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Sp ISSN 0081-3397
•art I I - KINETICS AND APPLICATION
By
S. A L L A M(Atomic Energy Establishment, Cairo, Egypt)
M. BARRACHINA(Junta de Energía Nuclear, Madrid, Spain)
Toda correspondencia en relación con este traba-jo debe dirigirse al Servicio de Documentación Bibliotecay Publicaciones, Junta de Energía Nuclear, Ciudad Uni-versitaria, Madrid-3, ESPAÑA.
Las solicitudes de ejemplares deben dirigirse aeste mismo Servicio.
Los descriptores se han seleccionado del Thesaurodel INIS para describir las materias que contiene este informe con vistas a su recuperación. Para más detalles cónsultese el informe IAEA-INIS-12 (INIS: Manual de Indizacion) yIAEA-INIS-13 (INIS: Tesauro) publicado por el OrganismoInternacional de Energía Atómica.
Se autoriza la reproducción de los resúmenes ana-líticos que aparecen en esta publicación.
Este trabajo se ha recibido para su impresión enJulio de 1. 974
Depósito legal n° M-24295-1974
CONTENTS
I9 INTRODÜCTION „ 1
II. EXPERIMENTAL .. 5
II.1» Preparation of barium sulfate.....•••.•••.. 5
II.2. Preparation of granular barium sulfate. <,. e 9 5
II.3» Radionuclides...» „ 6
11 = 4» Apparatuso „. o o«o. „ * 6
II.5» Heterogeneous ion-exchange reactions**..».e 7
IIo6« Ion-exchange studies on packed beds of
sint er ed BaSO, Bsoa08,8aeao .<». 7
III. RESÜLTS AND DISCUSSION* 9
IIIo1« Isotopic ion exchange reaction in thesystem BaS04(s)/*Ba^+(aq) «> 9
I I I .1 .1 . Influence of temperature «o.. . . 10III e 1.2, Influence of acidity.». 15
III»2. Heterogeneous non-isotopic ion exchangereactions. 19
III.2.1. The system BaSO4(s)/*Sr2+(aq) 19
111.2.2. The system BaSO. (s)/^Y3+(aq) 21
111.2.3. The System BaS04(s)/*Ce3+(aq)o., 25
III.2.4» The system BaSO4(s)/*Os+(aq) 28
III.2«5e General discussion of results ...o» 31
Page
IV. APPLICATION. 35
IV. 1. Adsorption of individual fission productstracers on columns of BaSO, 35
IV. 1.1 o Cesium-137..... 35
IV, 1.2. Strontium-85 35
IV. 1.3. Yttrium-88 36
IV. 1.4. Cerium-144 36
IV. 1.5. Barium-133 39
IV.2. Adsorption of a mixture of fission productson BaSO^. 39
IV»3e Pission products group separation on BaSO,coluinn o 7 40
V. APPENDIX I 47
GOMPUTER ANALYSIS OF EXPERIMENTAL DATA BASED
ON A THREE EXPONENCIAL SYSTEM
VI. AOKNOWLEDGEMENT 53
VII. REFERENCES. 55
HETEROGENEOUS ISOTOPIC AND NON-ISOTOPIC ION EXCHANGE
ON THE SURFACE OF BARIUM SULFATE
Part II — Kinetics and Application
By
S9 ALLAM* and Ma BARRACHINA*^
I. INTRODUCCIÓN
The isotopic and non-isotopic ion exchange behav-
iour of the different cations on the surface of solid
BaSO, have long been exploited in the separation of the
fission products into a number of groups on columns of
BaS0.9 Barrachina and Sauvagnac (1) have used small col-
umns of the finely devided solid to determine the radio-
chemical composition of the raw solutions used in the
industrial recuperation of the long lived fission prod-
ucts. Under these oonditions pressure was applied to the
* Nuclear Chemistry Department, Atomic Energy Establish-ment, Cairo, Egypt.
** Nuclear Chemistry División, JEN, Madrid, Spain.
columna in order to percolate the solution through the
solid phase.
Kraus et al (2) have reportad that packed beds of
BaSO. incorporated into tantalum oxides were very effec-
1 "V7 1Y7tive in the separation of Ba and J Cs radioactive
isotopes from acid solutions. Por practica! purposes,
Lieser and Hild (3) have suggested the use of ion ex-
changs columna filled with BaSO. precipitated on silica
2+ 2-5-gel for the quantitative separation of Ba , Sr and
2+Oa radioactive ions from aqueous solution. Kar et al
(4) have presented a procedure for the chemical and
2+ ^+radiochemical separation of Sr and Y ions in mix-
2+ture, which was based on the selective carrying cf Sr
ions by ignited BaSO,.
It has been shown earlier (5) that the fine mesh
crystals of BaSO. can be converted to a larger mesh
size by the sinterization of the solid at 800 G. The
agglomeration of the powdered solid by thermal treat-
ment proved to be very effective in providing solid
BaSO. with suitable performance as a column material.
The present work reporta more detailed studies
on the heterogeneous isotopic and non-isotopic ion
exchange between sintered and unprocessed BaSO. and
the Gs+, Ba2+, Sr2+, Y3+, 0e3+ and Ge4+ ions, in order
to calrify some aspects of the complex nature of their
exchange mechanism. The optimum conditions for the pre-
liminary separation of the forthmentioned cations from
fission products are also discussed»
lio EXPEHIMENTAL
II.1. Preparation of barium sulfate
Dissolve 25 g BaOlg^HgO in a total volume of 2,5 1
water and add 420 mi of freshly prepared 0.5 M ammonium
(ethylenedinitrilo) tetra-acetate solution. Dilute the
mixture to 4 1 and adjust the pH to 10 witii concentrated
ammonium hydroxide solutionB Add 250 g ammonium persulfate,
JgSgOgj and stir to dissolve? then place on a hot
píate and digest for 8 h at 70 C8 Decant the precipítate
and digest in 4 1 of water for another 20 h at 70 C.
Leave to age for 24 h at room temperature, then filter
in a crucible of médium porositye Wash throughly with
hot water? a small volume of acetone and oven dry at
110°Ga
11,2» Preparation of granular "barium sulfate
The solid preparsd by the previously mentioned
method was converted to a granular form as follows.
The BaSO. was mixed vyith 10 i» its weight water and
the mixture was pressad in molds of hard steel into tab-
leta of approximately one inch diameter under a pressur©
of 1 ton/cm e The tableta wer® dried at 11O°C and di-
rectly transfered to the calcination oven and sintered
for 1 h at 800°C. The sintered discs ware grinded in
agate mortars to avoid any surface contamination and the
samples were then clasified to the desired grain size by
utilizing manual sieves*
II.3» Badionuclides
The following radioaetive isotopes were obtained
from Amersham (England)» The "^Ba was obtained in the
form of chloride in 111 HC1 solution with aetivity of
1 mCi/ml. and barium content of 117 ug/ml» Carrier-free
Sr, Y, ^Ge and ->'Gs radioaetive tracers were
obtained in the form of chlorides in 1M HC1 solution.
Ho4« Apparatus
The heterogeneous exchange reactions were carried
in batch experiment using 100 mi scratch-free flaaks
which were fitted in a thermostated electric shaker
Model "HeronM. The liquid samples were filtered with a
Milipore device.
The specific surface área of the solid samples was
measured by the BET method (5) using a Perkin-Elmer-Shell
spectrometer, Model 212-13.
A 2 x 2 inch Nal(TI) scintillation crystal coupled
to a fully automatic multitube Philips counter was used
for the activity measurments.
A 4000 Hewlett-Packard multichanel analyzer Model
5401A coupled to a G-e-Li detector was used for all the
gamma spectrometric analysis.
Glass columns of 10 mm x 15 cm were used for the
preparation of the sintered BaSO. bed.
II«5o Heterogeneous ion-exchange reactions
The isotopie and non-isotopic ion exchange reactions
were carried in the system BaSO, (s]/%(aq), where M was
Cs+? Ba
2+S Sr
2+? Y
3+, Ce3* and Ge4+ ions.
A known weight of BaSO. was stirred in a certain vol-
ume of water for 24 h prior to the exchange experiment, to
obtain a constant concentration of Ba ions in the aqueous
phaseo In this manner? a constant surface área of the solid
was also maintained throughout the exchange reaction. One mi
of the diluted radioactive solution was then added and the
starting time of the reaction was fixed for each flask
separately. The liquid samples were withdrawn from the dif-
ferent flasks at a certain time and rapidly filtered, then
gamma countede
Carrier free radioactive isotopes were used in these
experiments to avoid any precipitation reaction.
II.6 Ion-exchange studies on packed beds of sintered BaSO,
The ion-exchange columns were prepared by previously
soaking the solid (grain size 200 to 500 micron) in a 50 mi
8
water for 24 h. The mixture was poured into the column
and washed with several column volumes of water. The
hight of the BaSO. bed was 4.7+0.1 cm and the average
weight of th.e used solid was 7»8 g. The elution curves
were obtained by collecting fractions of the effluent
and measuring their activity.
III. RESULTS AND DISCüSSION
III.1, Isotopic ion exchange reaction in the system
BaSO4(s)/*Ba2*(aq)
2 +The isotopic ion exchange reaction between Ba
ions in the aqueous phase and those on the surface of
BaSO. have been carried with solid dried at 110°C and
solid sintered at 800°0o As was shown earlier (5)? the2 +number of exchangeable Ba ions on the surface of
BaSO, can be calculated from the isotopic ion exchange
measurments by using the following equation;
= ( 1) — (D
where:
nn i W1 co
2 +n_ = number of exchangeable Ba /g BaSOA.
2 +n-, = number of Ba /mi in the aqueous phase.
i = count rate in the solution at the be-gining of the reaction.
i = count rate at equilibrium.
? = volume of solution (mi).
W = weight of BaSO. (g).
The number of exchangeable Ba /mi in the aqueoua
10
phase was calculated by applying the following formula:
nx = - ^ 1 . A (2)103
where:
K = solubility product of BaSO..
A = Avogadro's number.
The count rate at equilibrium i was determined by
graphical extrapolation of the plot of i/iQ versus ex-
change time on a semi-logarithmic scale? as shown by
Fig. 1.
A Fortran Y programme for the Univac-1106 has been
applied for the analysis of the two-component exponential
curves (5). By computing the experimental data obtained
from the ion exchange reactions in the various systems,
the half-time valúes for the short and long term reaotions
have been determined with greater accuracy» Furthermore,
this programme determines the i /i for the final resulta
of ti and Ti valúes and, accordingly, the number of es-s s
2+
changeable Ba ions on the surface of BaSO. can be cal-
culated.III.1.1. Influence of temperature
The isotopic ion exchange reaction was carried at
different temperatures up to 70°C. The results of these
experiments are summerized in Table I. It was noticed that
11
1.0-Q
0.5-
0.2
0.1-
0.05
[a] The ratio i/ i
90 120Time (min.)
Hetsrogeneous isotopie ion-sschange reaction in
the system BaS04(s)/^Ba2+(aq)
Oounting rata in the solution plotted as afunction of tim©
TABLE I
Effect of temperature on the isotopic ion exchange reaction in
the system BaSO,(s)/*Ba +(aq)
BaSO,
Temp.
(°c)
30
50
70
n l
6,26.10 1 5
8,47.1O15
9,17.1O15
Solid dried at 110°0
**(min)
2.1
1.4
0.93
(min)
640
127
60
i /iCO 0
0.19
0,14
0.18
n s
2,58e1O19
4.16.1019
3,34o1019
Solid sintered at 800°C
**(min)
11
7
7
(min)
360
150
95
0.35
0.07
0.07
n s
1,13«1O19
9,O.1O 2 0
9,7.1020
Through.out this report the ncontinental" method of numbering is used, e.g. 6.26 x 10
15is printed as 6,26.10 .
15
13
TABLE II
Effect of acidity on the isotopio ion exchange reaction
in the system BaSO-(s)/*Ba (aq)
Médium
HgO
NaN03
(0.1M)
HNO3
(0.01M)
HC1
(0.01M)
HCIO^
(0.01 M)
BaSO, dried a t 110°G
(min)
2.1
2.1
2 a 7
2 o 0
2 .7
(min)
640
887
143
286
1436
3,4Oe1O3
O,8O.1O3
O?7O.1O3
0,98.103
1,60.103
BaSO. s in te red at 800°0
**(min)11
32
2 . 5 .
25
12
(min)
360
555
77
212
138
1,5O.1O3
0,80.103
O?63»1O3
0,67.103
1,10.103
14
O30 40 50 60 70
Temperature (°C)
Plge 22+
Number of exchangeable Ba ' ions on thesurface of one gram BaSO. plotted as afunction of reaction temperatxire.
• solid dried at 110uC.o solid sintered at 800°0.
15
the half-time (ti) for the fast surface exchange reac-
tion and the half-time (Ti) for the slow diffusión or"5
recrystallization processes, decreased with temperatura.
It can be seen from Figo 2, that the number of ex-
changeable Ba ions on the surface of sintered BaSO¿
increased very sharply with temperatures up to 50 C. On
the other hand, the reaction temperature had no effect
2-fon the number of exchangeable Ba ions on the surface
of the unsintered solida
III.1.2. Influence of acidity
Por these experiments, BaSO. sintered at 800 C
(grain size 200 to 500 microns) and the oven dried solid
were used. The resulta of the isotopic ion exchange re-
actions in the different acid media at pH 2 are sum-
merized in Table lio The exchange reaction in 0,01M
HNO- solution showed a fair similarity in the exchange
behaviour of the sintered and the unprocessed BaSO^o
However, this was not the case for the reactions carried
in the presence of hydrochloric or perchloric acid solu—
tions, Pigo 3 and 4»
As a general trend9 the ratio of the number of
2+
exchangeable Ba ions on the surface of the solid to
those in solution other than the aqueous médium was found
to decrease to a certain extent? in the presence of the
16
0.5-
0.2-
0.1-
0.06-
K c , t1/2= 25 min.
^ . J V """"** ^ ~*——»—
i i
T1 /2 = 212 min.
i i0 30 60 90
Time (min)
. 3
Heterogeneous ion exciaaage reaction in the system
BaS04(s)/*3a2+ (0.0111 HC1)
© solid dried at 110°C
o solid sintered at 800°C
17
1.0-í
0.5-
rnin.
i/i.
0.2-
0.1-
T1/2=1436min
T1/2=138 mm.
0.06-0 60 120 180 240 300
Time (min)360
Fifí. 4
Heterogeneous exchange reaction in the system
BaS0.(s)/*Ba2+ (0.01 M
© solid dried at 110°0
o solid sintered at 800°C
18
acid and sodium nitrate media* A likely explanation for
the observed decrease in the ng/n-, would be due to an
increase in the n-, valué, caused by the saline effect.
2+
In electrolyte solutions, the number of Ba ions in
the liquid phase cannot be calculated by directly ap=
plying equation 2, used for reactions in aqueous solu-
tion8o In this case, the activity of the ions present
in acid solutions have to be taken into consideration.
19
«2. Heterogeneous non-isotopio ion exchange reaotions
III.2.1, The system BaS0¿(s)/*Sr2+(aq)
The heterogeneous non-isotopic ion exchange be—
2+ 2+tween Sr ions in the aqueous phase and Ba ions onthe surface of BaSO, was carried by using the carrier-
Qr
free Sr isotope. In this manner? the precipitation of
SrSO, on the surface of BaSO. was avoided,
The results of the reactions carried with the oven
dried BaSO, and the sintered solid are presented by
Figo 5» It was observed that in the presence of sintered
solid, the activity of the Sr ions in the solution re-
mained constant for a long period of time after the ini-
tial fall off at the begining of the reaction. The half-
time (Ti) of the slow reaction was found to be very large,
2+which proved that the Sr ions did not participate in
the recrystallization of BaSO,.
On the other hand, no decrease in the activity of
2+Sr ions in acid solutions was observed in the presence
of both types of solidse The same reaction was carried
in 0.1M sodium nitrate solution and, as in acid solution,
no decrease in the activity was measurable. These observa-
tions are very useful for later on applications in the
separation of Sr + ions on packed beds of sintered
20
1.0-9» t1/2= 3.7 min
iOon o,
t,,o=1.9 min
0.5-
¡/¡c
0.2
0 . 1 -
0.05-
T1/2> 10 min.—o-
T1/2=2734 min.
T270 480 14400 90 180Time (min)
Fig* 5
Heterogeneous non-isotopic exohange reaction
in the systein BaSO4(s)/*Sr2+(aq)
• solid dried at 110°C
o solid sintered at 800 C
21
III.2.2. The system BaSO,(s)/*Y3+(aq)
In the reaction between Y ions in the aqueous
phase and Ba + ions on the surface of BaSO. dried at 11O°C,
no decrease in the activity of the carrier free Y iso-
tope was observed over a period of 48 h,
On the contrary, a very rapid fall off in the activity
of Y ions in the solution was obtained in the presence
of the sintered solida The results of this experiment are
given by Fige 60 It was also noticed that the counting
rate in the solution remained constant after the sharp
decrease at the begining of the reaction.
The high affinity of the sintered BaSO, for Y 3 + ions
can not be entirely due to a surface exchange reaction,
otherro.se a slight exchange could have been noticeá with the
unprocessed solids A very likely explanation would be that
the sinterization of BaSO. has caused the formation of
stable and meta-stable polycrystalline solidso During the
recrystallization of the deformend BaSO.s the active
sorption cites trapped the comparatively smaller Y ions,
forming solid solutions0 Purthermore, no measurable de-
crease in the activity of the Y ions was observed in the
presence of nitriCj hydrochloric and perchloric acid solu-
tions for both types of solids.
The exchange reaction was also carried between Y
ions in 0.1M sodium nitrate solution and the sintered
22
1.0-
0.5-t1 /2 = 4min.
i/i.
0.2-
0.1-
0.05-
0.03-0 90
T1/2>
180
min.
i i
1 i |270 360 1440
Time (min)Pig. 6
Exclianae reaction in the system Ba50A(s)/ Y (aq.)
solid barium sulfate sintered at 800 0
T,,o= 1730 min
120 180 240 3000.1
0 60
Time (min)
Fig . 7
Heaction in the system BaSO. (s)/*?f3+ (0.1M NaNO,)
í1/2 = 0.7 min
0.2
0.1
0.05-0 60 120 180 240
Time (min)
Pig. 8
Reaction in the system BaSO.(s)/*Ce^+(aq), solid
dried at 110°G
25
BaSO.» The results are presented in Fige 7» In spite of
the marked decrease in the solid uptake of the Y^+ ions
in the sodium nitrate solution, the half-time of the
fast reaction remained the same as in the aqueous médium*
III«2.3. The System BaSO,(s)/*Ce3+(aq)
Por these experimenta? the solid dried at 110 C
and the sintered BaSO. were usedo The decrease in the
activity of the carrier-free ^Oe in the aqueous phase
was measured as a function of time o The results are given
by Figo 8 for the reaction carried with the unprocessed
solid and by Figo 9 for the reaction with sintered BaSO.»
In both casesf it was thought that two reactions
have taken placev a fast surfac© eschange reaction and a
slower diffusión reaction0 Howevers a computer analysis
of the experimental data to a two component exponential
curve provided very erroneous results. On manipulating
the experimental results for successive entrances, the
programme provided data for a three component exponential
system (see Appendis I) 9
Therefor©9 thre© possibilities in this case can be
proposedo A fast surface adsorption reaction between the
Ge ions in the solution and the SO- ions on the sur-
face of the solido An intermediary ion exchange reaction
26
0.00460 120 180 240
Time (min)
Fig. 9
Reaction ±n the system 3aS0A(s)/ Ge (aq), solid
sintered at 800
2?
0.9060 120 180 240
Time (min)Fig. 10
Heterogeneous non-isotopic ion-exchange in
the system 3aS04(s)/*Ce3+ (0.01M HNO3)
@ solid dried at 110°C
o solid sintered at 800°G
28
between the CeJ ions in solution and the Ba ions on
the solid surfacee Finally a slower adsorption or diffu-
sión reaction into the crystal lattices whieh. aooount for
the longterm decrease of activity in the solution.
For reactions oarried in acid solutionss a very
small decrease in the activity of Ce" ions in the solu-
tions was equally observed in the presence of 0.01M solu-
tions of nitrie? hydrochloric and perchloric acids. As can
be seen from Figa 10 and 11, it seemed that an ion exchange
reaction has taken place at the begining of the experiment,
but no further decrease in the activity was observed after
a long period of time» In other words9 the Ge ions were
not enriched on the surface of BaSO- in acid mediumo
The non-isotopic exchange reaction was also carried+2
in a similar study between cerio ions in solution and Ba
ions on the surface of the unprocessed and sintered BaSO ,»
A comparitively lower enrichment of th© Ce ions in aque-
ous and acidic media waa observed in the presence of both
types of solids.
III«2.4. The system BaS04(s)/*Gs+(aq)
Por the reaction between Gs ions in the solution
2+and Ba ions on the surfac© of unsintered BaSO. a very
small but measurable decrease in the activity of the car-
rier-free J Gs tracer was obtained. On the other hand, a
29
t1/2=22 min.
o 0.94H
0.92-
0.90-
T | /2> 104min.
T1/2>104 min.
0 60 120 180 240Time (min)
Pie. 11
Heterogeneous non-isotopic ion exchange in
the system BaSO.(s)/ Ge^+ *
9 solid dried at 110°C
o solid sintered at 800°C
30
1.0-f
T1/2= 2948 min.
60 120 180 240Time (min)
Reaction in the system BaSO.(s)/*Cs (aq),
solid barium sulfate sintered at 800 G
31
more pronounced fall off in the activity of the Gs+ ions
was observed in the presence of the sintered BaSO,,
Fig. 12. At the begining of the experiment, it seemed
that a surface exchange reaction took place but the ac-
tivity remained constant over a long period of timea This
implied that the Os ions were neither enriched on the
surface of BaSO. ñor participated in the recrystalliza-
tion of the solida The high sorption capacity of the sin-
tered solid for the Cs+ ions was probably due the deforma-
tion of the BaSO, crystals during the sinterization proc=
ess? as previously explainedo
IIIo2e5« Señera! discussion of resulta
The resulta of the isotopic and non-isotopie
ion exchange reactions in the previously discussed sys-
tems are gusmerized in Table III» The pereent exchange
valúes were calculated from the experimental resulta
over an exchange period of 24 iu
It was interesting to notice that the trivalent
cerium and yttriun ions behaved similarly in the pres-
ence of the sintered BaSO.» Purhtermores the Ge^+ ions
were highly enriched on th© surfsce of the unsintered
solid while the Y^ ions ahowed no signe of exchange
in aqueous or acidic media. On the other hand, the sol-
+ 2 +id uptake of Gs and Sr ions was much lower than its
affinity for the trivalent cations, However, no conclu-
sion can be drawn for the relation between the cationie
charge and the amount of exchange on the BaSO¿ surfaoeo
In the non-isotopic ion exchange reactions with
both types of solids9 the presence of H or Na ions in
the liquid phase inhibited the solid affinity for the
different cationsQ On compairing the ionio radii mth
2+
respect to that of the Ba ionf it can be seen that ions
with smaller radii and higher mobility were preferably
captured by the solid in acid or sodium nitrate solutionse
In aqueous médium^ cations mth smaller radii such as
Ge- and Y were rapidly captured by the actif e sorp=»
tion cites of the sintered solida for it would be easier
for such ions to enter the crystal lattioes of the de=
formed solid during the recrystallization process.
TABLE III
Ion Exchange Behaviour of the Various Cations in Aqueoua and Acid Solutions
The preaented percent uptake was caloulated from the experimental resulta
based on a 24 hours reaotion time
Ba2 +
Sr'2 +
3+
Aq.
91.1
55
90
75.4
BaSO. dried at 110 C
HNO.
79
HC1*
73
H0104*
83
NaNO**1
82
No decrease in activity
16 16 24 25
No decrease in activity
No decrease in activity
18 No decrease in activity
BaSO. sintered at 800 0
Aq«
83*5
26
99*5
52.4
94
60.5
HNO.
88
HC1
74
* HG10 *
98
NaNO.
89
No decrease in activity
8 14 14.5 24
No decrease in act iv i ty
No decrease in activity 60.7
No decrease in ac t iv i ty
* 0.01M * * 0.1M
34
x£c£\
cOü
16 24 32 40Effiuent Volume (mi)
Pig» 13
ELution of cazrier-free ^'Cs ana Srtracer activity froa sintered BaSOcolusin with water at a flow rate of0.1
35
IV, APPLICATION
The difference in the exchang© behaviour of the pre-'
viously discussed cations in aqueous and acidic media
offers a good possibility for their separation in groups
by utilizing ion exchange columna of sintered BaS0,o
IVa1o Adsorption of individual fission products tracers
on oolumns of BaSC>4
IVo1.1. Gesium-137
It has been found that on eluting the earrier-
free J'Cs from the coluian with water, the actiTity in
the effluent rose sharply within the first 3 nil volume
forming a well-defined peak0 It can be seen from Fig« 13
that the fall~off in the activity was rather rapid whioh
means that the Cs ions were not retained by the BaSO-s
IV.1a28 Strontium°°85
Q[-
In this experimenta the carrier-free Sr activ-
ity was passed through the column at a flow rate of
0.1 ml/min, The elution curve is illustrated in Fig9 13^85
It can be seen that the rapid elution of the Sr activ-
ity with water at the begining is very similar to that
36
1 7
of the JICs activity, However, the decrease in the ac-
tivity of the effluent. was rather gradual, resulting. in a
tailing front boundary of the elution curve, This is main-2+
ly due to the partial fixation of the Sr ions on thesurface of BaSO,.
o183« Yttrium-88
88One mi of the diluted carrier-free Y tracer solu-
tion was added to a column of sintered BaSO., previously con-
ditioned with watere The activity of the effluent rose very
slowly after the first 8 mi of HgOj then the counting rateoo
was constant for the next 200 mi, which implied that the Y
activity was no longer eluted with water9 Elution with 0«1M
NaNO- solution resulted in a peak with an mnusal tailing,
as can be seen from Pig8 14» A more well-defined peak was
obtained upon eluting with 1M NaNO^ solution, A rapid elu-88
tion of the Y activity was achieved with 0.1M HNO, re-
sulting in a sharp peak, Pigo 15»
IV.1.4. Gerium-144
Elution of the carrier-free Ce activity with
0.1M NaNO^ solution resulted in a fíat peak, Pig, 16, M.th
further elution runs with the same eluant the peak became
flatter still, showing that the activity was now less read-
144ily eluted from the column, In a sepárate run, the Ge
37
i
Ox
Ec'E
OO
12-
10-
8 -
6 -
4 -
2 -
0 -
I M Na NO,
1 / ° \ / ° " 1 M NaN03
\ \\ \
/ V V _/ ^^_~ T ~ I I I !
O 4 8 12 16 20 24
Effluení Volume (mi)
Pig. 14
Elution of esarLer-^ree ^ Y from sintered BaSO^column with sodium n i t r a t e solution at a flowrate of 0,1 ml/miru
IOX
1
enc3Oü
4 -
04 8 12 16 20
Effiuent Volumeíml)
Fig* 15
ELution of carrier-free Y with C1Msolution at a flow rate of 0,1 ml/min.
was eluted with 0.1M HNO^ solution at a flow rate of
0.1 ml/min. It was noticed that the breakthrough of the
cerium activity was very sharp and occured earlier, The
shape of the elution curve in Fig8 16 indicated that the
Ce^ ions were not retained by the BaS0¿.
IV.1.5. Barium-133
2 +It has been found that the Ba ions were stron-
gly retained by the solid BaSO.. No traces of activity
was detected in the effluent after eluting with severa!
column volumes of 091M HNO, solution,, Furthermores avery
slow rise in ths aotivity of the effluent was measured
on using 1M HNO^ as an eluant* However? the activity in
the effluent kept a steady rate for a volume of 200 ml9
A comparatively fáster elution was obtained on using
6E HNO, resulting in a non-defined peak3 The counting
rate of the effluent was constant over a long period of
1 ~\time, showing that the Ba was no longer eluted froa
the column.
IV«2. Adsorption of a misture of fission products on
1 7In this study a mixture of carrier-free Gs,
85Sr, 8 8Y, 14"4Ce and 133Ba tracer solution was psssed
through an ion-exchange column of sintered BaS0A at a
40
flow rate of 0o08 ml/min8 The eltitio» was earried succes-
si^sly with 30 mi eaeh of HgQ, 0.1M NaHO,, 0.1M M 0 , aaá
with 50 mi 6M HHO^8 2?h© effluent íraetions were coilseted
from eaeh run ana determines! quaatitati^ely by gassjaa spee=
trometrie analysis»
fhe resulta are shown by Figa 1?. Ihe percent ao~
tivity for each radioactif® traoer was eáiculated from the
área of the identified peai with respeet to the total
áreas of the same psak in the different fraetionsc As vm,ñ
espectedj the ^'Os and ^Sr aetivity were eluted with.
HgOs In the second run less than 1 of the Sr actiTity
was eluted with 0s1M NáNO, along with the partial acti^lty
of Y and ^ Ge® She remsindes3 of the yttrium &®,ñ, eeriiim
aetivity was completsly slutsd with 0,11 M O ^ solution
It was found that the ^ Ba oaa only partially be
from the column by eluting with 61 HNO^. The ^saa speetro
metrie analysis of the BaS0¿ bed showed that th©r© was no
traces of oontamination by the other isotopes,.
3» Fission produets group separation on BaSO« eolumn
An attampt was made to conduct a group separation of
aa aged fission produots solution by tasing ion=esohang©
eolumn of sintered BaS0.9 The solutioa n&m obtsined by
irradiating 1 g of t^Q, in th© JEN=»1 reactor with a neu-
trón flueney of 5«10^8 neutron/cs^» Ihe sample was left to
toIOX
"Ec
'É
12-
10-
8
6 -
c
ZJ
O 4"
0
0.1 M HN03
o
o
o
ó 0
0.1 M Na N03
48 64 80
Effluent Volume (mi)96
Pig. 16
KLution of carrier-free tracer activity
from sintered BaSO- column at a flow rate of
0,1 ml/min.
42
o
1 0 0 -
7 5 -
25 -
r\U
£O CM
ro x
O
-
CO > Üom
— OE *o
O Z
Ü CO > oO
roO
E ZOro ^
ü CO
•
>- üom
roO
"c. Zc Xif) S
CJ CO > OO
QD
-O O— COOCO °
GQ
-
Ok _
CO > Üoen
Eluted Radioisotopes
g 17
E l u t i o n of c a r r i e r - f r e e ^ 'Ga, ^ 88^ 144,Ce and
tracer activities in a standard mixture from
sintered BaSO» columnj 10 mm x 4.7 CE, at a flow
rate of 0908 ml/mine
43
cool for two years then dissolved in 10 mi 6M HN0^o The
solution was heated slowly to dryness and the solid was
dissolved, then diluted to 25 mi*
One mi of this solution plus 0s1 mi each of pSrs
Y and -^Ba were added to the top of the column which
was previously conditioned with watere ELution was car-
ried with 30 mi eaoh of water 0o1M NaN0^s 1M HNO^ and
then with 50 mi 6*31 HNO,S 3?he sepárate fractions were col-
lected and the identification of the various isotopes was
achieved by ^mma spectrometric analysiss The resulte are
summerized in Figo 18O
It can be seen that the majority of the present
tracers activity was removed by the water and 0Q1M
NaNO-, elution runs taking in consideration that th© pH
of the solution mixture was approximately 2 in nitric
acid» Upon elution with 0o1M HNO, no increase in the ac-
tivity of the effluent was observed and a second run was
carried by using 1M HNO, solutiona
It was noticed that the only contaminant for the
1 "í Q5 Q5
JJBa activity was the ^Zr~^Nb which was detected in
appreciable amount in the 6M HNO^ fractions and in the
solid BaS0.e For the separation of carrier free barium
isotopes from fission products solution^ the Zr~Nb ac-
tivitieshave to be removed from the mixture prior to
adsorption on the BaSO. columne Á better group separation
oro
O
100-"
75
44
roO
O
O
roO
roO
</) DQ
o 50-
25
0 _i T
o00Ik.
(f)
O
0000I
cei3
I
N
incvj
TXIC/D
ü0>ü
0000I
Xí00
0000I
N N
1roro
CQ N
roTa
ÜQ
1N
roroTo
OÜ
Eluted Radioisotopes
Pig. 18
Elution diagram of one year oíd Pission Products
85, and 133Ba tracer aotivitiessolution plus w>>Sr?
from sint ered 3aS0. column; 10 mm x 4»>7 cm. Flow
rate 0908 ml/mine
45
of the fission products activity on ion-exchange columna
of BaSO. may be achieved by adjusting the pH of the eluant
and/or by xising complexlng agents for the separation of
the trivalent isotope3e Q?he choice between the different
systems must await the resmlts of further studies»
46
1.
(1-z
0.
" / ¡o
(z)0.
0
)-
5
—
2
o.H
0.05-
= ] m i n -
] m i n -
o
Ti/2(exP) = 258 min.
o
0 30 6 0 90 120Time (min)
Fis. 19
Reaction in tiie system BaSO. (s)/*0e^+(aq)
Gonputer analysis to a two component ex—
ponential curve
47
V, APPENDIX I
COMPUTES ANALYSIS OF EXPERIMENTAL DATA BASED Olí A THREE
EXPONENTIAL SYSTEM
A Fortran V programme for the Univac-1106 has been
used for the analysis of the experimental data of the het-
erogeneous ion exchange reactions (5)* When th© graphical
presentation of the data on a semi-logarithmic scale
yields a curve composed of two exponentials? the follow-
ing equation can be theoretically appliedo
y = (1-z) e"UaS + Z&e~°v*x (1)
wherei
j is the counting rate in tha solution?
x is the reaction time (min)o
In this case9 the £? u and v are the unknown pa-
rameters to be eomputed by the programme»
On computing the experimental data of the reac-
tion in the system BaSO.(s)/ *Ce^+(aq), the produced re-
sulta differed to a great extent from the experimental
curve, Fige 19» Actually, the ti valué, which corresponds
to the fast reaction eoincided with the programme result
but no approximation could be obtained for the Ti valué»
The erroneous resulta obtained by the analysis of the
two exponential system were thought to be due to the
48
presence of a third component. In this case, equation (1)
can be written as followss
y = Aoe + B.e + C e \¿)
where: A, B and C represent the three normalized compo-
nent s valúes at x = 0.
A + B + C = 1 (3)
In order to utilize the programme written for the
two exponential curve to analyse a three component system?
the following procedure has been appliedo
1o A time valué xQ is selected at a point on the curve
which will elimínate the first componente i«ea the very
fast reactione Equation (2) is then reduced to:
y = Bae"?oS + C.e~v'eS (4)
since, A8e"UoX = O for x xQ
2. By applying the coordinate transform corresponding to
the translation from (10 ; 0,5) to (O ; 1) to the data
in column I9 Table V9 the new set of data in column II
is obtainedo As a result of the programme treatment of
these data, the G and v1 parameters of the third com-
ponent can be calculatedo
3» By subtracting the third component valúes from the
experimental data, column III, and applying the co-
ordinate translation from (O ; 00812) to (O ; 1), the
SáBLE IV
Analysis of the Experimental Data by a Tbree Exponential System
I
* i
0
2
46
10
1520
30
60
120
240
no0«42
0o31
0o290.250.230.200.180.16
0.140.10
—
—
__
0
510
20
50
110
230
0
I I
" x o
10) (yo=0.25)
—
_.„
1.0
0.920.800o72
0.64Oo56
0o40
= 001888 = 2,4.10-3
" X "
0
0
0
0
0
0
0
I I I
~ C e - v S x
i .
O812
.232
.122
.102
o 062
o 042
O012
—
—
—
gy^=s
1 .
0 o
0 .
0 .
o00 o
0 o
A =u =B =V =
I V
y¿1-0
0
285150
125
076
051
041
—
—
0.659• 0,935
Os153
: OeO89
A a í
0a
0.
0.
0 .
-
I B
69510
015002
a m a
. _
. _
. _
—
V
Be-vxi
Oe1530.1280a1070.0890.0630.040
OsO250.010
—
——•
- T ' XOe i
00188
001870 O 1 8 6
0.185C1830.1800.178
0.1730.1590.1350.097
50
/L
1.0
A-
0.5H
0 .3 -
0.1
0.05-
0.03
-t1/2= 0.7 min.
r1/2= 8 min.
T1/2 = 252 min.
0 30 60 90 120Time (min)
iCo 20
Reaction in the system BaS0^(s)/*0e^+(aq)
Gora-DUter analysis to a three oomponent exponential
curve
51
data set for the short and intermedíate components is
provided, coluran IV. In tliis case equation (2) is re-
duced to
y = A«.e"u'x + B'oe"^x (5)
By computing these data? the valúes of A, B$ u and v
can be obtained by simple manipulation of the resultSc
4e Finally, the substitution of the component parameters
A¡ B, Cs u, Y and vs in equation (2)9 provides the
analytical expression for the best fitting curvee The
valúes for each component are tabultated in column ?s
By applying these steps to the analysis of the ex-
perimental data? a curve was obtained which coincided
with the original points, Pigo 20,
53
Vio ACKNOILEDGEMENT
One of the authors, So Allam? wishes to offer her
gratitude to the Spanish Institute of Nuclear Studies
for the support and working facilities provided during
the conduct of this work at the Junta ele Energía Nuclear
in Madrid© Appreciations are equally extended to th©
International Atomic Energy Ageney and the Egyptian
Atomie Energy Establishment for granting th® fellow-
ship and the permission to publish this reporto
55
VII. REFERENCES
(1) Barrachina, HL and Sauvagnac, R.; CeEoA» Rep*NS 2166 (1962).
(2) Kraus, A., Harold, 0. and Nelson, F.; "Radio-isotopes in th.e Physical Science and Industry5*IAEA, Vola III (1962) P. 387.
(3) Lieser, K. H. and Hild, W.; ibid, P. 337»
(4) Kar, K, R8f Singhj G» and Jain, SoC9j Mikrochim,
Acta, ¿, 614 (1968).
(5) Allam, Se, Barrachina, M9 and Aparicio, £.;
JEN, 288 (1974).
J.E.N. 289
Junta df Lnergía Nuclear, División de Química, Madrid"Intercambio heterogéneo de iones isotópicos y
no-isotopicos en la superficie del sulfato de bario"Parte II. - Cinética y Aplicaciones.ALLAñ, S . y BARRACHINA, « . (1974) 55 pp. 20 í i g s . 5 r e f s .
Se estudia el mecanismo de intercambio o de adsorción de los iones Cs ' ,
?*, Y , Ce^ y Cr^ en el S0/(Ba. Cl número de iones Ba^ intercambiables, tan
lo en el S0/,Ba sinterizado como en el obtenido directamente por precipitación,
aumenta con la temperatura.
En las reaccionas de intercambio no-isotópico, llevadas a cabo con ambos t i -
pos de sólidos, la presencia de iones I r o Na- en la fase líquida inhibe la ad-
sorción de los cationes por la fase sólida. Cs de destacar, no obstante, que los
a
J.E.N. 289
Junta de Energía Nuclear, División de Química, Hadrid
"Intercambio heterogéneo de iones isotópicos yno-isotopicos en la superficie del sulfato de bario"Parte II. - Cinética y Aplicaciones.ALLAH, S . v BARRACHINA, M. (1974) b5 pp. 20 l i g s . b r e í s .
Se estudia el mecanismo de intercambio arle adsorción de los iones Cs , Ga ,Sr?-, ) '•, Cr- • \ & '•=• en el S0;(Ba. t i número de iones Ba^ inIorcarabíablos, tanto en r l S0/,Ba sintei-i/ado como en el obtenido di reclamen le por precipitación,aumenta con la temperatura.
En las reacciones de intercambio no-isolópico, llevadas a cabo con ambos t i -
pos d>, sólidos, la presentid dt iones II o Na en la fase líquida inhibe la ad-
sorción df, los cationes por la fase sólida. Es de deslacar, no obstante, que los
J.E.N. 289
Junta de Energía Nuclear, División de Química, Hadrid.
"Intercambio heterogéneo de iones isotópicos yno-isotopicos en la superficie del sulfato de bario"Parte II. - Cinética y Aplicaciones.ALLAH, S. y BARRACHINA, H. (1974) b5 pp. 20 f i g s . 5 r e f s .
Se estudia e] iiBcanismode intercambio o do adsorción de los iones Cg-, Ba ,
f , Ce * y Co1^ en el S0¿Bd. El número de iones Ba^ intercambiables, tan
to en el S0/(Ba sinIeri7ado como en el obtenido directamente por precipitación,
aumenta con la temperatura.
En las reacciones de intercambio no-isotópico, llevadas a cabo con ambos t i -
pos de sólidos, la presencia de iores H" o Na" en la fase líquida inhibe la ad-
sorción de los caliores por la fase sólida. Cs de destacar, no obstante, que los
J.E.N. 289
Junta de Energía Nuclear, División de Química, Hadrid
"Intercambio heterogéneo de iones isotópicos yno-isotopicos en la superficie del sulfato de bario"Parte II. - Cinética y Aplicaciones.ALLAM, S. y BARRACHINA, M. (1974) 55 pp. 20 figs. 5 rofs.
Se estudia el nvcanismo de intercambio o de adsorción de los iones Cs , BaSr?''', Y \ Ce^ y Cp'1^ en el StyBa. El número de iones Ba^ intercambiables, tanto en el S0/,Ba sinlerizado como en el obtenido directamente por precipitación,aumenta con la louneralura.
En las reacciores de intercambio no-isotópico, llevadas a cabo con ambos t i
pos di¡ sólidos, la presencia de iores l l ' ' o Na- en la lase líquida inhibe la ao-
sorción de los cationes por la fase sólida. Es de deslacar, no obstante, que los
d i '
i i'iddin " ' ni 'i b'uhr, nnr ambo» Mpo, d.1 oMdo , min i l r 1 lo-,
i j . ' i p ' i < S O Í I R n i ] , i d o ,
iMj' H ' in in 'od ' lo-, IH ' I I monuvdh'nl c" . d í / d l o n l i j ; y I r Na I uní f s , d v n
d1- i .-iOM o ín1 (i"> ambin t >>rt , ! SÜ/jBa i>inIi jri7aüa, os sulicii>nl.enii;iilx
ronm para [ l um i i l i i su .I parat iú i i un
Ii i i ' 'uní ' d i l i i l i p e dinb'j' l i n o Ji
i T i • <¡ < , 30¿,B . i n ' i I ' f O ' j .
I I conipor'ainn'ii'o di los io ius monona I t'n'i ° , d i u k n l i ' s / t r i . a l i '
ti a la ad cn"- ión o i r 1 . >ambio con i l SO;,Bd s i n l i i i ado, . n "p i t
oí Ir T I 1 f romo nara p e r m i l i r SJ SHparacio', c i grupo1,
lo , im • 11' r •• l o - .
i oíH '. C. '' JOII tánidarai jnl( adsorbido. por ambtu l i pos di1 só l idos, mientra-, l o ;
iones i 1 ' ' i ' ) por i-1 S O ^ B i ' i n U í i/ado»
Ll comporlaraionlo é 1 los iorr 's mono\alentó?, d i v a l c n l i s y t r i v a l c n l o s , fren
l e a l a adsorción u i i i t m a m b i o ton L I SO;(Ba s i n l i r i / a d o , os suficionfornenfi•d i f ' T e n l o romo paiv. p i r m U i f &u M jpar'ación ^n griipot..
Ion •- C ,on i auidami jnln adqoibido por arabos l ipos dfj °ó l i dos , míen i ra ' l o ,i on i s > ó lu poi ul SOÍ(B; , i n l i i i /ar lo .
f l coimorlaniienlo de lob ionrs mono a l r n l c s , el i va 1 en I r < / t r i valcnlrc . fren
i ' 1 a la adoOtíion o ínter' arabio con ul S0/(Ba s i n l t i i / a d o , i s s u l i i ii'iilemcnl i
di t i ren l i c orno para pur inHi r °'i sepaiar ión en grupo r ,
J.E.N. 289
Junta d¡¡ t.iiergia Nuclear, División de Química, Madrid
"Heterogeneous iso top ic and non- i so top ic ion
eX'.:b.ange on the siirfaee of barium sulfate"Part II» -> Kinetics and Application.
AL! AM, S. and BARRACHINA, M. (197'I-) 55 pp. 20 f igs . 5 refs.
Inri m lidian i sin of the isutopic aod non-isotopic ion exchange of Cs , Ba~",
S¡••'*, )•'•'", C«°T.and C¡:M cations in the presence of sol id BaSO , is discussed.
Tho numbep of exchangeable Ba~" ions on ihe surface of sintered and unprocessed
BaSO/,. increasus with temperature up to 7Ü°C.
In thi non-isotopic exchange reactions carried with both types ot sol Id, the
preseñe» oí H* or N-.-T ions in the l iquid phase usual!y inhibi is the sulid a f f i -
n i t y tur thn di Hvrent cations,, I t i i le thr; CB-^JOIT. rapidly exchange with both
J.E.N. 289
-l'.'nta df Lm-irgía Nuclear1, D iv i s ión de Química, Madrid"Heterogeneous isotopic and non-isotopic ion
exchange on the surface of barium sulfate"Part II,, - Kinetics and Application.
ALLAM, S. ari-J BARRACHINA, M. (1974) % pp. 20 f i g s . 5 r e f s . L
íhtí iii.ichanisin oí" tho isotopic and non-isotopic ion exchange of Cs', Ba ,
$rK>, ''••'*, C¿:';" and CiiH';* cations in the prftsonce of sol id BaS0¿(. is discussed.
The: number of uxchang^dbln B;-i?r ions on the surface of sintered and unprocessed
B;--.SO¿!. incr'da:-".':.s with tfiinpt;ratiiry up to 70°C.
in tl'K: noii-isotopic'éxchangt! reactions carried with both types of so l id , tl>:
p re sonó; of H" oí1 N;-íl!.ions in the l iqu id phase usually inhibits the so l id a t f i -
n i tv íor th" drfft.-rwnt cations. ílhile the Ce^.ions rapidly exchange with both
J.E.N. 289 J.E.N. 289
Junta d'-. tnergía Nuclear, División de Química, Madrid"Hete rogeneous isotopic and non- i so topic ion
exchange on the surface of b a r i u m sulfa te"P a r t 1L •- Kinet ics and Appl icat ion.ALLAM, S. and BARRACHINA, M. (1974) 55 pp. 20 f i gs . 5 reís.
Ihe iiiechanism oí th : isotopic and non-isotopic ion exchange of Csv, Ba'-',Sr'-1", Y'"-, CÍ!1^ and Cu''1"" cations in the presence of sol id BaSO;,. is discussed.Ihe mimber of exchangeable Ba'-' ions on the surface of sintered and unprocessedBaSO/j. inci'Kases with temperature up to 70°C.
In the non-i so topic exchange reactions carried with both types of sol id, thspreseno; of tí'-' or Na' ions in the l iquid phase usually inhib i ts the solid a f f i -
nity tur tho difíereír!: cations, While the ions rapidly exchange with both
..'•.,ni:a d>; Energía Nuclear, División de Química, Madrid"Heterogeneous isotopic and non-isotopic ion
exchange on the surface of barium sulfate"Part II, - Kinetics and Application,ALLAM, S. and BARRACHINA, M. (197'ij 55 pp, 20 f igs . 5 refs.
Ihe iiBchanism ot the isotopic and non-isotopic ion exchange of Csv, Ba ,S r ^ , Y:'''', O"''-" and &M cations in the presence of solid BaS0/( is discussed.l'hi; '"i.Kiib'u1 üf exchangfiabl,-; Ba'-+ ions on the surface of sintered and unprocessedBr¡SO;, !ncr«a:--:s with temperatura up to 70°C.
In the non-isLÚjpic exchange reactions carried with both types of so l id , thepresencr of H" or N:-,:'\ions in the üquid phase usually inhibits the so l id a f f i -
ni tv 'o¡' thu cnffiírí-ip-!. cations. Whí'le the CB'-Í-Í- ions rapidly exchange with both
•• vt i n i i i i l i d , l h Y ' 1 i f i t ; j irr 0 " b l a p l m v d b/ i. I, • i\nl i > el üaSO/,.
l i l i i iHi • x i j iang. ' b " h a , i o . i r u l Hit, inunoval T IL , b i v a l e n ! and L r i v a " m l .i.dl ions on thi s i n l i ' n d BaSÜ^ p . f f i ü k n l l y ¡ l i l i i n 1 i n aq i O Í S and a c i ds o l . i l i o n s l o a l l u w s i m p k gi'o 10 s " i acal i o n .
[\P<K of sol Id, th'¡ ) ' ' 1 ' i MI. anj only capliired by tho sinlurod DaSO/,.
n., "¡3n '•'xchangK Doha.ioiir ol Lhu rnonovalonl, bivalonl and I r ival un t
ia ' 'oni , on | l i i ^inlcred BaS0/h is suífecionlly difforent in aqucous and acidrú\ Mons tn aMow siraph 9^041 soparalion.
ni
lype of sol i d, the VJ' ions aro only captured by Ihu sintun'd BaS0¿r
The ion exchangs behaviour of Iho monovalenl, b iva lml and I r i vahnt
calions on thc sintored BaS0;( is sufíccionilv dif ieren I in aquoous and acid
solulions lo allow simple group separalion.
ivpcs of sol id , Ihc Y0-' iore are only caplurcd by Ihn sinlurcd BaS0;(.
The ion exchange buhaviour of Ihe monovalenl, bivalcnl and l r i val cni
calions on thc sinlercd BaSO/, is suffecionlly di f fercnl in aqueous and acid
ruliiHops lo allow simple group separalion.
