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H U D P H iEQUIL IBRIE L S E V I E R Fluid Phase Equilibria 104 (1995) 261 -275

Vapor liquid solid equilibria in the system N H 3 - C O 2 - H 2 0 from around310 to 470 K: New experimental data and modelingF. Kurz B. Rumpf and G MaurerLeh rs tuh l f i i r Techn i sche T herm odyna mik , Univevs i tf f t Ka i sers lau tern ,D - 6 7 6 5 3 K a i s e r sl a u t er n G e r m a n y )K e y w o r d s : e x p e r i m e n t s , d a t a , g a s s o lu b i li t y, w e a k e l e c tr o l y t es , a m m o n i a , c a r b o n d i o x i d e , w a -t e r , c o r r e l a t i o n

Received 12 January 1994; accepted in final form 29 Aug ust 1994ABSTRACT

As pa r t o f an on go ing p ro j ec t dea l i ng wi th expe r imenta l and theo re t i ca l work on the so lub i l i tyof weak e l ec t ro ly t e gases l ike am mo nia , ca rbon d iox ide , su l fu r d iox ide , hydro gen su lf ide o r hyd rogencyan ide i n aqueous phases , t he s imul t aneous so lub i li t y o f am mo nia and ca rb on d iox ide i n wa te r wasm e a s u r e d i n t h e t e m p e r a t u r e r a n g e f r o m 31 3 K t o 35 3 K a t t o t a l p r e ss u r e s u p t o a b o u t 0 . 7 M P a .Th e mod e l p ropo sed b y Edw ards e t a l. (1978) is used t o cor re l a te t he new as we l l a s li t e ra tu re da t a(G 6pp e r t an d M aure r (1988) , Mi il le r e t a l. (1988)) . Expe r im enta l and ca l cu l a t ed re su l ts a re r epor t eda n d c o m p a r e d .INTRODUCTION

T h e s o l u b i l i t y o f w e a k e l e c t r o l y t e g a s e s li k e a m m o n i a , c a r b o n d i o x i d e , s u l f u r d i o x i d e o rh y d r o g e n c y a n i d e i n a q u e o u s p h a s e s m u s t b e k n o w n f o r p r o c e s s d e s i g n i n m a n y t e c h n i c a l a p -p l i c a ti o n s . T y p i c a l e x a m p l e s a r e a p p l i c a ti o n s i n t h e c h e m i c a l a n d o i l r e l a t e d i n d u s t r i e s , t h ep r o d u c t i o n o f f e r ti l iz e r s o r a p p l ic a t i o n s i n t h e fi el d o f e n v i r o n m e n t a l p r o t e c t i o n . C o r r e l a t i n ga n d p r e d i c t i n g t h e s i m u l t a n e o u s s o l u b il it y o f a m m o n i a a n d s o u r g as e s i n a q u e o u s p h a s e s is a ne x t r e m e l y d i f fi c u lt t a s k , p a r t i a l l y c a u s e d b y c h e m i c a l r e a c ti o n s i n t h e l i q u id p h a s e b u t a l s o d u et o t h e p o s s i b l e f o r m a t i o n o f s o l id p h a s e s .

C o n t i n u i n g e a r li e r w o r k o n t h e s i m u l t a n e o u s s o l ub i li ty o f a m m o n i a a n d s o u r g a s e s i n a q u e o u sp h a s e s ( G S p p e r t a n d M a u r e r ( 1 9 8 8 ) , M f il le r e t al . ( 1 9 8 8 ) , B i e li n g e t a l. ( 1 9 8 9 ) ) , t h i s c o n t r i -b u t i o n r e p o r t s o n n e w e x p e r i m e n t a l r e su l ts f o r th e s i m u l t a n e o u s s o l u b il it y o f a m m o n i a a n dc a r b o n d i o x id e i n w a t e r i n t h e t e m p e r a t u r e r a n g e fr o m 31 3 to 3 53 K , a m m o n i a a n d c a r b o nd i o x i d e m o l a l i t i e s u p t o a b o u t 1 2 a n d 1 0 m o l / k g a n d t o t a l p r e s s u r e s u p t o a b o u t 0 . 7 M P a .F r o m t h e n e w d a t a a n d t h o s e p u b l i s h e d e a r li e r ( G S p p e r t a n d M a u r e r ( 1 9 8 8 ) , M f i ll e r e t a l.( 1 9 8 8 ) ), i n t e r a c t i o n p a r a m e t e r s f o r a m o d i f i c a t io n o f P i t z e r ' s m o d e l w e r e d e t e r m i n e d . T h e c o r -r e l a ti o n d e s c r i b e s t h e u n d e r l y i n g e x p e r i m e n t a l d a t a n e a r l y w i th i n t h e e x p e r i m e n t a l u n c e r t a in t y .

1Corr espondence to G. M aurer, Lehrstuhl fi ir Technisehe Thermodynam ik, Universit~t Kaiserslautern, D67653 Kaiserslautern, Germany0378-3812/95/ 09.50 1995 - Elsevier Science B.V. All rights reservedSSD10378-3812 (94) 02653-X

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262 F . K u r = e t a l. /F lu id P h a s e E q u i l ib ria 1 0 4 1 9 9 5 ) 2 6 1 -2 7 5E X P E R I M E N T L

The apparat us and procedure are basically the same used in a previous investigation G6ppertand Maurer 1988)), therefore only some essentials are repeated here.

A thermos tate d, evacuated cell is filled with a known amount of water. After adding aknown amount of ammonia, the cell is filled stepwise with carbon dioxide. After each addition,the mixture is equilibrated and thereafter temperature, pressure and the gas phase volumeare measured. Furthermore, a small amount of the gas phase is withdrawn from the cell andanalyzed by gas chromatography. From the results for the composition of the vapor phase,the volume of the vapor phase and the total amounts of each substance charged into the cell,the overall amounts of ammonia and carbon dioxide dissolved in the liquid + solid) phase arecalculated.

The temperature is measured by a calibrated resistance thermometer with a maximum un-certainty of -4- 0.1 K. The pressure is determined by a pressure transducer mounted on bottomof the cell with an uncer tai nty of -4- 0.5 kPa. The composition of the vapor phase was deter-mined by using a gas chromatograph with a column of Hayesep P and a thermal conductivitycell. Before and after each series of measurements, the gas chromatograph was calibrated.

S U B S T N C E S

Ammonia > 99.999 moles percent) and carbon dioxide > 99.995 moles percent) werepurchased from Messer-Griesheim, Ludwigshafen and used without fu rther purification. Waterwas deionized and further purified by vacuum distillation.

R E S U L T S

The experimental results for the solubility of ammonia and carbon dioxide in water at tem-peratures from 313 to 353 K are given in tables 1 to 3. Two overall molalities of ammoniafftNH3 ~ 6 and 12 mol/kg) were invest igated at tota l pressures up to about 0.7 MPa corre-

sponding to overall amounts of carbon dioxide up to about 10 mol/kg. For some of the solutionsinvestigated, the appearance of a solid phase of NH4HC03 was observed, therefore the numberof phases is also given in tables 1 to 3. But the numbers given in tables 1 to 3 for the molalityof ammonia and carbon dioxide were not corrected for the precipita ted salt. Tables 1 to 3 alsocontain the estimated maximum uncertainties of the total and partial pressures which werecalculated considering the propagation of all experimental uncertainties.In Fig. 1 the results for the total pressure at 333 K are plotted vs. the overall molality ofcarbon dioxide. Adding carbon dioxide to an ammoniacal solution at first results in a decreasein the total pressure as both ammonia and carbon dioxide are converted into ionic, nonvolatileform. After passing a minimum, a steep increase in the total pressure is observed. Increasingthe overall amount of ammonia shifts the minimum to higher overall amounts of carbon dioxide.For the 12 molal ammoniacal solution and a carbon dioxide molality of about 8 mol/kg, a slightchange of slope in the total pressure curve is observed, thus indicating the formation of a solid

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F. Ku rz e t a l. / F lu i d Ph a se Eq u i l i b ria 1 0 4 1 9 9 5 ) 2 6 1 -2 7 5 263T a b l e h E x p . r e s u l t s fo r t h e s o l u b i l i t y o f a m m o n i a a n d c a r b o n d i o x i d e i n w a t e r a t 3 1 3 K

K m o l / k g m o l /k g k P a k P a k P a313.12 6 .318 +0 .009 0 24 .9 +1 .0 0 31 .5 +0 .7 2313.16 6.320 4.0.009 0.722 +0 .00 3 21.0 4-1.1 0.1 4-0.1 27.4 4-0.7 2313 .16 6.32 4 4.0.009 1.542 4.0.006 15.1 4.1.1 0.3 4-0.2 2 2.3 4-0.7 2313 .15 6.32 8 4.0.0 09 2.353 4.0.006 9 .2 4-0.9 1.1 4-0.3 17.5 4-0.7 2313 .17 6.331 4-0 .009 3.156 4-0.006 4.6 4-0.7 5.2 4-0.7 16.5 4-0.6 2313 .15 6.33 3 4-0.009 3.954 4-0.007 1.6 4-0.4 25.4 4-1.9 33.5 4-1.3 2313 .16 6.33 3 4-0.009 4.646 4-0.009 0.5 4-0.4 92.3 4-4.0 9 9.6 4-3.2313 .15 6.33 3 4 -0.009 5.202 4-0.010 0.2 4-0.2 143.4 4-7.5 150.2 4-6.6 3313 .13 6.33 3 4-0.009 5.760 4-0.012 0.0 287.1 4-20.1 293 .7 4-19.3 3313.17 6.334 4-0.009 6.039 4-0.016 0.0 504.4 4-44.8 511.3 4-44.2 3313 .11 11.82 3 4-0.01 0 53.0 4-1.5 0 59.5 4-0.8 2313 .10 11.82 5 4-0.01 0 .965 4-0.003 47.4 4-1.7 0.1 4-0.1 52.7 4-0.8 2313 .10 11.82 8 4-0.01 2 .024 4-0.005 39.5 4-1.6 0.3 4-0.3 4 5.4 4-0.8 2313 .09 11.831 4 -0.01 3.080 4-0.005 31.7 4-1.6 0.4 4-0.4 3 7.3 4-0.8 2313 .10 11.83 4 4-0.01 4.224 4-0.006 22.6 4-1.5 0.9 4-0.4 28.8 4-0.7 2313 .09 11.83 8 4-0.01 5.379 4-0.006 12.6 4-1.3 3.5 4-0.7 21.4 4-0.7 2313 .12 11.841 4-0.01 6.526 4-0.007 4.9 4-0.9 15.8 4-1.5 2 5.6 4-0.8 2313.11 11.84 2 4-0.01 7.667 4-0.007 2 .7 4-0.8 29.1 4-1.9 36.8 4-1.0 3313 .12 11.84 2 4-0.01 8.764 4-0.008 1.6 4-0.7 41.0 4-2.4 48.0 4-1.3 3313 .11 11.84 3 4-0.01 9 .707 4-0.008 0.9 4-0.7 62.5 4-3.3 69.0 4-2.1 3

p h a s e o f N H , H C O 3 i n t h e c e ll . T h i s w a s a ls o c o n f i r m e d b y a n a l y z i n g t h e s o l id p h a s e w i t h d r a w nf r o m t h e c e l l a f t e r t h e c o m p l e t i o n o f a s er i es o f m e a s u r e m e n t s .

I n F i g s . 2 a n d 3 , t h e p a r t i a l p r e s s u r e s o f a m m o n i a a n d c a r b o n d i o x i d e a r e s h o w n f o r t h e s a m es e ri e s o f m e a s u r e m e n t s . W h e n f f t c o 2 / f f t N H 3 i s l e ss t h a n a b o u t 0 .5 , c a r b o n d i o x i d e i s d i s s o l v e dn e a r l y c o m p l e t e l y c h e m i c a l l y , t h e r e f o r e t h e p a r t i a l p r e s s u r e o f c a r b o n d i o x i d e is v e r y s m a l l . I nt h e r e g i o n w h e r e n e a r l y a l l a m m o n i a i s s p e n t b y c h e m i c a l r e a c t i o n s , a s t e e p i n c r e a s e i n P c o 2 iso b s e r v ed . T h e p a r t i a l p r e s s u r e o f a m m o n i a d e c re a s es w i t h i n c r ea s i n g o v e r al l a m o u n t o f ca r b o nd i o x i d e w h e r e a s t h e p a r t i a l p r e s s u r e o f w a t e r d o e s n o t c h a n g e s ig n i f ic a n t l y . T h e s a m e b e h a v i o u ri s o b s e r v e d a t t h e o t h e r t e m p e r a t u r e s i n v e s ti g a t e d . A t 3 13 K , t h e f o r m a t i o n o f s o l id N H 4 H C O 3w a s o b s e r v e d f o r b o t h s e r ie s o f m e a s u r e m e n t s , i . e. a 6 a n d 1 2 m o l a l a m m o n i a c a l s o l u t i o n , w h e -r e a s a t 3 5 3 K t h e f o r m a t i o n o f a s o li d p h a s e c o u l d n o t b e d e t e c t e d f r o m t h e t o t a l p r e s s u r e c u r v e .

M O E L IN G

F i g . 4 s h o w s a s c h e m e o f t h e m o d e l a p p l i e d t o c o r re l a t e t h e d a t a . T h e m o d e l i s a n e x t e n s i o na n d m o d i f i c a t i o n o f t h e t h e r m o d y n a m i c fr a m e w o r k d ev e l o p e d b y E d w a r d s e t a l. 1 9 78 ). D u et o c h e m i c a l r e a c t i o n s i n t h e l i q u i d p h a s e , a m m o n i a a n d c a r b o n d i o x i d e a re n o t o n l y p r e s e n ti n n e u t r a l , b u t a l s o i n i o n ic f o r m . T o c a l c u l a t e th e t r u e m o l a l i t i e s i n t h e l i q u i d p h a s e , t h e

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264 F. Kurz et al . / Fluid Phase Equilibria 104 1995) 261 -275Table 2: Exp. results for the solubility of amm oni a and car bon dioxide in water at 333 K

T ~nNtG Am NH 3 fgtC 2 ATT~CO2 P N H a ] A p N H a P c o2 [ A p c 0 2 p ] A pK mol/k g mol/kg kPa kPa kPa

333.22 6.027 +0.011 0 50.4 +1.6 0 68.3 +0.9333.17 6.030 +0.011 0.517 +0.003 45.4 +1.6 0.2 +0.2 62.3 +0.9333.14 6.036 +0.011 1.120 +0.003 37.3 +1.5 0.9 +0.3 55.0 +0.9333.12 6.042 +0.010 1.720 +0.003 28.0 +1.3 2.5 +0.3 48.3 +0.9333.14 6.048 +0.010 2.329 4-0.003 19.7 4-1.1 7.0 4-0.6 44.6 +0.8333.15 6.053 4-0.010 2.927 +0.003 1 2 . 3 +0.9 19.9 +1.4 49.8 4-1.0333.15 6.057 +0.010 3.526 4-0.003 6.8 4-0.7 55.1 4-3.3 80.1 4-2.4333.14 6.060 +0.010 4.161 4-0.003 3.2 4-0 .5 169 .9 4-7.8 190.8 4-6.5333.15 6.061 4-0.010 4.683 4-0.003 1.7 +0.5 410.5 4-18.5 429.6 4-17.2333.18 6.061 4-0.010 4.957 4-0.003 1.1 4-0. 4 648.0 4-32.2 667.0 4-30.9333.14 11.910 4-0.013 0 112.6 4-2.0 0 129.5 4-1.1333.10 11.918 +0.013 1 .081 4-0.003 98.2 4-2.0 0.3 4-0.2 114.9 4-1 .1333.10 11.926 +0.012 2.179 4-0.003 82.8 4-1.9 0.8 +0.2 98.7 4-1.1333.08 11.937 +0.012 3.321 4-0.003 63.8 4-1.8 2.2 4-0.3 81.9 +1.0333.14 11.947 +0.012 4.444 4-0.003 44.9 4-1.6 5.7 4-0.5 66.8 4-1.0333.11 11.957 4-0.012 5.565 4-0.003 27.0 4-1.3 18.2 +1.2 61.3 4-0.9333.15 11.964 4-0.011 6.645 +0.003 13 .9 4-0.9 65.6 4-3.1 95.0 4-2.1333.12 11.968 +0.011 7.705 4-0.003 6.5 4-0 .6 2 2 5 . 1 4-6.6 247.4 4-5.3333.14 11.969 4-0.011 8.066 4-0.003 5.7 4-0. 6 274.1 4-6.2 295.8 4-5.0333.14 11.970 4-0.011 8.814 4-0.003 4.2 4-0 .5 340.6 4 -8 .1 360.7 +6.8333.12 11.970 4-0.011 9.693 4-0.003 2.6 4-0.5 488.2 4-1 3.1 506.9 4-11.9

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conditi on for chemical eq uilibr ium for each reaction R is applied:g n T ) = H a 7 ,R (1)Whe n a solid phase of pure NH4HCOa is present, the following equati on for equilibr ium betweenthe solid and the liquid phase holds:KNH 4H C O 3 T) = aNH + . aH CO [ . (2)

The balance equations for the number of moles of ammonia, carbon dioxide and water yield:fiNHa = nlVHa + nlVH+ + nNH2CO0- + nNH, lCOa s)no02 = rico2 + nHCO~ -l- riCO~- + nNH2CO0- -l- nNH4HCOa s)n i l 2 0 = n i l 2 0 + n O H - + n H C O ~ + n c o ~ - + n N H , H C O a ,) Together with the charge balancen N H + + n i l + = n H C O ~ + 2 n c o ~ - + n N H 2 C O 0 - + n O H -

3 )4 )5 )

6 )

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F. Kurz et al . / Flu id Phase Equilibria 104 (1995) 261 -2 75 265

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F i g u r e I : T o t a l p r e s s u r e i n t h e s y s t e m N H s - C O 2 - H 2 0 t 3 3 3 K . o , C]: e x p . r e s u l t s , t h i s w o r k .: ca l c . resu l t s , t h i s w ork . - . . . . .. : ca lc . so lub i l i ty l imi t fo r the p rec ip i t a t io n NH4HCO 3

t h i s s e t o f e q u a t i o n s c a n b e s o lv e d i n a n i t e r a t i v e p r o c e d u r e t o y i e l d th e t r u e n u m b e r o f mo l e so f e a c h s p e c i e s p r e s e n t i n t h e l i q u id p h a s e a n d t h e n u m b e r o f mo l e s o f s o l id N H 4 H C O 3 . T h ec o n d i t i o n o f s o li d - li q u i d e q u i l i b r iu m i s o n l y t a k e n i n t o a c c o u n t w h e n i n a p r e l i m i n a r y c a l c u l a t i o n- w h e r e t h e f o r m a t i o n o f a s o l id p h a s e w a s n e g l e c t e d - t h e r i g h t h a n d s i d e o f eq . ( 2 ) p r o v e d t ob e l a r g e r t h a n t h e l e f t h a n d s i d e .

T h e t o t a l p r e s s u r e a n d t h e c o m p o s i t i o n o f t h e v a p o r p h a s e w e r e c a lc u l a t e d f r o mp . y ~ - ~ ' = p ~ . ~ " e x p ( v ~ " ( P - p ~ )-~-. y ) . aw (7)

m ) , . e x p V .p . y i . ~ = H ~ .,o ( T , p ~ , ) R '-~ T ) ' m i 7 i i = N S 3 , C O 2 . ( 8)T h e c a l c u l a ti o n r e q u i r e s t h e k n o w l e d g e o f t h e t e m p e r a t u r e d e p e n d e n t e q u i l ib r i u m c o n s t a n t sK ~- K s , t h e s o l u b i l i t y c o n s t a n t K N H , H C 0 3 , t he ac t iv i ty coef f i c ien t s o f a l l spec ies p resen t in thel iq u id p h a s e , H e n r y ' s c o n s t a n t s l - l ' ) f or a m m o n i a a n d c a r b o n d i o xi d e in p u r e w a t e r , t h e v a p o r- , ,~p r e s s u r e , m o l a r v o l u me a n d d i e l e c tr i c c o n s t a n t o f w a t e r as w e ll a s i n f o r ma t i o n o n t h e v a p o rp h a s e n o n i d e a l i t y a n d t h e p a r t i a l m o l a r v o l u me s o f t h e d i s s o lv e d g a s e s. T h e e q u i l i b r i u m c o n -s t a n t s K I t o K s w e r e ta k e n f r o m B i e li n g e t al . ( 19 89 ). H e n r y ' s c o n s t a n t s f o r a m m o n i a a n dc a r b o n d i o x i d e w e r e o b t a i n e d f r o m B i e l in g e t a l. ( 19 89 ) a n d R u m p f a n d M a u r e r ( 1 9 9 3a ) , r e -s p e c t i v e ly . T o a f i r s t a p p r o x i m a t i o n , t h e s o l u b il i ty c o n s t a n t K N H 4 n c o 3 w a s e s t i m a t e d f r o m t h en u m b e r s f o r t h e s t a n d a r d e n t r op i e s a n d e n t h a l p ie s o f f o r m a t i o n f o r N H + , H C O 3 a n d N H 4 H C O 3g i v e n b y W a g m a n e t a l . ( 19 8 2) . T h e d i el e ct ri c c o n s t a n t o f p u r e w a t e r w a s t a k e n f r o m B r a d l e ya n d P i t z e r ( 19 7 9) . T h e v a p o r p r e s su r e a n d t h e m o l a r v o l u m e o f w a t e r w e r e ta k e n f r o m S a u l

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266 F. Kurz et al. / Fluid P hase Equilibria 104 (1995) 261-275

7 O .

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4 6 8 1

F i gu re 2 : P a r t i a l p res s u re o f ca rbo n d i ox i de i n t he s y s t em NH 3-C O2-H 20 a t 333 K . o , 1 :3: exp .r e s u l t s , t h i s work . : ca l c . r e s u l t s, t h i s work . - . . . .. : ca l c . s o l ub i l it y l i m i t fo r t he p rec i p i t a t i onN H 4 H C O 3 .a n d W a g n e r ( 1 9 8 7 ). A t r u n c a t e d v i ri a l e q u a t i o n o f s t a t e w a s u s ed t o c a l c u l a t e t h e f u g a c i t ycoe f f ic i en t s. P u re com pon en t s eco nd v i r i a l coe f f ic i en ts B i, ; were ca l cu l a t ed f rom a co r r e l a t i onb a s e d o n d a t a r e c o m m e n d e d b y D y m o n d a n d S m i t h ( 19 8 0 ). M i x e d s ec o n d v i ri a l c o e f fi c ie n t sB i d w e r e ta k e n f r o m H a y d e n a n d O ' C o n n e l l (1 97 5) . T h e p a r t i a l m o l a r v o l u m e s o f th e d i ss o lv e dg a se s w e r e c a l c u l a t e d a s r e c o m m e n d e d b y B r e l v i a n d O ' C o n n e l l ( 1 9 72 ) .

T h e r e e x i s t f e w r e l ia b l e m e t h o d s t o c a l c u l a t e a c t i v i t y c o ef f ic i en t s o f b o t h n e u t r a l a n d i o n ics pec i es i n con cen t ra t ed e l ec t ro l y t e s o l u t ions . A we l l e s t ab l i s hed m e t ho d i s t he P i t ze r (1973 )e q u a t i o n f o r t h e e x c e s s G i b b s e n e r g y o f a n a q u e o u s e l e c t r o l y t e m i x t u r e :

). T . n w . M , o = f l ( I ) + E m i . m j . ~ ) + / ~ ~ ) . f 2 ( I ) + E m i . m j . m k . r i , j , k . (9)(id) ~ (id,k) ~,whe re f l and f2 a re fun c t i ons o f i on i c s tr eng t h I and / ~ 0 ) / ~ 9 ) and r l ,/ ,k a re b i n a ry a nd t e rn a ryl i J ' r 1 Ji n t e r a c t i o n p a r a m e t e r s . T h e r e s u l t i n g e x p r e ss i o ns f o r th e a c t i v i t y o f a d i s s o lv e d s p e c ie s a n d o fwa t e r a re g i ven e l s ewhere (R u m pf and M aure r , (1993a ,b ) ) . As 8 d is s o l ved s pec i es a re cons i de redt o b e p r e s e n t i n t h e l iq u i d p h a s e , t h a t e q u a t i o n i n p r i n c ip l e r e q u i re s 7 2 b i n a r y a n d 1 20 t e r n a r yp a r a m e t e r s . B u t t h i s p r o h i b i t i v e l y l a rg e n u m b e r o f u n k n o w n s c a n b e r e d u c e d b y t h e f o l lo w i n g~(0)a p p r o x i m a t i o n s : T h e b i n a r y p a r a m e t e r ~'N X3,N H3 W as o b t a i n e d f r o m t h e b i n a r y s u b s y s t e ma m m o n i a - w a t e r ( c f . R u m p f a n d M a u r e r ( 1 9 9 3 b) ) . A s t h e a m o u n t o f n e u t r a l c a r b o n d i o x i d e i n

g o )t h e l i q u i d p h a s e r e m a i n s s m a l l e v e n a t h i g h p r e ss u r e s, t h e b i n a r y p a r a m e t e r ~'co2,co2 was set

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F . K u r z e t a l , / F l u i d P h a s e E q u i l i b r i a 1 0 4 ( 1 9 9 5 ) 2 6 1 2 7 5 267i t z ~ --N /d l ~10 8

0.6

0 . 4 . 1 ~

0 . 2 . ~ -6 0 5

O 0 2 4 6 8 Ir Cm n/kgF i g u r e 3 : P a r t i a l p r e s s u r e o f a m m o n i a i n t h e s y s t e m N H 3 - C O 2 - H 2 0 a t 3 3 3 K : o , Q :r e s u l t s , t h i s w o r k . - -N H 4 H C O 3 .

e x p .: c a l c . r e s u l t s , t h i s w o r k . - . . .. . . : c a l c. s o l u b i l i t y l i m i t f o r t h e p r e c i p i t a t i o n

v a p o rN H 3 C 0 2 H 2 0

N H 3 C02 H20N H a + H 2 0 ~ N H + + O H - ( 1CO2+ n20 ~ HCO~+ H+ (2 ,

HCO~ = C O ~ - + H+ (3NH3 + HCO3 = NH2COO- + H20 (4 ,

H 2 0 = H+ + O H - ( 5

N H 4 H C O 3 s o l i d

F i g u r e 4 : V L E , S L E a n d c h e m i c a l re a c ti o n s in t h e a m m o n i a - c a r b o n d i o x i d e -w a t e r s y s t e mt o z er o . T h e c o n c e n t r a t i o n o f H + a n d O H - is r a t h e r s m a l l i n c o m p a r i s o n t o o t h e r s p e c i e s , t h u sa l l i n t e r a c t i o n p a r a m e t e r s b e t w e e n t h o s e a n d o t h e r s o l u t e s p e c ie s w e r e s e t t o z e r o . T h e i o n i cs t r e n g t h d e p e n d e n c e o f t h e s e c o n d v i r i a l co e f fi c ie n t i n e q . 9 is q u e s t i o n a b l e f o r i n t e r a c t i o n s

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268T a b l e 3 : E x p . r e s u l t s f o r t h e s o l u b i l i t y o f

F. Kurz e t al . / F luid Phase Equilibr ia 104 1995) 26 1-2 75a m m o n i a a n d c a r b o n d i o x i d e in w a t e r a t 3 5 3 K

T m N H 3 ] A ~ t N H 3 r= llC 02] AI TIC 0 2 P N H 3 ] A p N H s P C 0 2 [ A P e 0 2K m o l / k g m o l / k g k P a k P a

353.23 6.831 4-0.012 0 114.1 +3 .3 0353.23 6.838 4-0.011 0.609 +0.0 03 100.2 4-3.8 1.2 4-0.8353 .23 6.84 6 4-0.011 1.228 4-0.006 84.2 4-3.6 4.3 4-1.0353 .22 6.85 2 4-0.011 1.686 -t-0.006 72.4 4-3.5 8.8 4-1.2353 .22 6.85 8 4-0.011 2.140 4-0.006 60.5 4-3.2 16.7 4-1.6353.23 6.864 4-0.011 2.595 +0 .00 7 48.5 4-3.0 31.3 4-2.6353.23 6.870 4-0.010 3.043 4-0.008 37.4 4-2.8 58.7 4-4.3353.23 6.876 4-0.010 3.575 4-0.009 25.9 +2 .3 124.7 4-7.1353.23 6.881 +0 .01 0 4.116 4-0.012 16.7 4-1.9 271.5 4-12.8353.22 6.883 4-0.010 4.458 4-0.015 12.1 +1 .7 440.7 4-19.5353.23 6.884 4-0.010 4.698 4-0.008 9.9 4-1.6 61 9.6 4-27.5353.16 11.977 4-0.015 0 210.5 +3 .7 0353.18 11.986 4- 0.0 15 0.850 4-0.003 192.8 + 3.5 0.8 4-0.3353 .14 11.998 4-0.01 4 1.705 4-0.006 171.1 4-3.4 2.5 4-0.3353.13 12.011 4-0.014 2.579 +0.0 06 146.3 4-3.3 5.8 4-0.5353 .17 12.024 4-0.014 3.430 4-0.007 121.6 4-3.1 11.7 4-0.7353 .12 12.038 4-0.013 4.30 4 4-0.007 95.3 4-3.1 23.9 4-1.4353 .17 12.052 4-0.013 5.179 4-0.009 69.6 4-2.8 52.7 4-3.0353.11 12.063 4-0.013 6.003 4-0.010 47.7 4-2.3 117.0 4-5.8353 .12 12.073 4-0.01 2 6.847 4-0.013 30.3 4-1.7 277.1 4-11.1353 .18 12.077 4-0.012 7.348 4-0.016 22.8 4-1.3 46 5.9 4-17.1353 .19 12.078 4-0.012 7.602 4-0.018 20.0 4-1.1 6 00.6 4-21.6

P I A p lrk P a

154.8 4-1.2 2141.7 4-1.2 2129.5 4-1.2 2122.3 4-1.2 2118.5 4-1.1 2121.2 4-1.2 2137.3 4-1.8 2191.5 4-3.8 2329.1 4-8.8 2492.9 4-15.4 2670.2 4-23.4 2252.5 4-1.6 2232.6 4-1.6 2211.6 4-1.6 2190.2 4-1.5 2171.0 -t-1.5 2157.1 4-1.4 2160.7 4-1.6 2203.3 4-3.5 2345.5 4-8.4 2526.6 4-14.3 2658.9 4-18.8 2

b e t w e e n a n e u t r a l a n d a c h a r g e d c o m p o n e n t , t h e r e f o r e a ll p a r a m e t e r s fl~ ,~) f o r i n t e r a c t i o n sb e t w e e n a n e u t r a l a n d a c h a r g e d c o m p o n e n t w e r e s e t to z er o .

T o f u r t h e r r e d u c e t h e n u m b e r o f p a r a m e t e r s , a l l p a r a m e t e r s f o r i n t e r a c t io n s b e t w e e n t w o o rm o r e s p e c i e s w i t h t h e s a m e s i g n o f c h a r g e w er e n eg l e c te d . A m m o n i a a n d c a r b o n d i o x i d e a r e ra -

o ) rr e l y s i m u l t a n e o u s l y p r e s e n t i n s ig n i f i c an t a m o u n t s , t h e r e f o re , p a r a m e t e r s ~NHa,C02 NHa,NHa,C02a n d rNH3,Co2,co2 w e r e s et t o z e ro . I t f u r t h e r m o r e s e e m s t o b e r e a s o n a b l e t o n e g l e c t a l l t e r n a r yp a r a m e t e r s i n v o l v in g o n e n e u t r a l a n d t w o i on i c s p e ci e s w i t h t h e s a m e s i g n o f c h a r g e. W i t ht h e s e a s s u m p t i o n s , t h e r e m a i n i n g n u m b e r o f p a r a m e t e r s is 3 7 1 4 b i n a r y a n d 2 3 te r n a r y ) . T h eb i n a r y p a r a m e t e r s g 0 ) ;q o ) g 0 ) ~ 0 )/ . . i ,NH+, r. i,HCO~ t.,i,CO _ a n d ~ i ,NH ICO0- i = N H a o r C O 2 ) d e s c r i b e t h e e f-f e ct o f t h e d i s s o l v e d i o n s on t h e s o l u b i l i ty o f a m m o n i a a n d c a r b o n d i o x i d e . T h e d e t e r m i n a t i o no f t h e b i n a r y p a r a m e t e r s f o r in t e r a c t io n s b e t w e e n a m m o n i a a n d t h e d i s s o l v e d i o n s w as d o n ea s f o ll o w s: W i t h t h e a b o v e a s s u m p t i o n s a n d c o n s i d er i n g o n l y b i n a r y p a r a m e t e r s , t h e a c t i v i t yc o e f fi c i en t o f a m m o n i a i s:

~ o ) . R o )l 7 ; q H 3 ---- 2 ( r a N . 3 ~ ] ~ ) H 3 ,N H 31 - T r t N t N H , N + + [ n H C O ~ r - N H 3 , . C O ~

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F. Kurz et a l . / Flu id Phase Equi l ibria 104 (1995) 261-275 269~ o) :~ o)

~ - m c o ~ - ~ H ~ , C O ~ - - ~ m N H ~ C O 0 - ~ ' N H ~ , N H ~ C O 0 - :

N e g l e c t i n g t h e c o n c e n t r a t i o n s o f H + a n d O H - , t h e c h a r g e b a l a n c e y i e ld s10)

m N lf 4+ ~ m H C O 7 + 2 . m o o ~ - + m N m c O O - 11)F rom eq . 10 ) i t fo l lows

:fifo) /~ o)= 2 . . + m .o o , N . 3 , N . : ++ m c o ~ - . r ~ N n 3 , C O ~ - J

: :~(o) :~(o)- ~ m N H 2 c O 0 - ~ N H 3 , N H + - ~ ~ ' N m , N H ~ C O 0 - ) 1 2 )W i t h th e d e f in i t io n c f . R u m p f a n d M a u r e r 1 9 9 3 a) )B ) = u+ :~ o) /3 o) 13 )G , M X I J G , M + I / _ G , Xt h a t e q u a t i o n y i e l d sl r t T N H 3 - - 2 ( m N H 3 1.4(0) . B ( o )- - ~ ' N H 3 , N H 3 - ~ m H C O [ N H 3 , N H 4 H C 0 3

/ : ~ ( 0 ) N H 3 , N H 2 C O O N I f 4 /~ - m c o ] - ~ N H 3 ,( N H 4 )2 C 0 3 ~ m N H ~ c O 0 - B ( 0 ) % 14)wh i ch i s a s i m i l a r equ a t i on we f ind fo r t he s o l ub i l i t y o f a no n reac t i ng gas in an aqueou s m i x t u rec o n t a i n i n g s t r o n g e l e c t ro l y t e s f o r d e t a i ls s e e R u m p f a n d M a u r e r 1 9 9 3 a )) . F o r t h e p r e s e n t:~ o)c a s e , w e c a n t h e r e f o r e a r b i t r a r i l y s e t ~ N n 3 , N H + to zero . Pa ram ete rs :~ o) ~ o)r H 3 , 1 I C O [ ' ~ ' N I I 3 , C O ~ - a n d~ ( N ) s , N H 2 C O 0 _ w e r e t h e n d e t e r m i n e d f r o m f it s t o t h e n e w e x p e r i m e n t a l r e s u lt s f o r t h e p a r t i a lp r e s s u r e o f a m m o n i a a s w e ll a s t o th e r e s u lt s re p o r t e d b y G S p p e r t a n d M a u r e r 1 9 8 8) a n dM f i ll e r e t a l . 1 9 8 8) . T h e t e m p e r a t u r e d e p e n d e n c e o f t h e b i n a r y p a r a m e t e r s w a s a p p r o x i m a t e db y~N(O ) b N H3,____.~ ( 1 5 )H 3 , 1 = a N H 3 , i ~ - ( T / K )P a r a m e t e r s a NH3 , i a n d b N H 3 , i w e r e t h e n s i m u l t a n e o u s l y d e t e r m i n e d i n t h e t e m p e r a t u r e r a n g ef rom 313 .15 t o 473 .15 K f rom f i ts t o t he pa r t i a l p res s u re o f am m on i a . Th e r e s u l t s a re g i-v e n in t a b l e 4 . A t t e m p t s t o i n c l u d e t e r n a r y p a r a m e t e r s d i d n o t y i e ld a s i g n if i ca n t im p r o v e -m e n t , t h e r e f o r e al l t e r n a r y p a r a m e t e r s f o r i n t e ra c t i o n s b e tw e e n a m m o n i a a n d N H 4 + , H C O ~o r C O ~ - w e r e f in a l ly se t t o z e r o . I n t h e n e x t s t e p , p a r a m e t e r s d e s c r ib i n g i n t e r a c t i o n s b e t -w e e n c a r b o n d i o x i d e a n d t h e d i s s ol v e d i on s w e r e d e t e r m i n e d . F o ll o w in g t h e a r g u m e n t g i v e nabove , t he re a re t h re e r em a i n i ng b i na ry pa ra m e t e r s { ~ o ) ~ o ) R o )x C O a , H C O ~ I ~ ' C O ~ , C O ~ - ' ~ ' C O ~ , N H 2 C O 0 - /a n d s e v e n t e r n a r y p a r a m e t e r s C O 2 , G O 2 , N H ~ , T C O ~ , C O , , H C O [ , T C 0 2 , C O , , C O ~ _ , T C O 2 , C O 2 , N H a C O 0 _ ,r C O 2 , N H , , c o l ' T C O 2 , N H , , c o ] - ' T C O ~ , N ~ +, N H ~ C O 0 - ) P a r a m e t e r s d e s c r i b i n g i n t e r a c t i o n s b e t -w e e n t w o c a r b o n d i o x i d e m o l e cu l e s a n d a c h a r g e d s p e ci e s w e re n e g l e c t e d a s t h e m o l a l i t y o fc a r b o n d i o x i d e r e m a i n s s m a l l. T h e r e m a i n i n g p a r a m e t e r s w e r e th e n f i t t e d t o t h e e x p e r i m e n t a lr e s u l t s fo r t he pa r t i a l p res s u re o f ca rbo n d i ox i de . Du r i ng t h i s st ep , a l l S LV -da t a were exc l u ded

H ) and rcoa,NH+HCO w r f o u n d t o b er o m t h e d a t a b a s e . F i n a l ly , o n l y p a r a m e t e r s c o a , ~ c o [~ o) ~ 0)s ig n i fi c a nt . F u r t h e r m o r e , i n t e r a c t i o n p a r a m e t e r s ~ , H + , H C O [ , e , H + , C O ~ _ , T N H + , N H + , H C O ~ a n d

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270 F. Kurz e t a l . / F luid Phase Equi libria 104 (1995) 26 1-27 5T a b l e 4 : I n t e r a c t i o n p a r a m e t e r s t o d e s c r ib e V L E a n d S L E in t h e a m m o n i a - c a r b o n d i o x id e - w a t e rs y s t e m ( 3 1 3 . 1 5 < T / K < 4 7 3 . 1 5 )

Pa r a me t e r a ~ , j0.2857

N H 3 C O ~ -~ ~ ) H 3 , N H 2 C O 0 -8 C 0 2 , H C O ~fl(o)N I t : . c o ~

-0.3391-0.03933

0.08430.1134

b i j-99.466151.2825.263

-16.148-45.679

P a r a m e t e r-0 .146(oN . t c o ~ -

r C O = , N . , , H C O ~ -1 .1264.10 -3TNH4+,NH4+,HCO~ 5.0715 10 -4T ~-H ~ , N H ~ , C O 1 4 0 0 7 1 0 - 2

rNtI,+,NH+,,CO~- were inc luded in the f ina l f i ts . Th e resu l t s a re g iven in t ab le 4 . Us ing tha ts e t o f p a r a m e t e r s , a c o m p a r i s o n b e t w e e n c a l c u la t e d a n d e x p e r i m e n t a l r e s u lt s s h o w e d a g o o da g r e e m e n t f o r al l V L E d a t a p o i n ts . H o w e v e r , s y s t e m a t i c d e v ia t i on s b e t w e e n e x p e r i m e n t a l a n dc a l c u l a t e d t o t a l a n d p a r t i a l p r e s s u r e s a b o v e s o l u ti o n s w h e r e a so l id p h a s e w a s p r e s e n t w e r eo b s e r v e d , t h e d e v i a t i o n s i n c r e a s i n g w i t h t e mp e r a t u r e . A s n o r e l i a b l e i n f o r ma t i o n o n t h e t e m-p e r a t u r e d e p e n d e n c e o f KNH~HC03 w a s a v a il a b l e , t h e s e d e v i a t io n s w e r e e x p e c t e d . T h e r e f o r e ,n u m b e r s f o r t h e s o l u b i l it y c o n s t a n t a t 3 13 a n d 3 3 3 K w e r e d e t e r m i n e d f r o m t h e n e w d a t a w h e -r e a s t h e v a l u e a t 2 98 .1 5 K a s t a k e n f r o m W a g m a n e t a l . ( 1 98 2) w a s r e t a i n e d . T h e t e m p e r a t u r ed e p e n d e n c e o f t h e s o l u b il it y c o n s t a n t w a s a p p r o x i m a t e d b y

2465.32i n KNH HC03 8.3413 ( T / K ) (16)I n t a b l e 5 , t h e r e s u l t s f o r t h e a v e r a g e d e v i a t io n s i n t h e t o t a l p r e s s u r e a n d t h e p a r t i a l p r e s s u r e so f a m m o n i a a n d c a r b o n d i o x id e a re s u m m a r i z e d . T h e m o d e l gi ve s a g o o d r e p r e s e n t a t io n i nb o t h t h e t o t a l a n d t h e p a r t i a l p r e s s u re s u p t o e x t r e m e l y c o n c e n tr a t e d s o l ut io n s . T h e r e l a ti v ed e v i a t i o n s i n t h e t o t a l p r e s s u r e s i n mo s t c a s e s a mo u n t t o a f e w p e r c e n t , t h e l a r g e s t d e v i a t i o n sb e e i n g o b s e r v e d w h e n t h e t o t a l p r e s s u r e i n c r e a s e s r a p i d l y w i t h i n c r e a s i n g c a r b o n d i o x i d e mo l a -l it y . Fo r t h e p a r t i a l p r e s s u r e s o f a m m o n i a a n d w a t e r , s o me w h a t l a r g e r d e v i a t i o n s a r e o b s e r v e d .E s p e c i a l l y fo r t h e d a t a r e p o r t e d b y Mf i l le r e t a l . ( 1 98 8 ), s y s t e m a t i c d e v i a t i o n s i n t h e p a r t i a lp r e s s u re o f a m m o n i a a r e o b t a in e d . H o w e v e r, i t sh o u ld b e n o t e d t h a t d u e t o t h e e x p e r i m e n t a ld i ff ic u lt ie s a t t h e s e h i g h t e m p e r a t u r e s t h e s e d a t a a r e m o r e u n c e r ta i n . N o t e t h a t s o m e o f t h ed a t a r e p o r t e d b y G 6 p p e r t a n d M a u r e r ( 1 98 8 ) a s V L E - d a t a a r e n o w f o u n d t o b e S L V - d a t a .I n F i g s. 5 a n d 6 , t h e n e w r e s u l t s f o r t h e t o t a l p r e s s u r e a n d t h e p a r t i a l p r e s s u r e o f a m m o n i aa t 3 1 3 K a r e c o m p a r e d t o c a l c u l a t e d r e s u lt s . Fu r t h e r m o r e , t h e c a l c u l a t e d s o l u b i l it y li m i t fo r t h ep r e c i p i t a t i o n o f N H 4 H CO a is s h o w n . I n F ig . 7 , s o me t o t a l p r e s s u r e s a t 3 73 .1 5 K a s r e p o r t e db y Mf i ll e r e t a l . ( 1 9 88 ) a r e c o m p a r e d to c a l c u l a t e d r e s u lt s . T h e m o d e l c o r r e l a t e s t h e s e d a t aw i t h a n a v e r a g e r e l a t i v e d e v i a t i o n i n t h e t o t a l p r e s s u r e o f 3 . 6 % , t h e a v e r a g e r e l a t i v e d e v i a t i o ni n t h e p a r t i a l p r e s s u r e o f a mmo n i a i s 4 . 9 % .

I n F i g . 8 , e x p e r i m e n t a l d a t a f o r th e s o l u b i li t y l i m i t o f N H 4 H CO 3 in t h e N H 3 - CO 2 - H 2 0 -s y s t e m a s t a k e n f r o m J h n e c k e ( 19 29 ) a r e c o m p a r e d t o mo d e l c a l c u l a ti o n s . A g o o d a g r e e me n t

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F . K u r z e t a l. / F lu id P h a s e E q u i l ib ria 1 0 4 1 9 9 5 ) 2 6 1 -2 7 5 271T a b l e 5: C o m p a r i s o n b e t w e e n c a l c u l a te d a n d e x p e r i m e n t a l r e su l ts d a t a p o i n ts w i t h p _< 50 k P aa n d P l < 5 0 k P a o m i t t e d )

S o u r c e

T h i sw o r k

G 6 p p e r ta n dM a n r e r1988)

Mfi l lere t a l .1988)

TK

313.15333.15353.15333.15353.15360.15373.15393.15373.15393.15413.15433.15453.15473.15

mNH3 rnaz mco~ mazm o l / k g m o l / k g

11.8 9.712.0 9.712.1 7.611.8 12.212.2 11.416.0 13.514.3 10.412.0 7.426.0 13.325.9 12.725.2 8.524.6 9.812.6 3.810.6 2.1

N o . o f d a t a p o i n t s A v . d e v i a t i o n

P PNH3 PC 2 Pw P PNH3 PC 2 P~7 1 5 21 2 29

18 5 9 - 3.2 2 4.722 12 10 - 2.7 2.2 6.185 - 85 7.0 8.393 1 91 3.2 10 3.5183 35 156 140 5.6 8.1 6.9 11127 48 99 127 5.5 13 8.1 1574 33 63 74 4.4 20 11 2261 48 32 61 3.6 4.9 8.8 4.642 35 34 42 4.4 10 6.3 5.872 55 69 72 4.7 13 6.3 1240 36 40 40 4.9 12 5.9 1823 22 23 23 4.3 14 8.5 8.716 16 16 16 12 23 16 2.2

b e t w e e n e x p e r i m e n t a l a n d c a l c u l a t e d r e s u l t s i s o b s e r v e d . H o w e v e r , o n l y f e w d a t a l i m i t e d t o as m a l l r a n g e 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 a re a v a i la b le .

ON LUSIONS

T h e t o t a l a n d p a r t i a l p r e s s u re s a b o v e aq u e o us s o lu t io n s c o n ta i n in g a m m o n i a a n d c a r b o nd i o x i d e w e r e m e a s u r e d i n t h e t e m p e r a t u r e r a n g e f r o m 31 3 to 3 5 3 K a t o v e r a l l mo l a l i t i e s o fa m m o n i a o f a b o u t 6 a n d 1 2 m o l / k g a n d c a r b o n d i o x id e m o la l it ie s u p t o a b o u t 1 0 m o l / k g .F r o m t h e s e d a t a a n d t h o s e r e p o r t e d e a r l i e r G S p p e r t a n d M a n r e r 1 9 8 8 ), Mf il le r e t a l . 1 9 8 8 ) )i n t e r a c ti o n p a r a m e t e r s f o r a n a d a p t e d P i t z e r m o d e l w e r e d e t e r m i n e d . T h e m o d e l i s c a p a b l e t od e s c r i b e r e l i a b l y v a p o r - l i q u i d a n d v a p o r - l iq u i d - s o li d e q u il i b r ia i n t h i s e x t r e m e l y c o m p l e x s y s t e mi n t h e t e m p e r a t u r e r a n g e f r o m 31 3 t o 4 73 K u p t o c o n c e n t r a t e d s o l u ti o n s .

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272 F . K u r z e t al . / F l u i d P h a s e E q u i li b r ia 1 0 4 ( 19 9 5 ) 2 6 1 - 2 7 58

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F i g u r e 5 : T o t a l p r e s s u r e i n t h e s y s t e m N H a - C O 2 - H 2 0 a t 3 1 3 K . o n : e x p . r e s u l ts t h i s w o r k .- - : c .a lc r e s u l t s t h i s w o r k . - . . . .. . : t a l c . s o l u b i l i t y l i m i t f o r t h e p r e c i p i tt L t io n N H 4 H C O 3 .

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F i g u r e 6 : P a r t i a l p r e s s u r e o f a m m o n i a i n t h e s y s t e m N H 3 - C O ~ - H 2 0 a t 31 3 K . o D : e x p .r e s u l t s t h i s w o r k . : c a l c . r e s u l t s t h i s w o r k . - . . . .. . : c a l c . s o l u b i l i t y l i m i t f o r t h e p r e c i p i t a t i o nN H 4 H C O a .

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F . K u r z e t a l. / F lu id P h a s e E q u i l ib r ia 1 0 4 1 9 9 5 ) 2 6 1 -2 7 5 273I ] ,

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Fi g u r e 7 : T o t a l p r e s s u r e i n t h e s y s t e m N t t 3 - CO 2 - H 2 0 a t 3 7 3 K . o: e x p . r e s u l t s , Mf i ll e r e t a l .1 9 8 8 ). - - : c a l c . r e s u l t s , t h i s w o r k .

12.

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F i g u r e 8: S o l u b i li t y l i m i t s f o r t h e p r e c i p i t a ti o n o f N H 4 H C O s in t h e N H r C O 2 - H 2 0 - s y s t e m . O :exp . res ul ts at 293.15 K, JS~necke 1929). [::1 : exp . re sul ts at 313.15 K, J~n eck e 1929). - - :ca lc . resu l t s , t h i s work .

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2 7 4 F . K u r z e t a l. / F lu id P h a s e E q u i l ib ria 1 0 4 1 9 9 5 ) 2 6 1 -2 7 5

CKNOWLEDGEMENT

F inanc ia l s upp or t o f th i s inves t iga t ion by the governmen t o f the F edera l Repub l i c o f G erm any(BM F T G ra n t N o . 0326558 C) , BA S F A G , Ludw igs hafen , Bayer A G , Leverkus en , D egus s a A G ,H anau , H oechs t A G , F rank fu r t , L inde K CA , D res den and Lurg i A G , F rank fu r t i s g r a t e fu l lyacknow ledged .LIST OF SYMBOLSa~a~,j,bldB (o)G , M XB~ ~fi, f2G EH . ~ )IK RK N H 4 H G 0 3M ~r=t.tirrtml

n iPP iA pAp~RT

YG reek l e t t e r s~(o),/~0)~o7*~ i,Rv+,u_

a c t i v i t y o f c o m p o n e n t icoe f fi c ien t s fo r the t em pera tu re dep endence o f in t e r ac t ion pa ra me te r s

obs e rvab le com bina t ion o f b ina ry in te r ac t ion pa ram ete r ssecond v ir ia l coef fic ient for in teract ions b etween species i and jfunc t ions in P i t ze r ' s equa t ionexces s G ibbs ene rgyH e nry ' s con s tan t f o r the s o lub i l i ty o f gas i i n w a te r (on m o la l i ty s ca le )ion ic s t r eng th on m o la l i ty sca leequ i l ib r ium c ons tan t f o r chemica l reac t ion R (on mo la l i ty s ca le )s o lub i l i ty cons tan t f o r the fo rm at ion o f N H 4H CO 3 (on m o la l i ty s ca le )m o l a r m a s s o f w a t e r ( k g / m o l )overa l l mo la l i ty o f componen t it r u e m o l a l i t y o f c o m p o n e n t ie s t i m a t e d m a x i m u m a b s o lu t e u n c e r t a i n t y i n t h e o v e ra ll m o l a l i t y o f c o m p o n e n t iove ra l l numbe r o f mo les o f com ponen t it r ue num ber o f mo les o f com ponen t ito t a l p r es s u repa r t i a l p r es s u re o f componen t ie s t i m a t e d m a x i m u m a b s o l ut e u n c e r t a i n t y i n t h e t o t a l p r e s s u ree s t i m a t e d m a x i m u m a b s o l ut e u n c e r t a i n t y in t h e p a r t i a l p r e s su r e o f c o m p o n e n t iun ive r s a l gas cons tan tt e m p e r a t u r ep a r t i a l m o l a r v o l u m emole f r ac t ion in vapo rb ina ry in te r ac t ion pa ramete r s in P i t ze r ' s equa t ionfugaci ty coeff ic ientac t iv i ty coe f fi c ien t no rmal i zed to in f in it e d i lu t ion (on mo la l i ty s cale )s to ichiometr ic coef f ic ient of component i in react ion Rnumber o f ca t ions and an ions in s a l t M Xn u m b e r o f p h a s e st e r n a r y i n t e r a c ti o n p a r a m e t e r i n P i t z e r' s e q u a t i o n

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F . K u r z e t a l. / F l u i d P h a s e E q u i l i b r i a 1 0 4 1 9 9 5 ) 2 6 1 - 2 7 5 275S u b s c r i p t s S u p e r s c r i p t sG g a s G s s a t u r a t i o ni , j , k c o m p o n e n t i , j , k n o r m a l i z e d t o i n f in i t e d i l u t i o nM X s a l t M X c i n f in i te d i l u t i o nm a x m a x i m u m t s o li d p h a s eR r e a c t i o n R t t l i q u i d p h a s ew w a t e r t t t g a s p h a s eR E F E R E N E SB i e l i n g , V . , R u m p f , B . , S t r e p p , F . a n d M a u r e r , G . , 1 98 9. A n e v o lu t io n a ry o p t im i z a ti o n m e-

tho d fo r m o de l ing t he so lub i l i ty o f am m o nia and ca rbo n d iox ide i n aqueous so lu t i ons . F lu idPhase Equi l ibr ia , 53: 251-259.

B r a d l e y , D . J . a n d P i t z e r , K . S . , 1 97 9 . T h e r m o d y n a m i c s o f e l ec t ro l y te s . 1 2 . D i e le c t ri c p r o p e r -t i es o f wa te r an d Debye -Hi i cke l pa ram e te r s t o 350C and I kba r . J . Phys . Che m . , 83 : 1599-1603 .

B r e l v i , S . W . a n d O C o n n e l l , J . P . , 1 9 72 . C o r r e s p o n d i n g s t a t e s c o r r el a ti o n s f o r l iq u i d c o m p r e s si -bi l i ty and p ar t ia l mo la l volum es of gases a t inf ini te di lut ion in l iquids. A IC hE J . , 18: 1239-1243.

D y m o n d , J . H . a n d S m i t h , E . B . , 1 9 80 . T h e v ir ia l c oe ff ic ie nt s o f p u r e g a s e s a n d m i x t u r e s. O x -fo rd Unive r s i t y Pre ss , Oxfo rd .

E d w a r d s , T . J . , M a u r e r , G . , N e w m a n , J . a n d P r a u s n i t z , J . M . , 1 97 8. V a p or -l iq u id eq uili-b r i a i n m u l t i com pon en t aq ueous so lu t i ons o f vo l a ti l e weak e lec t ro ly te s . A IC hE J . , 24 : 966-976 .

G 6 p p e r t , U . a n d M a u r e r , G . , 1 98 8. V a p or -l iq u id e q ui li b ri a i n a q u eo u s s o lu t io n s o f a m m o n i a a n dc a r b o n d i o x id e a t t e m p e r a t u r e s b e tw e e n 3 3 3 a n d 3 93 K a n d p r e s s u re s u p t o 7 M P a ; F l u i d P h a s eEqui l ibr ia , 41: 153-185.

H a y d e n , J . G . a n d O C o n n e l l , J . P . , 1 97 5. A g en e ra li ze d m e t h o d f o r p r e d ic t in g s e c o n d vi ri alcoeff ic ients . Ind . Eng . Ch em . Pr oc . D es. Dev . , 14: 209-216.

J i l ne ck e , E . 1929. Z . E l ek t rochem . , 35 : 716-727 .M i i l l e r , G . , B e n d e r , E . a n d M a u r e r , G . , 1 9 88 . D a s D a m p f - F li is s ig k e it s g le i ch g e w i ch t d e s t e r n r e n

S y s t e m s A m m o n i a k - K o h l e n d i o x i d - W a s s e r b e i h o h e n W a s s e r g e h a l t e n i m B e r e i c h z w i s c h e n 3 7 3und 473 Ke lv in ; Be r . Bunsenges . Phys . Chem . , 92 : 148-160 .

P i t z e r , K . S . , 1 9 73 . T h e r m o d y n a m i c s o f e l ec t ro l y te s . 1 . T h e o r e t ic a l ba s is a n d g e n e ra l e q u a t i o n s .J . Phys . Chem . , 77 : 268-277 .

R u m p f , B . a n d M a u r e r , G . , 1 9 93 a. A n e x p e r im e n t a l a n d t h e o r e ti c a l i n v e s ti g a t io n o n t h e so l ub i -l i t y o f c a rb on d iox ide i n aqueous so lu ti ons o f s t rong e lec t ro ly t e s . Be r . Bunseng es . Phy s . Chem . ,97: 85-97.R u m p f , B . a n d M a u r e r , G . , 1 99 3b . S o l ub il it y o f a m m o n i a i n a q u eo u s s o lu t io n s o f s o d i um s u l fa t ea n d a m m o n i u m s u l f a te a t t e m p e r a t u r e s f r o m 33 3 .1 5 K t o 4 33 .1 5 K a n d p r e s s u re s u p t o 3 M P a ,Ind . E ng . Chem . Res . 32 : 1780-1789 .

S a u l , A . a n d W a g n e r , W . , 1 98 7. I n te r n a ti o n a l e q u a ti o n s f o r t h e sa t u r a ti o n p r op e r ti e s o f o r d i n a rywa te r subs t ance . J . Phys . Chem . Re f . Da t a , 16 : 893-901 .

W a g m a n , D . D . E v a n s W . H . P a r k e r V . B . S c h u m m R . H . . H a l o w I . B a i l e y S . M .Chu rney , K. L . and Nuta l l , R . L ., 1982. T h e NBS t ab l e s o f chem ica l t he r m o dy nam ic p rope r t i e s ,J . Phys . Chem . Re f . Da t a , Vo l . 11 .