IUPAC-NIST Solubilities Database

IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Solubility System: Carbon dioxide with Synthetic Salton Sea geothermal brine (SSGB) and Water

Components:
   (1) Synthetic Salton Sea geothermal brine (SSGB); ; []  NIST Chemistry WebBook for detail
   (2) Carbon dioxide; CO2; [124-38-9]  NIST Chemistry WebBook for detail
   (3) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail

Original Measurements:
   Cramer, S. D., Rep. Invest. - U.S., Bur, Mines 1982, RI 8706.

Variables:
   Temperature = 278.05 K to 522.35 K
   Pressure = 0.8 MPa to 5.9 Mpa
   Concentration = c₂/mol dm^-3 = 0 and 4.19

Prepared By:
   Pirketta Scharlin

Experimental Remarks:

   Salton Sea geothermal brine (SSGB) was a synthetic brine based on Helgeson's analysis of unflashed hypersaline brine from geothermal well IID-2 which is located in the Imperial Valley of California (Helgeson, H. C., Am. J. Sci. 1968, 266, 129-166).
Detailed composition for the SSGB is given in Table 1.
The pH (measured at 25°C) of SSGB is 4.6. For experimental purposes the pH of the brine was adjusted to neutral by the addition of NaOH.
The synthetic SSGB was prepared from chloride salts of the constituent metal ions, sodium silicate, sodium sulfide, and sodium metaborate, in sccordance with the composition given in Table 1.

Experimental Data:   (Subscripts 1,2,3, ..., in column headings refer to components 1,2,3, ...)


Chemical Name	Concentration C₁ [ppm]
Ba	250
B	390
Ca	28 800
Cs	20
Cl	155 000
Cu	3 (a)
Fe	2000
Pb	80
Li	210
Mg	10
Mn	1 370
K	16 500
Rb	70
SiO<2>	400
Ag	<1 (a)
Na	53 000
Sr	440
S	30
Zn	500

Table 2. Mean experimental values/of the Henry’s law constant KH.
t/°C	T/K	Pressure	Henry's law constant, K [Mpa]	Henry Constant Note	Concentration C₂ [mol/dm³]	Molality m₂ [mol/kg]
33	306.15	0.8	206	(b)	0	0
126.3	399.45	2.0	602	(b)	0	0
132.5	405.65	2.0	617	(b)	0	0
146.0	419.15	2.8	565	(b)	0	0
153.5	426.65	3.1	580	(b)	0	0
198.1	471.25	4.1	537	(b)	0	0
213.1	486.25	5.8	484	(b)	0	0
4.9	278.05	1.8	363	(b)	4.19	4.87
5.0	278.15	1.8	333	(b)	4.19	4.87
11.7	248.85	1.5	392	(b)	4.19	4.87
26.4	299.55	1.2	575	(b)	4.19	4.87
39	312.15	1.9	670	(b)	4.19	4.87
60.4	333.55	1.7	951	(b)	4.19	4.87
75.4	348.55	2.1	1144	(b)	4.19	4.87
97	370.15	2.1	1506	(b)	4.19	4.87
124.2	397.35	2.2	1622	(b)	4.19	4.87
137.1	410.25	2.2	2109	(b)	4.19	4.87
156.3	429.45	1.5	1938	(b)	4.19	4.87
159	432.15	2.5	1833	(b)	4.19	4.87
199.8	472.95	3.9	1702	(b)	4.19	4.87
228.6	501.75	4.9	2081	(b)	4.19	4.87
249.2	522.35	5.9	2182	(b)	4.19	4.87

Notes:
   Table 1  ^a  Not included in synthetic brine.
   Table 2  ^a  Calculated by the compiler.
   Table 2  ^b  K_H = P_1^Ø1/x₁, where K_H = Henry's law constant, P₁ = partial pressure of gas (P₁ = P - P₂; P₂ is the vapor pressure of water at the corresponding temperature), Ø₁ = fugacity coefficient (Smith, J.M. and Van Ness, H.C. Chemical Engineering Thermodynamics, McGraw-Hill, New York 1959), and x₁ = mole fraction of the dissolved CO₂.

Method/Apparatus/Procedure:
   The solubility of CO₂ was determined from pressure-volume-temperature (PVT) measurements using the technique of gas extraction. The apparatus consisted of (1) a high-pressure, high-temperature section for dissolving the gas in the brine, (2) a heat exchanger or cooling (or heating) samples of gas-saturated brine to room temperature, and (3) a low-pressure, constant temperature section for making PVT measurements on collected gas and liquid samples.
A two liter, type 316 stainless steel stirred reactor, fitted with a heat and chemical-resistant glass liner, was filled two-thirds full with brine. The brine was deaerated by evacuating the reactor to the vapor pressure of the brine for at least 3 minutes. Upon reaching thermal equilibrium, the gas was injected into the reactor and allowed to distribute at a fixed partial pressure between the vapor and liquid phases. Equilibration occurred within 5 hours at 150 °C and above, and within 24 hours at lower temperatures. The concentration of CO₂ in the liquid was determined by desorption from a known volume of liquid followed by volumetric analysis of the evolved gas.

Source and Purity of Materials:
   (1) 99.5 %.
   (2) Prepared from reagent grade chemicals.
   (3) Demineralized.

Estimated Errors:

   Temperature: δK_H/K_H = 0.058 (by author)
(Detailed analysis of experimental contributions to the total error is given in the source.)