic approach is limited
by the growing disparity between organ donations and
the number of patients on the waiting list. For these reasons, many efforts have been carried out in the research
on liver support systems for use as a temporary measure,
either bridging patients to transplantation or helping
to keep them alive until the recovery of native liver
function.[1 – 3]
As acute and acute-on-chronic liver failure are clinical conditions associated with high plasmatic levels of
various types of toxins, therapy of severe liver failure
is essentially based on blood detoxification.
Small, hydrophilic toxins, such as urea, can be
removed by a conventional dialysis process over rather
selective membranes, which avoid the depletion of
*Correspondence to: V. Piemonte, Department of Chemical Engineering Materials & Environment University of Rome La Sapienza
via Eudossiana 18, 00184 Roma, Italy.
E-mail: piemonte@ingchim.ing.uniroma1.it
 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
biologically valuable macromolecules like blood proteins and hormones. Different detoxifying processes are
required for toxins that are tightly bound to plasma proteins such as albumin because a simple dialysis process
cannot remove them selectively and effectively at the
same time. Among these toxins, an important role is
played by bilirubin, which is a standard marker of the
clinical state of liver-failure patients and exhibits an
extremely high affinity for albumin.
At present, the two most popular artificial liver
devices are Molecular Adsorbents Recirculating System (MARS) (Teraklin AG, Rostok, Germany now
Gambro AB, Lund, Sweden) and Prometheus (Fresenius Medical Care AG, Bad Homburg, Germany).
MARS implements the albumin dialysis process,[4,5]
including on-line regeneration and recirculation of
the dialysate solution. The regeneration process consists of conventional low-flow dialysis followed by
adsorption in two different columns loaded with activated carbon and cholestyramine anion-exchange resin,
respectively. Prometheus[6] implements the Fractionated
Plasma Separation and Adsorption (FPSA) process[7] ;
in this device, plasma is filtered from blood along
with albumin and smaller molecules, circulated in
closed loop through one anionic resin and one nonionic resin column in series, and then sent back
into the patient’s blood circuit. In both cases, bilirubin removal is mainly carried out by anionic resin
columns.
Asia-Pacific Journal of Chemical Engineering
Another interesting liver support device that implements an adsorption process is the Biologic-DTPF
system.[8] This device combines the Biologic-DT
hemodiabsorption system, capable of removing low
molecular weight compounds, in series with the Biologic PF push and push–pull pheresis system, capable
of removing large molecules by means of membranes
that separate the patient’s plasma to allow direct contact
between plasma and sorbents. In the case of Biologic
DTPF, adsorption is not carried out in a fixed-bed column, but the sorbent is suspended in the solution that
must be purified.
Adsorption processes could limit duration and efficacy of clinical sessions with the aforementioned liver
support devices because, for instance, when saturation
of adsorptive media occurs, the treatment is ineffective
for the removal of albumin-bound toxins[9] ; therefore, a
deeper knowledge of adsorption equilibrium and kinetics of albumin-bound toxins may give important information for the optimisation of existing clinical devices
and for the design of new ones. Unfortunately, while
several papers[8 – 10] are aimed at assessing the clinical
performance of liver support systems, there is a lack
of literature that is devoted to the investigation of the
fundamental unit operations implemented in the detoxification processes.
In this paper, fixed-bed adsorption kinetics of unconjugated bilirubin on anionic resin was investigated. In
order to obtain experimental data at constant inlet concentration, experimental tests were performed in oncethrough flow and bilirubin breakthrough curves were
obtained. Different feed flow rates and different inlet
bilirubin and albumin concentrations were used in order
to investigate the effect of liquid phase velocity and
albumin over bilirubin adsorption. Finally, the collected
data were analysed by means of a modified linear
driving force (MLDF) model, which accounts for the
albumin effect on bilirubin adsorption equilibrium and
kinetics.
EXPERIMENTAL
Materials
Bovine serum albumin (Cohn fraction V, MW =
66 000, isoelectric pH = 5) and bilirubin (unconjugated
mixed isomers, MW = 584.7) were purchased from
Sigma-Aldrich and used as received.
Amberlite anionic resin IRA 400 (chloride form) was
purchased from Sigma-Aldrich and used as adsorbent.
The properties of this strongly basic, gel-type resin are
as follows: quaternary ammonium functional groups,
1.4 meq/ml wetted bed volume, 8% cross-linkage, particle size 0.3–0.8 mm. Before adsorption experiments,
the resin was equilibrated with a buffer solution at pH
7.4 and then partially dehydrated by vacuum filtration.
 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
BILIRUBIN FIXED-BED ADSORPTION ON ANIONIC RESIN
In these conditions, a residual moisture content of 55%
was evaluated.
All the chemicals used were of reagent grade.
All the solutions were prepared in a phosphate buffer
0.15 M at pH 7.4
Methods
The analysis of albumin–bilirubin solutions was carried out spectrophotometricallly by a Perkin-Elmer
LAMBDA 25 UV–Vis spectrophotometer. As the
bilirubin absorption spectrum depends on the albumin
concentration in the solution, the total bilirubin concentration was evaluated by calibration line at the isosbestic
point (λ = 416 nm), where the bilirubin extinction coefficient does not depend on the albumin/bilirubin molar
ratio.[11,12] Albumin concentration was evaluated by a
calibration line at the wavelength of 279 nm by taking
into account bilirubin absorption at the same wavelength.
Fixed-bed column experiments
Fixed-bed adsorption tests were carried out in a glass
column (10 mm internal diameter, 60 mm length),
loaded with a fixed amount of anionic resin (M = 2.8 g)
and supported by a porous Teflon septum. Before each
experiment, the column was rinsed with a phosphate
buffer (pH = 7.4 and ionic strength 0.15 M).
The column was equipped with a thermostat jacket in
order to keep the temperature at 25 ± 0.5 ◦ C. Preliminary control experiments carried out at this temperature
showed that the albumin–bilirubin solution degradation
did not occur within a period of 16 h.
The inlet solution was fed to the top of the column
by means of a variable speed peristaltic pump.
Owing to the very low bilirubin solubility in water at
a neutral pH, albumin-free solutions were not used in
the experimental runs.
Albumin–bilirubin solutions with different bilirubin
concentrations (from 40 to 100 µM) were fed to the column at different flow rates in order to have a column
residence time in the range 0.7–2 min. It is worth noting that the residence time in the experiments is of the
same order of magnitude as that of MARS adsorption
columns: MARS data sheets report an albumin flow-rate
range of 50–200 ml/min and a column bed volume of
250 ml; assuming a void fraction of 0.4, a residence
time of about 0.8 min can be estimated.
The column outlet stream was sent to a UV–Vis spectrophotometer (Lambda 25, Perkin Elmer, Waltham,
MA, USA) equipped with a quartz flow cell and the
bilirubin concentration was continuously measured by
the absorbance reading at a wavelength of 416 nm.[12]
In order to assess the effect of albumin on bilirubin
adsorption, solutions at different albumin concentration
were fed to the column at a constant flow rate of
Asia-Pac. J. Chem. Eng. 2010; 5: 708–713
DOI: 10.1002/apj
709
V. PIEMONTE, L. TURCHETTI AND M. C. ANNESINI
Asia-Pacific Journal of Chemical Engineering
Table 1. Experimental conditions of kinetic runs
(T = 25 ± 0.1 ◦ C, pH 7.4, M=2.8 g).
0
Cbil
, µM
0
CAlb
, µM
1.08
1.08
1.08
0.7
1.96
1.08
1.08
99.0
99.0
99.0
102.0
104.0
73.2
39.3
89.6
140.0
178.8
134.0
129.0
139.0
134.0
1
0.8
cbil/cinbil
B1
B2
B3
B4
B5
B6
B7
Q, ml/min
(a)
0.6
0.4
0.2
0
B1
B2
B3
0
50
100 150 200 250 300 350 400 450
t (min)
(b)
1.08 ml/min. The albumin concentration spans from 90
to 180 µM in order to have a bilirubin/albumin molar
ratio between 0.2 and 1.0 that also covers the real case
of the MARS treatment.
In all the experiments, the outlet bilirubin concentration was determined at regular time intervals.
A summary of the operating conditions used in the
experimental runs is presented in Table 1.
1
cbil/cinbil
0.8
0.6
0.4
0.2
B2
B6
B7
0
0
RESULTS
In all the experiments, albumin concentrations were
not found to vary significantly after contact with the
anionic resin. This finding is consistent with the result
of Annesini et al .,[13] , who, for the same resin used in
this paper, report a negligible adsorption capacity for
albumin.
Figure 1(a) and (b) reports bilirubin breakthrough
curves obtained by varying inlet albumin and bilirubin
concentrations, while Fig. 1(c) reports the results of
experimental runs performed at different flow rates;
in each case, the outlet-to-inlet concentration ratio is
plotted versus time.
It is worth noting that, even in the early operating
time when the column is far from saturation, bilirubin
is never completely removed from the liquid phase. This
finding, also confirmed by some clinical data obtained
during a MARS treatment,[14] , has a fundamental relevance in the design of an albumin regeneration system
because it suggests that, in the present configurations of
devices such as MARS, bilirubin is never completely
cleared from the albumin dialysate.
Furthermore, the data reported in Fig. 1(a) confirm
the negative effect of albumin on bilirubin adsorption
as already reported in previous works.[12,15,16] .
Bilirubin adsorption in the fixed-bed column can
be described by means of an unsteady state, onedimensional model that couples the differential bilirubin
 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
100 150 200 250 300 350 400 450
1
0.8
0.6
0.4
0.2
0
B2
B4
B5
0
50
100 150 200 250 300 350 400 450
t (min)
Figure 1. Breakthrough curves of albumin–
bilirubin solutions: (a) different albumin concentrations (B1, B2, B3); (b) different bilirubin concentrations (B2, B6, B7); (c) different flow rates
(B2, B4, B5).
mass balance in the column with mass transfer kinetics
from the liquid to the adsorbed phase.
Considering both solute convection and axial dispersion in the liquid phase, bilirubin mass balance in the
column can be written as follows:
ε
DISCUSSION
50
t (min)
(c)
cbil/c0bil
710
∂cbil
∂nbil
∂ 2 cbil
∂cbil
+ (1 − ε)ρr
= Dz
−v
2
∂t
∂t
∂z
∂z
(1)
where cbil is the total (free and albumin-bound) bilirubin
concentration in the liquid phase, nbil is the bilirubin
adsorbed amount per unit sorbent mass, is the
bed porosity, ρr is the intrinsic density of the solid
adsorbent, v is the liquid superficial velocity and Dz
Asia-Pac. J. Chem. Eng. 2010; 5: 708–713
DOI: 10.1002/apj
Asia-Pacific Journal of Chemical Engineering
BILIRUBIN FIXED-BED ADSORPTION ON ANIONIC RESIN
is the bilirubin axial dispersion coefficient. Assuming
linear driving force (LDF) mass transfer kinetics,[17] the
bilirubin mass balance in the adsorbed phase may be
written as
3
∂nbil
∗
= kc (nbil
− nbil )
(2)
∂t
R
∗
is the solute adsorbed amount per unit sorbent
where nbil
mass at equilibrium with the liquid phase, nbil is the
actual solute adsorbed amount per unit sorbent mass, kc
is the LDF mass transfer coefficient and R is the radius
of adsorbent particles.
Equations (1) and (2) were integrated with the initial
and boundary conditions:
nbil = 0
∂cbil
in
+ vcbil (3)
= −Dz
t > 0, z = 0, vcbil
∂z
∂cbil
t >0 z =H
=0
∂z
t =0 0≤z ≤H
cbil = 0;
in
where cbil
is the bilirubin concentration in the inlet
solution.
From a general point of view, in order to predict
the breakthrough curves, the longitudinal dispersion
coefficient, the equilibrium conditions and the LDF
mass transfer coefficient are required.
As for the dispersion coefficient Dz , the correlation proposed by Chung and Wen[18] was used. This
correlation accounts only for hydrodynamic dispersion, neglecting the contribution of molecular diffusion.
Therefore, Dz is a function of the liquid flow rate and
bed geometry and is independent of the chemical nature
and molecular size of the solute.
The equilibrium conditions for albumin–bilirubin
adsorption are largely detailed in previous
works[12,13,15,16] . Here, only the main results are briefly
summarised.
Considering strongly albumin-bound toxins, such as
bilirubin[19] and high albumin-to-bilirubin molar ratios
in solution, the adsorption isotherm can be simply
written in terms of the total bilirubin concentration
cbil
(4)
nbil = n bil
k + cbil
with the following apparent constants that are functions
of the total albumin concentration calb
c alb
n bil = A exp − ∗
(5)
c
k = mbil calb
(6)
Values of parameters A, c ∗ and mbil are reported in
Table 2. The thermodynamic model used accounts for
the reduction in bilirubin adsorption due to bilirubin
competitive binding between albumin and sorbent. This
aspect was also accounted for in the model proposed by
Patzer et al .[20] Furthermore, with respect to the work
of Patzer, the model used here accounts for a reduction
in the bilirubin adsorption capacity as experimentally
observed.[13,15,16]
Because no significant change was observed in the
albumin concentration in the experimental tests, the
total albumin concentration calb can be considered as
being constant.
Finally, the LDF mass transfer coefficient, kc , is
a lumped parameter that, in general, depends on the
diffusion resistance in the solid phase and on the
Table 2. Parameters used in the theoretical model.
Parameter
ε
mbil
A
c∗
Q
Vc
M
τ
µ
λ
Pe
St0
a
b
(a)
(b)
Definition
Description
Value
Units
0.4
0.24
48.9
1245
0.7 ÷ 2
1.4
2.8
0.7 ÷ 2
–
–
µmol/g
µM
ml/min
ml
g
min
Solute phase capacity ratio
9·10−4 ÷ 2.2·10−3
–
Isotherm linearity parameter
0.19 ÷ 0.47
–
(b)
–
1.6·10−3 ÷ 3.7·10−3
0.043
0.54
–
min−0.54
–
Bed void fraction
Eqn (6)
Eqn (5)
Eqn (5)
Vc /Q
in
Vc cbil
∗
in
M nbil (cbil
)
1
in
1 + cbil
/k
Hv
Dz
3 k 0τ
R c
Eqn (7)
Eqn (7)
Liquid flow rate
Column liquid holdup
Adsorbent mass
Column residence time
Axial Peclet number
Stanton number
Annesini et al .[13]
Correlation from Chung and When[18] (Pe = 0.01/ + (0.02/)Re 0.48 )
 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Asia-Pac. J. Chem. Eng. 2010; 5: 708–713
DOI: 10.1002/apj
711
V. PIEMONTE, L. TURCHETTI AND M. C. ANNESINI
Asia-Pacific Journal of Chemical Engineering
fluidodynamics of the liquid phase. Owing to the semiempirical nature of the LDF model, kc was considered
as a fitting parameter, determined by matching the
theoretical model with the experimental breakthrough
curves. In this case, in order to improve the model
adaptability to the experimental data, a MLDF was
considered, assuming kc to be a decreasing function of
time
kc0
(7)
kc (t) =
1 + at b
This time dependence of kc can be related to the formation of a further, time-increasing, diffusional barrier
to bilirubin transfer to the solid phase.
Equations from (1) to (3) and (7) can be rewritten in
the following dimensionless form:
1 ∂
nbil
1 ∂ 2
cbil
cbil ∂
∂
cbil
+
=
−
2
∂
t
µ ∂
t
Pe ∂
∂
z
z
∂
nbil
cbil
= St
−
nbil
∂
t
λ + (1 − λ)
cbil
St0
St =
1 + aτ b t̃ b
t = 0 0 ≤
z ≤1 cbil = 0 nbil = 0
1 ∂
cbil
t > 0, z = 0, −
+
cbil = 1
Pe ∂
z
∂
cbil
t >0 z =1
=0
∂
z
0.005
0.004
0.003
St0
712
0.002
0.001
0
0
0.5
1
1.5
2
2.5
τ [min]
Figure 2. LDF Stanton number St0 Vs. column residence
time τ .
(8)
(9)
(10)
(11)
in
∗
in
where cbil = cbil /cbil
,
nbil = nbil /nbil
(cbil
), z = z /H , t=
t/τ and τ is the column residence time.
Definitions of dimensionless parameters St, Pe, λ and
µ are reported in Table 2 along with their values.
The set of differential equations was solved by using
gPROMS (Process System Enterprise, London, UK) by
using a backward finite difference method.
The model was fitted to experimental data using a, b
and St0 as adjustable parameters. While a and b were
assumed to have a fixed value for all the experiments,
St0 was assumed to vary with flow rate.
Fitting of the experimental data with the least squares
method gives a = 0.043 min−0.54 and b = 0.54, while
St0 values span in the range 1.6·10−3 –3.7·10−3 . Fitted breakthrough curves are superimposed to the corresponding data-set points in Fig. 1 (for the sake of
clarity, dimensional time is used in the plot), showing that the model used is consistent with experimental
measurements.
The optimal St0 values obtained for each data set are
plotted as a function of column residence time τ in
Fig. 2. Linear regression of these data gives a value of
St0 /τ = 3kc0 /R = 1.86·10−3 ± 4.86·10−5 min−1 . The
linear trend observed for St0 vs τ suggests that the LDF
mass transfer coefficient is rather independent of the liquid phase velocity (with the operating conditions used
 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
in the experimental tests, St0 appears to be controlled by
diffusion inside adsorbent particles). Furthermore, St0 is
not affected by the albumin concentration in the liquid
phase.
The results obtained with the model presented in this
paper suggest that bilirubin fixed-bed adsorption kinetics cannot be satisfyingly described by a classical LDF
model. A better description is obtained by considering a
time-increasing diffusional barrier to bilirubin transfer
to the solid phase, leading to a MLDF model with a
mass transfer coefficient depending on the time.
CONCLUSION
Fixed-bed adsorption kinetics of bilirubin on anionic
resin was studied in albumin-containing solutions.
Breakthrough curves show that a significant bilirubin
concentration is present in the column outlet stream
even in the early operating time. This result shows that,
with the flow rates used in this work, adsorption is slow
with respect to axial convection in the column and, as
a consequence, bilirubin is never completely removed
from the liquid phase. As the experimental column
residence times used in this paper are comparable to
those of actual MARS adsorption columns, it may
by concluded that a similar limitation affects MARS’
albumin regeneration circuit. Indeed, this hypothesis is
also supported by some data acquired during a clinical
MARS treatment.
Breakthrough curves were analysed by means of a
mathematical model based on MLDF mass transfer
kinetics that accounts for a time-increasing bilirubin
transfer resistance. This further resistance could be due
to the formation of an albumin skin layer on the resin
surface.
The information presented in this paper can be
helpful for the optimisation of existing liver support
Asia-Pac. J. Chem. Eng. 2010; 5: 708–713
DOI: 10.1002/apj
Asia-Pacific Journal of Chemical Engineering
devices and for the design of new ones; nevertheless,
for a complete assessment of the performance of the
adsorption columns used in artificial liver devices, a
similar analysis should be extended to the adsorption
of other albumin-bound toxins involved in liver failure,
like biliar acids and mercaptanes.
SYMBOLS USED
Dz
DEA
FPSA
H
LDF
MARS
MLDF
Pe
R
St0
St
calb
cbil
in
cbil
kc
k
nbil
∗
ntry
n bil
v
M
Bilirubin axial dispersion coefficient
Differential and algebraic equations
Fractionated plasma separation and adsorption
Column bed height
Linear driving force
Molecular adsorption recirculating system
Modified linear driving force
Axial Peclet number
Radius of sorbent particles
LDF Stanton number
MLDF Stanton number
Total albumin concentration
Bilirubin concentration in the liquid phase
Bilirubin concentration in the inlet solution
Mass transfer coefficient
Apparent Langmuir parameter
Solute sorbent amount per unit sorbent mass
Solute sorbent amount per unit sorbent mass at
equilibrium with the liquid phase
Apparent Langmuir parameter
Liquid superficial velocity
Sorbent mass
BILIRUBIN FIXED-BED ADSORPTION ON ANIONIC RESIN
µ
ρr
τ
Solute phase capacity ratio
Intrinsic density of anionic resin
Column residence time
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
R. Jalan, S. Sen, R. Williams. Gut, 2004; 53, 890–898.
B.G. Stegmayr. Transfus. Apher. Sci., 2005; 32, 209–220.
J. Rozga. Xenotransplantation, 2006; 13, 380–389.
J. Stange, S. Mitzner, W. Ramlow, T. Gliesche, H. Hickstein,
R. Schmidt. ASAIO J., 1993; 39, M621–M625.
J. Stange, W. Ramlow, S. Mitzner, R. Schmidt. Artif. Organs,
1993; 17, 809–813.
K. Rifai, T. Ernst, U. Kretschmer. J. Hepatol., 2003; 39,
984–990.
D. Falkenhagen, W. Strobl, G. Vogt. Artif. Organs, 1999; 23,
816.
J. Steczko, S.R. Ash, D.E. Blake, D.J. Carr, R.H. Bosley.
Artif. Organs, 1999; 23, 310–318.
P. Evenepoel, B. Maes, A. Wilmer, F. Nevens, J. Fevery,
D. Kuypers, B. Bammens, Y. Vanrenterghem. Blood Purif.,
2003; 21, 244–252.
D. Falkenhagen, M. Brandl, J. Hartmenn, R.-H. Kellenr,
T. Posnicek, V. Weber. Ther. Apher. Dial., 2006; 10,
154–159.
R.G. Reed. J. Biol. Chem., 1977; 252, 7483–7487.
M.C. Annesini, L. Di Paola, L. Marrelli, V. Piemonte,
L. Turchetti. Int. J. Artif. Organs, 2005; 28(7), 686–693.
M.C. Annesini, V. Piemonte, L. Turchetti. In Biochemical
Engineering (Ed.: F.E. Dumont), Nova Science Publisher Inc.,
New York, 2009.
M.C. Annesini, V. Piemonte, L. Turchetti, V. Morabito,
G. Novelli. Chem. Eng. Trans., 2009; 17, 1095–1100.
M.C. Annesini, V. Piemonte, L. Turchetti. Chem. Eng. Trans.,
2007; 11, 551–556.
M.C. Annesini, C. di Carlo, V. Piemonte, L. Turchetti.
Biochem. Eng. J., 2008; 40, 205–210.
E. Glueckauf, J. Coates. J. Chem. Soc., 1947; 1315–1321.
S.F. Chung, C.Y. Wen. AIChE J., 1968; 14, 857–866.
G. Blauer, E. Lavie, J. Silfen. Biochem. Biophys. Acta, 1977;
492, 64–69.
J.F. Patzer. Artif. Organs, 2008; 32, 499–508.
Greek Symbols
λ
Bed void fraction
Isotherm linearity parameter
 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Asia-Pac. J. Chem. Eng. 2010; 5: 708–713
DOI: 10.1002/apj
713
Документ
Категория
Без категории
Просмотров
3
Размер файла
167 Кб
Теги
albumin, bilirubin, solutions, removal, containing, adsorption, anionic, resins, dynamics
1/--страниц
Пожаловаться на содержимое документа