چكيده به لاتين
One of the most common gases which has the capability of dissolving in electrolyte solutions is CO2. In this thesis, the CO2 solubility in some strong electrolyte solutions has been scrutinized and comparison with experimental solubility data from aqueous solutions containing single and mixed salts have been made.
Generally, electrolyte solutions are formed as a result of solving one or more salts in one or more solvents. Subsequently, Salt dissociates partially or completely and electrolyte solution is formed. In this investigation, Electrolyte SAFT Huang & Radosz EOS which has been extended from SAFT Huang& Radosz by adding Mean Spherical Approximation (MSA), are applied to model CO2 Solubility in electrolytes. In the first step, by using SAFT Huang & Radosz, used for systems with pure component, density and vapor pressure of CO2 are calculated. The Equation of state calculates the density and vapor pressure with average absolute deviations of %Δ𝜌=0.84 𝑎𝑛𝑑 % Δ𝑃𝑆𝑎𝑡=2.64 . In the next stop, The EOS calculates density and vapor pressure of H2O with an average absolute deviations of %Δ𝜌=3.12 𝑎𝑛𝑑 %Δ𝑃𝑆𝑎𝑡=1.23 . In the upcoming stage, by applying SAFT Huang & Radosz for systems with more than one component, investigation on the solubility of CO2 in H2O-CO2 system has been carried out. After being sure about the outcome of this model, The MSA term has been added to the Eos to apply it to model CO2 solubility in aqueous electrolyte solutions. Then, the extended EOS has been applied to calculate equilibrium pressure of dissolved CO2 in strong aqueous electrolyte solutions including: Sodium Chloride, Potassium Chloride, Calcium Chloride, Sodium Sulfate, Potassium Sulfate and systems containing mixed salts including: Sodium Chloride-Potassium Chloride, Sodium Chloride-Potassium Chloride and Potassium Chloride-Calcium Chloride.
In the section of modeling, Electrolyte SAFT Huang & Radosz calculates equilibrium pressure of dissolved CO2 in H2O-CO2-NaCl system with salt concentration 10% (weight fraction) at 318.15 K and pressure range 40.9-158.3. The Average absolute deviations of vapor pressure calculated by eSAFT-HR in comparison with experimental data is 3.11%. The e SAFT-HR estimates CO2 Solubility in electrolytes at concentration of 0.25,0.50 and 1.00 molal of NaCl in the temperature range of 293-353 K and CO2 concentrations of 0.007,0.012 and 0.017 (mole fraction). The result of average absolute deviation of equilibrium pressure estimation in three concentrations of NaCl mentioned are 7.66%, 3.56% and 4.72%. Next, CO2 Solubility in electrolyte contains KCl 10% (wt%) at 318.15 K and pressure range 41.5 to 139.9 bar has been surveyed. The AAD% of calculated equilibrium pressure is 3.96%. In the next step, CO2 Solubility in system contains CaCl2 10% (wt%) has been investigated. The EOS estimates equilibrium pressure with AAD%=3.09. Then, the results of calculated equilibrium pressure for system contains Na2SO4 1.011 molal at 353.15 K is 10.46%. Then CO2 Solubility in electrolyte containing K2SO4 is compared with experimental results of CO2 Solubility at 298.15 K and pressure 1.01 bar. At last. Electrolyte SAFT Huang & Radosz predicts CO2 Solubility in aqueous electrolytes containing mixed salts including: NaCl-KCl, NaCl-CaCl2 and KCl-CaCl2. The Average absolute deviations of equilibrium pressure calculated for determined systems at concentration of 10% (wt%) of each mixed salts at temperature 318.15 K have been 13.29%, 14.86% and 12.87%.
Keywords: Electrolyte Solution, CO2 Solubility, Thermodynamic modeling, Electrolyte SAFT Huang & Radosz, Equation of State
