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Aqueous systems at high temperature—VII
J. lnorg. Nucl. Chore.. 1962, Vol. 24, pp. 995 to 1000. Pergamon Press Ltd. Printed in Northern Ireland
AQUEOUS SYSTEMS AT H I G H T E M P E R A T U R E - - V I I LIQUID-LIQUID
IMMISCIBILITY AND CRITICAL PHENOMENA
IN
T H E S Y S T E M S U O 3 - S O s - H 2 0 , UO3-SO:~-D20 A N D C u O - S O 3 - D 2 0 , 270-430°C*(l) WILLIAM L. MARSHALL, ERNEST V. JONES, G. M. HEBERT and F. J. SMITH Reactor Chemistry Division Oak Ridge National Laboratory Oak Ridge, Tennessee (Received I Fehruarv 1962)
Abstract---In the condensed systems UOu-SO3-H20, UO3-SO3-1320 and CuO-SOu-D20 boundary limits of liquid-liquid immiscibility were extended to compositions at which L1 == V =:=supercritical fluid at several fixed concentrations of SOu. These (isothermal) critical end points were found at temperatures between 374 and 430C with sohttions having molal ratios, mm~t~mco~io~: mso3, between 0.20 and 0-50 depending upon the concentration of SOu in the systems. A second liquid phase was not observed at lower 1-nolalratios. Instead, critical phenomena (in this paper used to designate the disappearance of the meniscus between liquid and vapour phases and not to specifythe appearance of a second liquid phase) revealed concentrations of UO3 or of CuO as high as 0.25 molal in a supercritical fluid SO:3 D20, 1.0 molal in SOu. These observations coincided with those made previously which showed an appreciable solubility of the NiO component in the supercritical fluid SOu-H.,(). PREVlOUS investigations o f l i q u i d q i q u i d immiscibility in the systems U Q SO~--H~O and UO3-SO,~ ~ D,~O at high t e m p e r a t u r e have disclosed (1) b o u n d a r y limits o f temperature and c o m p o s i t i o n for stoicheiometric UO2SO ~ in H 2 0 and D oO, m,3) (2) some b o u n d a r y limits for solutions o f m o l a l ratio, m c % : m s % , varying from 0"33 to 1-2. (:/~ and (3) c o m p o s i t i o n s o f the heavy a n d light liquid phases in equilibrium. I~) A n o t h e r investigation has disclosed b o u n d a r y limits o f l i q u i d - l i q u i d immiscibility for the systems UO,.,SO~ H ~ S Q - H 2 0 , CuSO4 H 2 S O t H.~O, and UOoSO 4 CuSO4-H2SO 4 H=,O at molal ratios, (rob-% + m c , o ) : m s % , varying from 0"72 to 1'00.15) I n earlier work. Sr(:oY observed a solubility o f U Q S O a in super-critical H 2 0 containing low concentrations o f H.,SO4.16) The p u r p o s e o f this present investigation was to extend the d e t e r m i n a t i o n o f phase b o u n d a r i e s in the condensed systems to a wider range o f SO 3 concentration and to molal ratios, mu% :ms% o r inca o :m~%, designated R b- and R e , , respectively, as k)~ as 0. l at t e m p e r a t u r e s from a p p r o x i m a t e l y 300 ° to critical t e m p e r a t u r e s (whereL~ V). F r o m the observations o f SEcoY and from e x t r a p o l a t i o n s o f earlier two-liquid phase d a t a to t e m p e r a t u r e s near 400 ~, it was expected that c o m p o s i t i o n s at which L 1 V * This paper is based on work performed at Oak Ridge National Laboratory, which is operated by Union Carbide Corporation for the Atomic Energy Commission. ~ Previous paper in series: "hwest('~,ations on the System NiO--SO3-H20 and its DzO Analqg, ue/i'om 10 ~ to 2 m SOs, 150-400°C. '' W. L. MARSHAH.,J. S. Girl. and R. SIUSHER,J. hlorg. Nttcl. ('hem. In press 11962). '~' C H. SEcov, J. Amer. Chem. Soc, 72, 3343 (1950). ':' n. F. McDtIFVlE,Review in Fluid Fuel Reactors (Edited by J. A. LANE, H. G. MACPHEI~.St)N.[. ~'~ASLAN)pp. 85-127 Addison-Wesley Reading, Mass. (1958). '~' [!. V. JONESand W. L. MARSHALL,J. Ino~g. Nucl. Chem. 23, 287 (1961). ':~ l-:. E. CLARK.J. S. Gmc, R. SLUSHERand C. H. SECOY,J. Chem. Engp{~. Data, 4, 12 (1959). C. H. SECO¥, Report ORNL-607, pp. 33-38 11949). 995
996
W . L . MARSHALL,E. V. JONES,G. M. HEBERTand F. J. SMITH
super-critical fluid w o u l d be f o u n d i n d i c a t i n g a p p r e c i a b l e solubility o f UOa a n d C u O in supercritical fluids S O 3 - H 2 0 a n d S O 3 - D 2 0 . I n a d d i t i o n to being o f f u n d a m e n t a l interest, the phase b o u n d a r y i n f o r m a t i o n on the systems c o n t a i n i n g u r a n i u m w o u l d be useful in specifying o p e r a t i n g limits o f t e m p e r a t u r e a n d c o m p o s i t i o n f o r a q u e o u s h o m o g e n e o u s r e a c t o r fuels. I n f o r m a t i o n o n systems c o n t a i n i n g c o p p e r w o u l d be useful since c o p p e r has been included in fuel c o m p o s i t i o n s as a catalyst for the r e c o m b i n a t i o n o f radiolytic Ha a n d 02. (37 The o p e r a t i n g t e m p e r a t u r e s o f a q u e o u s h o m o g e n e o u s reactors m i g h t be extended a b o v e 370 ° b y using fuels o f c o m p o s i t i o n s showing critical p h e n o m e n a b u t no phase changes a t c o n s i d e r a b l y l o w e r temperatures. The v a p o u r phase c o u l d be eliminated at all temp e r a t u r e s b y m a i n t a i n i n g a h y d r o s t a t i c pressure on the system greater t h a n the critical pressure. This p a p e r presents some l i q u i d - l i q u i d immiscibility limits o f t e m p e r a t u r e a n d c o m p o s i t i o n as well as some t e m p e r a t u r e s for critical p h e n o m e n a in the systems UO3-SOz-H20, UO3-SO3-D20, and CuO-SOz-D~O. EXPERIMENTAL PROCEDURES The preparation of stock solutions of UO3 or of CuO dissolved in H~SO4--H20 or D2SO4--D20, and the chemical analyses for UO z, CuO and SOa were performed in the manner described previously.~4,7~ The source of the UOa'H20, H2SO4, and D20 reagents was the same as for the previous work although the D20 was found by an improved analysis to contain only 0-3 ~ H20 instead of 2 ~ reported previously. Experimental runs by the synthetic method were carried out in the type of apparatus described elsewhere~8) using quartz capillary tubes which contained solutions of known compositions. Supersaturation by the heavy liquid phase was not observed. The absence of supersaturation in experiments conducted previously(Z,5,8) indicated that no supersaturation was to be expected in these experiments. Appearance of immiscibility or critical phenomenon was instantaneous at temperatures defining the phase boundary limits. The tubes containing solutions were filled 40-50 per cent full at 25 ° and at final temperatures were from 50-90 per cent full. RESULTS AND DISCUSSION E x p e r i m e n t a l d a t a given in Tables 1, 2 a n d 3 are s h o w n g r a p h i c a l l y in Figs, 1, 2 a n d 3 for the systems U O 3 - S O a - H 2 0 , U O a - S O 3 - D z O , a n d C u O - S O z - D 2 0 , respectively. TABLE 1.--TEMPERATURES( ° C ) FOR THE APPEARANCE OF LIQUID-LIQUID IMMISCIBILITY AND CRITICAL PHENOMENA IN THE SYSTEM U O a - S O a - H a O ; Molal ratio mt, oJms%
0.2000
SO3 ( m o l a l i t y ) 0.1000 0.0500
1.000 0.950 0.900 0.800 0.750 0.700 0.600 0.500 0.400 0.300 0.250 0.2000 0.1000 0.0000
298.0L* 301.5L 306.8L 316-0L -325.0L 334.2L 344.6L 357'5L 370.0L -380C -380C
308.9L 312.2L 316.3L 324.8L -331.5L 340.0L 348.8L 358'3L 368.5L -377LC(?) -379C
321.0L + S -327.0L + S 333'6L -340.6L 348.2L 356.0L 363.0L 370.4L -378C 377C --
0.0200 < 350S -<350S -351.8L -357-8L 362.8L 368-4L 375LC(?) 374C ----
liquid-liquid immiscibility, C = critical phenomena, S = solid phase (presumably UO3 hydrate) (71 E. V. JONESand W. L. MARSHALL,J. Inorg. Nucl. Chem. 23, 295 (1961). ~8) C. J. BARTON,G. M. HEBERTand W. L. MARSHALL,Y. Inorg. Nucl. Chem. 21, 141 (1961).
* L =
997
Aqueous systems at high temperature--VII TABLE2.--TEMPERATURES(°C) EOR THE APPEARANCEOF LIQUID-LIQUID UOa-SOz-D20;
IMMISCIBILITY AND CRITICAL PHENOMENA IN THE SYSTEM
Molal ratio
SOa (molality)
I/1U03] 'IIISO 3
1.000 0.800 0.600 0.500 0.400 0-300 0.2000 0-1000 0-0000
1.000
0.800
0-600
0.364
0.2000
0.1000
0.0500
0.0200
277.5L* 306.3L 341.8L 360.5L 378.7L 396C (0-59)t 399C (0'61) 402C (0.61) 408C
277.8L 299.2L 332.7L 355.5L 375.8L 378C (0-62) 396C (0'52) 399C (0.51) 400C
278.5L 301-2L 331.0L . . 367.8L 383.6L . . 392C (0"50) 395C (0.43) 392C
28 I.OL 302.6L 328.2L . . 358.7L 375.2L . . . 383C (0'49) 383C (0-49) 384C
287.8L 306.8L 329.2L . 3593L -. . 380C (0"44) 377C (0.53) 379C
297.4L 315.5L 332.5L
313.0L 328.0L 343.3L 352.3L 362.5L 374C (0.48) 373C (0"48) 373C (0.52) 373C
31 IS 337.7L 352-0L 358-7L 365.0L 373(' (0.47) 373( (0-48) 374C (0.50) 372C
354-5L -375C --k_ 376C
* L - : liquid liquid immiscibility, C -- critical phenomena, S ~ solid phase (presumably UOa hydrate), ? Value in parentheses = density of supercritical fluid at temperature. ]'ABLE 3 . - - T E M P E R A T U R E S ( o f ) FOR THE APPEARANCE OF LIQUID-LIQUID IMMISCIBILITY AND CRITICAL PHENOMENA 1N THE SYSTEM C u O - S O a - D e O ;
Molal ratio mcu°Pns°a 1 "000
•800 -700 "600 -500 •400 •300 •2000 •1000
SO~ (molalit},)
1000 S*
326L 347/. 367/. 384L 408L 428L 422C 415C
0.800
0.600
0.364
0.2000
0.1000
0.0500
0.0200
S
S
S
S
S
S
S
325L 341L 363L 381L 400L 419L 411C 406C
S 350L 361L 373L 385L 397/. 393C 391C
S 336L 352L 367L 381L 389C 387C 385C
S 334L 354L 372L 381C 380C 379C 379C
S S 360L 378L 377C 376C 376C 376C
S S S 374C 374C 373C 373C 373C
S S S S 373(7 373C 373(" 372C
* L = liquid-liquid immiscibility, C -- critical phenomena, S 2CuO-CuSO4-2DeO)
blue green solid (presumably
T h e s y m b o l ( ! S) u s e d in T a b l e l indicates a small a m o u n t o f solid f o r m i n g at t e m p e r a t u r e s s o m e w h a t b e l o w those r e p o r t e d for l i q u i d - l i q u i d immiscibility. T h e c o m b i n e d s y m b o l s LC(?) designate a n a p p a r e n t l y s i m u l t a n e o u s a p p e a r a n c e o f s e c o n d liquid phase a n d critical p h e n o m e n o n . W h e r e o n l y the s y m b o l S is given b u t n o t e m p e r a t u r e is r e p o r t e d a solid phase a p p e a r e d at t e m p e r a t u r e s c o n s i d e r a b l y b e l o w those for l i q u i d - l i q u i d i m m i s c i b i l i t y or critical p h e n o m e n o n . Also i n c l u d e d in Fig. l are s o m e l i q u i d - l i q u i d i m m i s c i b i l i t y t e m p e r a t u r e s i n t e r p o l a t e d f r o m the d a t a o f CLARK et al. (a~ E a c h curve represents phase b o u n d a r y c o n d i t i o n s o f t e m p e r a t u r e a n d c o m p o s i t i o n expressed as m o l a l ratios R U a n d R c u for initial c o m p o s i t i o n s c o n t a i n i n g a fixed c o n c e n t r a t i o n o f SOa, specified for each curve. There are two phase b o u n d a r y regions s h o w n l b r each s y s t e m - - t h a t o f l i q u i d - l i q u i d i m m i s c i b i l i t y a n d t h a t o f critical p h e n o m e n o n . F o r a fixed c o n c e n t r a t i o n o f SOa the two curves r e p r e s e n t i n g these b o u n d a r i e s intersect at a n (isothermal) critical e n d p o i n t where the c o m p o s i t i o n o f the light-liquid phase (L 0 - - v a p o u r phase (V) supercritical fluid. T h e c o m p o s i t i o n s o f h e a v y liquid phases (L2) which first a p p e a r in the systems U O a - S O a - H , O a n d
W. L. MARSHALL,E. V. JONES,G. M. HEBERTand F. J. SMITH
998
I
41o
SUPERCRITICAL 400 __FLUIDREGION
I
ISTUCKEY,SEC0'I 390 - - f i I
I
/CRITICAL PHENOMENA
REGIONOF
_----~ _ _ _ _ =
IMMISCIBILITY
~
350
PRECIPITATION
L ^ ^e I ~ o
w 340
\
330
"% OF SOLID
~ PHASE
o., ~ . .
REG,0N OF
UNSATURATED SOLUTION
320
~
3,0
m.,.@ FROMDATAOFCLARK,e t o l
~
300 290
i
0
O',
0"2
0'3
0"4
0"5
0"6
0'7
0'8
0"9
1'0
muo3/ms03
MOLAL RATIO,
F1G. 1.--System UOa-SO~-H20, liquid-liquid immiscibility and critical phenomena. SUPERCRITICAL FLUID REGION
420
410
.f
CRITICAL PHENOMENA
400
~ 390 I ..... 380 ~
~
i,
"*",,,~
S03,m ~.I'0
k,.~. ~-~, ="~ ~-'%~ ~ i I. . . . .
~ _ _ _ _ --00""86
}---
),,=..., ~ . . . . . 370 ~
REGION OF LIQUID-LIQUID IMMISCIBILITY
-0"36 ~ 0.05 -0"2
~ . ~
360 !
g ~o
,~
340
~ X~
o.
~
~
330
PRECIPITATION
OFSOLID PHASE r"-.
-\
~
320
300
REGION OF 290
UNSATURATED
SOLUTION
280 270 0
0"1
0'2
0"3
0.4
O'S
0"6
0-7
0"8
0"9
t-0
MOLAL RATIO, muo 3 /mSO 3
FIG. 2.--System UO~-SOa-D~O, liquid-liquid immiscibility and critical phenomena.
999
Aqueous systems at high temperature--VII
i
I
L SUPERCRITICAL 450 I--FLUID REGION --
440
1
!
1
i
ITICAL
,
,
[
[
|PHENOMENAl
[
430
420
410
400
g FbJ (2. bJ F-
390 380 370 360 350 340 330 320 0
0-1
0"2
0o3
0-4
0"5
MOLAL RATIO,
0"6
0'7
0"8
0"9
90
mcuo/mso 3
FiG. 3.--System CuO-SOa-D~O, liquid-liquid immiscibility and critical phenomena. U Q - S Q - D z O as the temperature is raised can be estimated from the data previously reported on equilibrium compositions with light-liquid phases. (4) In Figs. 1-3 the molalities are the molalities of the solutions introduced into the tubes, these solutions being L 1. For the dashed curves, which report the temperatures of the critical phenomenon of L 1 and V, the molalities represent also the molalities of L and V at the reported, apparent critical temperature. However, the true critical temperature (where L -- V) can be determined only at a volume filling of L 1 of 50 per cent at temperature. The actual fillings at final temperatures in most instances were larger than 50 per cent. But upon comparing some densities of the supercritical fluids in Table 2 (obtained from the densities at 25 ° and the liq uid: total-volume ratios) with those of pure D20 near its critical temperature, (9) and considering the higher densities of the solutions, the reported temperatures are believed to approximate rather closely the true values. Fig. 1 shows, in addition, some interpolations from critical temperatures obtained by SECOY and STUCKEYfor solutions of HzSO4-H20 at RU == 0 and at a final liquid-volume filling of 50 per cent. (l°) For the curves representing the appearance of L,, the composition of L 1 at the (9, G. M. HEBERT, H. F. McDurr~E and C. H. SEcoY, J. Phys. Chem. 62, 431 (1958). ,1.) j. E. STUCK};Y. Ph.D. Dissertation, The University of Oklahoma Graduate College, N o r m a n , Oklahoma (1957).
I000
W.L. MARSHALL,E. V. JONES,G. M. HEBERTand F. J. SMITH
recorded temperature will vary somewhat from the initial composition with variation in the percentage of filling. It was shown previously, however, that in the system UOs-SOa-H20 the immiscibility temperature was little affected by moderate changes in this percentage of filling. ~s~ At high concentrations of SOs the addition of UO s lowers the critical temperature. This may arise from a higher degree of association of UO2SO ~ than of H2SO4; thus as UO a is added a decrease in concentration of ionic species lowers the critical temperature. As more UO3 is added R E increases sufficiently that upon raising the temperature of the system liquid-liquid immiscibility rather than a critical phenomenon (L = V) is observed. For the system CuO-SOs-D20 at constant molality of SO s the addition of CuO component invariably raises the critical temperature (Fig. 3). Therefore CuSO 4 at these temperatures may dissociate to a greater extent than D2SO 4 and thus raise the critical temperature. From Figs. 2 and 3 it is seen that UO a and CuO are soluble up to a concentration near 0.3 molal in a supercritical SOs-D20 fluid which is 1.0 molal in SO s. These observations and a similar one on the system NiO-SOs-H20 (but near 0.1 molal NiO in 1.0 molal SOs) m indicate that other metallic oxides may show high solubilities in the supercritical fluids SOa-HoO and SOs-D20. Acknowledgement The authors thank Professor J. E. RleCI,New York University, for his constructive review of the manuscript.
AQUEOUS SYSTEMS AT H I G H T E M P E R A T U R E - - V I I LIQUID-LIQUID
IMMISCIBILITY AND CRITICAL PHENOMENA
IN
T H E S Y S T E M S U O 3 - S O s - H 2 0 , UO3-SO:~-D20 A N D C u O - S O 3 - D 2 0 , 270-430°C*(l) WILLIAM L. MARSHALL, ERNEST V. JONES, G. M. HEBERT and F. J. SMITH Reactor Chemistry Division Oak Ridge National Laboratory Oak Ridge, Tennessee (Received I Fehruarv 1962)
Abstract---In the condensed systems UOu-SO3-H20, UO3-SO3-1320 and CuO-SOu-D20 boundary limits of liquid-liquid immiscibility were extended to compositions at which L1 == V =:=supercritical fluid at several fixed concentrations of SOu. These (isothermal) critical end points were found at temperatures between 374 and 430C with sohttions having molal ratios, mm~t~mco~io~: mso3, between 0.20 and 0-50 depending upon the concentration of SOu in the systems. A second liquid phase was not observed at lower 1-nolalratios. Instead, critical phenomena (in this paper used to designate the disappearance of the meniscus between liquid and vapour phases and not to specifythe appearance of a second liquid phase) revealed concentrations of UO3 or of CuO as high as 0.25 molal in a supercritical fluid SO:3 D20, 1.0 molal in SOu. These observations coincided with those made previously which showed an appreciable solubility of the NiO component in the supercritical fluid SOu-H.,(). PREVlOUS investigations o f l i q u i d q i q u i d immiscibility in the systems U Q SO~--H~O and UO3-SO,~ ~ D,~O at high t e m p e r a t u r e have disclosed (1) b o u n d a r y limits o f temperature and c o m p o s i t i o n for stoicheiometric UO2SO ~ in H 2 0 and D oO, m,3) (2) some b o u n d a r y limits for solutions o f m o l a l ratio, m c % : m s % , varying from 0"33 to 1-2. (:/~ and (3) c o m p o s i t i o n s o f the heavy a n d light liquid phases in equilibrium. I~) A n o t h e r investigation has disclosed b o u n d a r y limits o f l i q u i d - l i q u i d immiscibility for the systems UO,.,SO~ H ~ S Q - H 2 0 , CuSO4 H 2 S O t H.~O, and UOoSO 4 CuSO4-H2SO 4 H=,O at molal ratios, (rob-% + m c , o ) : m s % , varying from 0"72 to 1'00.15) I n earlier work. Sr(:oY observed a solubility o f U Q S O a in super-critical H 2 0 containing low concentrations o f H.,SO4.16) The p u r p o s e o f this present investigation was to extend the d e t e r m i n a t i o n o f phase b o u n d a r i e s in the condensed systems to a wider range o f SO 3 concentration and to molal ratios, mu% :ms% o r inca o :m~%, designated R b- and R e , , respectively, as k)~ as 0. l at t e m p e r a t u r e s from a p p r o x i m a t e l y 300 ° to critical t e m p e r a t u r e s (whereL~ V). F r o m the observations o f SEcoY and from e x t r a p o l a t i o n s o f earlier two-liquid phase d a t a to t e m p e r a t u r e s near 400 ~, it was expected that c o m p o s i t i o n s at which L 1 V * This paper is based on work performed at Oak Ridge National Laboratory, which is operated by Union Carbide Corporation for the Atomic Energy Commission. ~ Previous paper in series: "hwest('~,ations on the System NiO--SO3-H20 and its DzO Analqg, ue/i'om 10 ~ to 2 m SOs, 150-400°C. '' W. L. MARSHAH.,J. S. Girl. and R. SIUSHER,J. hlorg. Nttcl. ('hem. In press 11962). '~' C H. SEcov, J. Amer. Chem. Soc, 72, 3343 (1950). ':' n. F. McDtIFVlE,Review in Fluid Fuel Reactors (Edited by J. A. LANE, H. G. MACPHEI~.St)N.[. ~'~ASLAN)pp. 85-127 Addison-Wesley Reading, Mass. (1958). '~' [!. V. JONESand W. L. MARSHALL,J. Ino~g. Nucl. Chem. 23, 287 (1961). ':~ l-:. E. CLARK.J. S. Gmc, R. SLUSHERand C. H. SECOY,J. Chem. Engp{~. Data, 4, 12 (1959). C. H. SECO¥, Report ORNL-607, pp. 33-38 11949). 995
996
W . L . MARSHALL,E. V. JONES,G. M. HEBERTand F. J. SMITH
super-critical fluid w o u l d be f o u n d i n d i c a t i n g a p p r e c i a b l e solubility o f UOa a n d C u O in supercritical fluids S O 3 - H 2 0 a n d S O 3 - D 2 0 . I n a d d i t i o n to being o f f u n d a m e n t a l interest, the phase b o u n d a r y i n f o r m a t i o n on the systems c o n t a i n i n g u r a n i u m w o u l d be useful in specifying o p e r a t i n g limits o f t e m p e r a t u r e a n d c o m p o s i t i o n f o r a q u e o u s h o m o g e n e o u s r e a c t o r fuels. I n f o r m a t i o n o n systems c o n t a i n i n g c o p p e r w o u l d be useful since c o p p e r has been included in fuel c o m p o s i t i o n s as a catalyst for the r e c o m b i n a t i o n o f radiolytic Ha a n d 02. (37 The o p e r a t i n g t e m p e r a t u r e s o f a q u e o u s h o m o g e n e o u s reactors m i g h t be extended a b o v e 370 ° b y using fuels o f c o m p o s i t i o n s showing critical p h e n o m e n a b u t no phase changes a t c o n s i d e r a b l y l o w e r temperatures. The v a p o u r phase c o u l d be eliminated at all temp e r a t u r e s b y m a i n t a i n i n g a h y d r o s t a t i c pressure on the system greater t h a n the critical pressure. This p a p e r presents some l i q u i d - l i q u i d immiscibility limits o f t e m p e r a t u r e a n d c o m p o s i t i o n as well as some t e m p e r a t u r e s for critical p h e n o m e n a in the systems UO3-SOz-H20, UO3-SO3-D20, and CuO-SOz-D~O. EXPERIMENTAL PROCEDURES The preparation of stock solutions of UO3 or of CuO dissolved in H~SO4--H20 or D2SO4--D20, and the chemical analyses for UO z, CuO and SOa were performed in the manner described previously.~4,7~ The source of the UOa'H20, H2SO4, and D20 reagents was the same as for the previous work although the D20 was found by an improved analysis to contain only 0-3 ~ H20 instead of 2 ~ reported previously. Experimental runs by the synthetic method were carried out in the type of apparatus described elsewhere~8) using quartz capillary tubes which contained solutions of known compositions. Supersaturation by the heavy liquid phase was not observed. The absence of supersaturation in experiments conducted previously(Z,5,8) indicated that no supersaturation was to be expected in these experiments. Appearance of immiscibility or critical phenomenon was instantaneous at temperatures defining the phase boundary limits. The tubes containing solutions were filled 40-50 per cent full at 25 ° and at final temperatures were from 50-90 per cent full. RESULTS AND DISCUSSION E x p e r i m e n t a l d a t a given in Tables 1, 2 a n d 3 are s h o w n g r a p h i c a l l y in Figs, 1, 2 a n d 3 for the systems U O 3 - S O a - H 2 0 , U O a - S O 3 - D z O , a n d C u O - S O z - D 2 0 , respectively. TABLE 1.--TEMPERATURES( ° C ) FOR THE APPEARANCE OF LIQUID-LIQUID IMMISCIBILITY AND CRITICAL PHENOMENA IN THE SYSTEM U O a - S O a - H a O ; Molal ratio mt, oJms%
0.2000
SO3 ( m o l a l i t y ) 0.1000 0.0500
1.000 0.950 0.900 0.800 0.750 0.700 0.600 0.500 0.400 0.300 0.250 0.2000 0.1000 0.0000
298.0L* 301.5L 306.8L 316-0L -325.0L 334.2L 344.6L 357'5L 370.0L -380C -380C
308.9L 312.2L 316.3L 324.8L -331.5L 340.0L 348.8L 358'3L 368.5L -377LC(?) -379C
321.0L + S -327.0L + S 333'6L -340.6L 348.2L 356.0L 363.0L 370.4L -378C 377C --
0.0200 < 350S -<350S -351.8L -357-8L 362.8L 368-4L 375LC(?) 374C ----
liquid-liquid immiscibility, C = critical phenomena, S = solid phase (presumably UO3 hydrate) (71 E. V. JONESand W. L. MARSHALL,J. Inorg. Nucl. Chem. 23, 295 (1961). ~8) C. J. BARTON,G. M. HEBERTand W. L. MARSHALL,Y. Inorg. Nucl. Chem. 21, 141 (1961).
* L =
997
Aqueous systems at high temperature--VII TABLE2.--TEMPERATURES(°C) EOR THE APPEARANCEOF LIQUID-LIQUID UOa-SOz-D20;
IMMISCIBILITY AND CRITICAL PHENOMENA IN THE SYSTEM
Molal ratio
SOa (molality)
I/1U03] 'IIISO 3
1.000 0.800 0.600 0.500 0.400 0-300 0.2000 0-1000 0-0000
1.000
0.800
0-600
0.364
0.2000
0.1000
0.0500
0.0200
277.5L* 306.3L 341.8L 360.5L 378.7L 396C (0-59)t 399C (0'61) 402C (0.61) 408C
277.8L 299.2L 332.7L 355.5L 375.8L 378C (0-62) 396C (0'52) 399C (0.51) 400C
278.5L 301-2L 331.0L . . 367.8L 383.6L . . 392C (0"50) 395C (0.43) 392C
28 I.OL 302.6L 328.2L . . 358.7L 375.2L . . . 383C (0'49) 383C (0-49) 384C
287.8L 306.8L 329.2L . 3593L -. . 380C (0"44) 377C (0.53) 379C
297.4L 315.5L 332.5L
313.0L 328.0L 343.3L 352.3L 362.5L 374C (0.48) 373C (0"48) 373C (0.52) 373C
31 IS 337.7L 352-0L 358-7L 365.0L 373(' (0.47) 373( (0-48) 374C (0.50) 372C
354-5L -375C --k_ 376C
* L - : liquid liquid immiscibility, C -- critical phenomena, S ~ solid phase (presumably UOa hydrate), ? Value in parentheses = density of supercritical fluid at temperature. ]'ABLE 3 . - - T E M P E R A T U R E S ( o f ) FOR THE APPEARANCE OF LIQUID-LIQUID IMMISCIBILITY AND CRITICAL PHENOMENA 1N THE SYSTEM C u O - S O a - D e O ;
Molal ratio mcu°Pns°a 1 "000
•800 -700 "600 -500 •400 •300 •2000 •1000
SO~ (molalit},)
1000 S*
326L 347/. 367/. 384L 408L 428L 422C 415C
0.800
0.600
0.364
0.2000
0.1000
0.0500
0.0200
S
S
S
S
S
S
S
325L 341L 363L 381L 400L 419L 411C 406C
S 350L 361L 373L 385L 397/. 393C 391C
S 336L 352L 367L 381L 389C 387C 385C
S 334L 354L 372L 381C 380C 379C 379C
S S 360L 378L 377C 376C 376C 376C
S S S 374C 374C 373C 373C 373C
S S S S 373(7 373C 373(" 372C
* L = liquid-liquid immiscibility, C -- critical phenomena, S 2CuO-CuSO4-2DeO)
blue green solid (presumably
T h e s y m b o l ( ! S) u s e d in T a b l e l indicates a small a m o u n t o f solid f o r m i n g at t e m p e r a t u r e s s o m e w h a t b e l o w those r e p o r t e d for l i q u i d - l i q u i d immiscibility. T h e c o m b i n e d s y m b o l s LC(?) designate a n a p p a r e n t l y s i m u l t a n e o u s a p p e a r a n c e o f s e c o n d liquid phase a n d critical p h e n o m e n o n . W h e r e o n l y the s y m b o l S is given b u t n o t e m p e r a t u r e is r e p o r t e d a solid phase a p p e a r e d at t e m p e r a t u r e s c o n s i d e r a b l y b e l o w those for l i q u i d - l i q u i d i m m i s c i b i l i t y or critical p h e n o m e n o n . Also i n c l u d e d in Fig. l are s o m e l i q u i d - l i q u i d i m m i s c i b i l i t y t e m p e r a t u r e s i n t e r p o l a t e d f r o m the d a t a o f CLARK et al. (a~ E a c h curve represents phase b o u n d a r y c o n d i t i o n s o f t e m p e r a t u r e a n d c o m p o s i t i o n expressed as m o l a l ratios R U a n d R c u for initial c o m p o s i t i o n s c o n t a i n i n g a fixed c o n c e n t r a t i o n o f SOa, specified for each curve. There are two phase b o u n d a r y regions s h o w n l b r each s y s t e m - - t h a t o f l i q u i d - l i q u i d i m m i s c i b i l i t y a n d t h a t o f critical p h e n o m e n o n . F o r a fixed c o n c e n t r a t i o n o f SOa the two curves r e p r e s e n t i n g these b o u n d a r i e s intersect at a n (isothermal) critical e n d p o i n t where the c o m p o s i t i o n o f the light-liquid phase (L 0 - - v a p o u r phase (V) supercritical fluid. T h e c o m p o s i t i o n s o f h e a v y liquid phases (L2) which first a p p e a r in the systems U O a - S O a - H , O a n d
W. L. MARSHALL,E. V. JONES,G. M. HEBERTand F. J. SMITH
998
I
41o
SUPERCRITICAL 400 __FLUIDREGION
I
ISTUCKEY,SEC0'I 390 - - f i I
I
/CRITICAL PHENOMENA
REGIONOF
_----~ _ _ _ _ =
IMMISCIBILITY
~
350
PRECIPITATION
L ^ ^e I ~ o
w 340
\
330
"% OF SOLID
~ PHASE
o., ~ . .
REG,0N OF
UNSATURATED SOLUTION
320
~
3,0
m.,.@ FROMDATAOFCLARK,e t o l
~
300 290
i
0
O',
0"2
0'3
0"4
0"5
0"6
0'7
0'8
0"9
1'0
muo3/ms03
MOLAL RATIO,
F1G. 1.--System UOa-SO~-H20, liquid-liquid immiscibility and critical phenomena. SUPERCRITICAL FLUID REGION
420
410
.f
CRITICAL PHENOMENA
400
~ 390 I ..... 380 ~
~
i,
"*",,,~
S03,m ~.I'0
k,.~. ~-~, ="~ ~-'%~ ~ i I. . . . .
~ _ _ _ _ --00""86
}---
),,=..., ~ . . . . . 370 ~
REGION OF LIQUID-LIQUID IMMISCIBILITY
-0"36 ~ 0.05 -0"2
~ . ~
360 !
g ~o
,~
340
~ X~
o.
~
~
330
PRECIPITATION
OFSOLID PHASE r"-.
-\
~
320
300
REGION OF 290
UNSATURATED
SOLUTION
280 270 0
0"1
0'2
0"3
0.4
O'S
0"6
0-7
0"8
0"9
t-0
MOLAL RATIO, muo 3 /mSO 3
FIG. 2.--System UO~-SOa-D~O, liquid-liquid immiscibility and critical phenomena.
999
Aqueous systems at high temperature--VII
i
I
L SUPERCRITICAL 450 I--FLUID REGION --
440
1
!
1
i
ITICAL
,
,
[
[
|PHENOMENAl
[
430
420
410
400
g FbJ (2. bJ F-
390 380 370 360 350 340 330 320 0
0-1
0"2
0o3
0-4
0"5
MOLAL RATIO,
0"6
0'7
0"8
0"9
90
mcuo/mso 3
FiG. 3.--System CuO-SOa-D~O, liquid-liquid immiscibility and critical phenomena. U Q - S Q - D z O as the temperature is raised can be estimated from the data previously reported on equilibrium compositions with light-liquid phases. (4) In Figs. 1-3 the molalities are the molalities of the solutions introduced into the tubes, these solutions being L 1. For the dashed curves, which report the temperatures of the critical phenomenon of L 1 and V, the molalities represent also the molalities of L and V at the reported, apparent critical temperature. However, the true critical temperature (where L -- V) can be determined only at a volume filling of L 1 of 50 per cent at temperature. The actual fillings at final temperatures in most instances were larger than 50 per cent. But upon comparing some densities of the supercritical fluids in Table 2 (obtained from the densities at 25 ° and the liq uid: total-volume ratios) with those of pure D20 near its critical temperature, (9) and considering the higher densities of the solutions, the reported temperatures are believed to approximate rather closely the true values. Fig. 1 shows, in addition, some interpolations from critical temperatures obtained by SECOY and STUCKEYfor solutions of HzSO4-H20 at RU == 0 and at a final liquid-volume filling of 50 per cent. (l°) For the curves representing the appearance of L,, the composition of L 1 at the (9, G. M. HEBERT, H. F. McDurr~E and C. H. SEcoY, J. Phys. Chem. 62, 431 (1958). ,1.) j. E. STUCK};Y. Ph.D. Dissertation, The University of Oklahoma Graduate College, N o r m a n , Oklahoma (1957).
I000
W.L. MARSHALL,E. V. JONES,G. M. HEBERTand F. J. SMITH
recorded temperature will vary somewhat from the initial composition with variation in the percentage of filling. It was shown previously, however, that in the system UOs-SOa-H20 the immiscibility temperature was little affected by moderate changes in this percentage of filling. ~s~ At high concentrations of SOs the addition of UO s lowers the critical temperature. This may arise from a higher degree of association of UO2SO ~ than of H2SO4; thus as UO a is added a decrease in concentration of ionic species lowers the critical temperature. As more UO3 is added R E increases sufficiently that upon raising the temperature of the system liquid-liquid immiscibility rather than a critical phenomenon (L = V) is observed. For the system CuO-SOs-D20 at constant molality of SO s the addition of CuO component invariably raises the critical temperature (Fig. 3). Therefore CuSO 4 at these temperatures may dissociate to a greater extent than D2SO 4 and thus raise the critical temperature. From Figs. 2 and 3 it is seen that UO a and CuO are soluble up to a concentration near 0.3 molal in a supercritical SOs-D20 fluid which is 1.0 molal in SO s. These observations and a similar one on the system NiO-SOs-H20 (but near 0.1 molal NiO in 1.0 molal SOs) m indicate that other metallic oxides may show high solubilities in the supercritical fluids SOa-HoO and SOs-D20. Acknowledgement The authors thank Professor J. E. RleCI,New York University, for his constructive review of the manuscript.