Chem. J. Chinese Universities ›› 2021, Vol. 42 ›› Issue (10): 3175.doi: 10.7503/cjcu20210334

• Physical Chemistry • Previous Articles     Next Articles

Comprehensive Thermodynamic Model and Polythermal Phase Diagram Prediction of Nitrate Type Brine Systems

WANG Xingfan1, ZHOU Huan1,2(), ZHOU Kuo2, JIN Fenli2, YANG Junfang2   

  1. 1.College of Marine and Environmental Sciences
    2.College of Chemical Engineering and Materials Science,Tianjin Key Laboratory of Brine Resources and Eco?utilization,Tianjin University of Science and Technology,Tianjin 300457,China
  • Received:2021-05-13 Online:2021-10-10 Published:2021-10-10
  • Contact: ZHOU Huan E-mail:zhouhuan@tust.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(U1707602)

Abstract:

Nitrate type aqueous electrolyte systems are encountered in salt lake brine, nitrate industries and wastewater treatment. Due to the high solubility of nitrate, it is still challenging to achieve accurate thermodynamic expression of physical properties and phase equilibrium of nitrate complex electrolyte system. The Na+//NO3-, Cl-, SO42 - -H2O typical system of coal chemical wastewater was selected as the research object. Based on the improved eNRTL model, the comprehensive thermodynamic model of electrolyte system was composed of activity coefficient model, liquid properties model, species thermodynamic data model, and solid-liquid phase equilibrium model. Based on the freezing points, saturated vapor pressure, isobaric molar heat capacity, activity coefficients and osmotic pressure coefficients of binary systems and the isothermal phase equilibrium data of ternary systems, 12 sets of liquid parameters and thermodynamic parameters of 7 solid species were obtained by multi-objective fitting. The complete multi-temperature phase diagrams of 3 binary systems, 3 ternary systems and one quaternary system were calculated and predicted. The applicable temperature reached all the experimental temperature ranges, namely, 254.65—543.15 K, and the applicable concentration reached saturation, the concentration of NaNO3 reached 226.88 mol/kg. The predicted results of multi temperature phase diagrams of ternary and quaternary systems are in good agreement with the experi- mental data. The results expand the expression ability of electrolyte model in ultra-concentrated and multi- temperature complex systems, and the model and parameters can be used in chemical process of nitrate- containing system, wastewater treatment, salt lake brine resource development and other processes.

Key words: Electrolyte solution, eNRTL model, Liquid property, Polythermal phase diagram prediction, Nitrate system

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