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Title: CO 2 solubility in aqueous solutions containing Na + , Ca 2+ , Cl - , SO 4 2- and HCO 3 - : The effects of electrostricted water and ion hydration thermodynamics

Abstract

Dissolution of CO2 into deep subsurface brines for carbon sequestration is regarded as one of the few viable means of reducing the amount of CO2 entering the atmosphere. Ions in solution partially control the amount of CO2 that dissolves, but the mechanisms of the ion's influence are not clearly understood and thus CO2 solubility is difficult to predict. In this study, CO2 solubility was experimentally determined in water, NaCl, CaCl2, Na2SO4, and NaHCO3 solutions and a mixed brine similar to the Bravo Dome natural CO2 reservoir; ionic strengths ranged up to 3.4 molal, temperatures to 140 °C, and CO2 pressures to 35.5 MPa. Increasing ionic strength decreased CO2 solubility for all solutions when the salt type remained unchanged, but ionic strength was a poor predictor of CO2 solubility in solutions with different salts. A new equation was developed to use ion hydration number to calculate the concentration of electrostricted water molecules in solution. Dissolved CO2 was strongly correlated (R2 = 0.96) to electrostricted water concentration. Strong correlations were also identified between CO2 solubility and hydration enthalpy and hydration entropy. These linear correlation equations predicted CO2 solubility within 1% of the Bravo Dome brine and within 10% of two mixed brinesmore » from literature (a 10 wt % NaCl + KCl + CaCl2 brine and a natural Na+, Ca2+, Cl- type brine with minor amounts of Mg2+, K+, Sr2+ and Br-).« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Frontiers of Subsurface Energy Security (CFSES)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1371169
DOE Contract Number:  
SC0001114
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Geochemistry; Journal Volume: 67; Related Information: CFSES partners with University of Texas at Austin (lead); Sandia National Laboratory
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Carbon sequestration; Hydration energy; Hydration number; Dissolved CO2; Bravo Dome

Citation Formats

Gilbert, Kimberly, Bennett, Philip C., Wolfe, Will, Zhang, Tongwei, and Romanak, Katherine D. CO 2 solubility in aqueous solutions containing Na + , Ca 2+ , Cl - , SO 4 2- and HCO 3 - : The effects of electrostricted water and ion hydration thermodynamics. United States: N. p., 2016. Web. doi:10.1016/j.apgeochem.2016.02.002.
Gilbert, Kimberly, Bennett, Philip C., Wolfe, Will, Zhang, Tongwei, & Romanak, Katherine D. CO 2 solubility in aqueous solutions containing Na + , Ca 2+ , Cl - , SO 4 2- and HCO 3 - : The effects of electrostricted water and ion hydration thermodynamics. United States. doi:10.1016/j.apgeochem.2016.02.002.
Gilbert, Kimberly, Bennett, Philip C., Wolfe, Will, Zhang, Tongwei, and Romanak, Katherine D. Fri . "CO 2 solubility in aqueous solutions containing Na + , Ca 2+ , Cl - , SO 4 2- and HCO 3 - : The effects of electrostricted water and ion hydration thermodynamics". United States. doi:10.1016/j.apgeochem.2016.02.002.
@article{osti_1371169,
title = {CO 2 solubility in aqueous solutions containing Na + , Ca 2+ , Cl - , SO 4 2- and HCO 3 - : The effects of electrostricted water and ion hydration thermodynamics},
author = {Gilbert, Kimberly and Bennett, Philip C. and Wolfe, Will and Zhang, Tongwei and Romanak, Katherine D.},
abstractNote = {Dissolution of CO2 into deep subsurface brines for carbon sequestration is regarded as one of the few viable means of reducing the amount of CO2 entering the atmosphere. Ions in solution partially control the amount of CO2 that dissolves, but the mechanisms of the ion's influence are not clearly understood and thus CO2 solubility is difficult to predict. In this study, CO2 solubility was experimentally determined in water, NaCl, CaCl2, Na2SO4, and NaHCO3 solutions and a mixed brine similar to the Bravo Dome natural CO2 reservoir; ionic strengths ranged up to 3.4 molal, temperatures to 140 °C, and CO2 pressures to 35.5 MPa. Increasing ionic strength decreased CO2 solubility for all solutions when the salt type remained unchanged, but ionic strength was a poor predictor of CO2 solubility in solutions with different salts. A new equation was developed to use ion hydration number to calculate the concentration of electrostricted water molecules in solution. Dissolved CO2 was strongly correlated (R2 = 0.96) to electrostricted water concentration. Strong correlations were also identified between CO2 solubility and hydration enthalpy and hydration entropy. These linear correlation equations predicted CO2 solubility within 1% of the Bravo Dome brine and within 10% of two mixed brines from literature (a 10 wt % NaCl + KCl + CaCl2 brine and a natural Na+, Ca2+, Cl- type brine with minor amounts of Mg2+, K+, Sr2+ and Br-).},
doi = {10.1016/j.apgeochem.2016.02.002},
journal = {Applied Geochemistry},
number = ,
volume = 67,
place = {United States},
year = {Fri Apr 01 00:00:00 EDT 2016},
month = {Fri Apr 01 00:00:00 EDT 2016}
}