Study On Activity Coefficients Of Ternary Sub（?）Systems Of K⁺, Na⁺, Sr²⁺//Cl^-, Br^--H₂O System At 298.15 K

In order to study on thermodynamic properties of containing Strontium systems of underground gas field brine in western Sichuan Basin, this paper determined the mean activity coefficients of four ternary systems NaBr ? SrBr₂ ?H₂O, NaCl ? SrCl₂ ? H₂O, KBr ? SrBr₂ ? H₂O, KCl ? SrCl₂ ? H₂O by Electrode Potential Measurements.The electromotive force of single salts NaBr was measured by Electrode Potential Measurements at 298.15 K at the total ionic strength of 0.0010 ? 2.5000mol·kg–1, study found that the experimental results has a good linear response relationship, meet the demand of experiment. The electromotive force of NaBr ? SrBr₂ ? H₂O mixed salts was measured by Electrode Potential Measurements at the total ionic strength of 0.0100 ? 2.5000mol·kg–1 at 298.15 K. According to the EMF values the mean activity coefficients were obtained. And then we used the linear regression method（MATLAB） to obtaine Pitzer parameters for NaBr ? SrBr₂ ? H₂O mixed solutions according to the values for mean activity coefficient, those parameters obtained with the Pitzer model were used to calculate the values of the permeability coefficients, water activity, the excess Gibbs free energy of the Na Br ? SrBr₂ ? H₂O systems.The electromotive force of single salts NaCl was measured by Electrode Potential Measurements at 298.15 K at the total ionic strength of 0.0010 ? 5.0000mol·kg–1, study found that the experimental results has a good linear response relationship, meet the demand of experiment. The electromotive force of NaCl ? SrCl₂ ? H₂O mixed salts was measured by Electrode Potential Measurements at the total ionic strength of 0.0100 ? 4.5000mol·kg–1 at 298.15 K. According to the EMF values the mean activity coefficients were obtained. And then we used the linear regression method（MATLAB） to obtaine Pitzer parameters for NaCl ? SrCl₂ ? H₂O mixed solutions according to the values for mean activity coefficient, those parameters obtained with the Pitzer model were used to calculate the values of the permeability coefficients, water activity, the excess Gibbs free energy of the NaCl ? SrCl₂ ? H₂O systems.The electromotive force of single salts KBr was measured by Electrode Potential Measurements at 298.15 K at the total ionic strength of 0.0010 ? 2.0000mol·kg–1, study found that the experimental results has a good linear response relationship, meet the demand of experiment. The electromotive force of KBr ? SrBr₂ ? H₂O mixed salts was measured by Electrode Potential Measurements at the total ionic strength of 0.0100 ? 2.0000mol·kg–1 at 298.15 K. According to the EMF values the mean activity coefficients were obtained. And then we used the linear regression method（MATLAB） to obtaine Pitzer parameters for KBr ? Sr Br2 ? H₂O mixed solutions according to the values for mean activity coefficient, those parameters obtained with the Pitzer model were used to calculate the values of the permeability coefficients, water activity, the excess Gibbs free energy of the KBr ? SrBr₂ ? H₂O systems.The electromotive force of single salts KCl was measured by Electrode Potential Measurements at 298.15 K at the total ionic strength of 0.0010 ? 3.0000mol·kg–1, study found that the experimental results has a good linear response relationship, meet the demand of experiment. The electromotive force of KCl ? SrCl₂ ? H₂O mixed salts was measured by Electrode Potential Measurements at the total ionic strength of 0.0100 ? 3.0000mol·kg–1 at 298.15 K. According to the EMF values the mean activity coefficients were obtained. And then we used the linear regression method（MATLAB） to obtaine Pitzer parameters for KCl ? SrCl₂ ? H₂O mixed solutions according to the values for mean activity coefficient, those parameters obtained with the Pitzer model were used to calculate the values of the permeability coefficients, water activity, the excess Gibbs free energy of the KCl ? SrCl₂ ? H₂O systems.We have drawn four diagrams of the ionic strength scores and the mean activity coefficients according to the experimental results. The experimental results show that the activity coefficients decreased with the increase of the ionic strength, and this change trend is broadly in line with the activity coefficient and ionic strength of the single salt. The diagrams of the osmotic coefficients for the mixed electrolyte system and the total ionic strength of systems were drawn. The diagrams of the solvent activity for the mixed electrolyte system and the total ionic strength of systems were drawn. The diagrams of the excess Gibbs free energy for the mixed electrolyte system and the total ionic strength of systems were drawn.