Chemical Research in Chinese Universities ›› 2017, Vol. 33 ›› Issue (3): 460-465.doi: 10.1007/s40242-017-6275-y

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Measurements and Calculations of Solid-liquid Equilibria in Quaternary System Li2SO4-Na2SO4-K2SO4-H2O at 288 K

CUI Ruizhi, YANG Lei, WANG Wei, SANG Shihua   

  1. College of Materials and Chemistry & Chemical Engineering, Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institutions, Chengdu University of Technology, Chengdu 610059, P. R. China
  • Received:2016-06-28 Revised:2017-02-20 Online:2017-06-01 Published:2017-04-01
  • Contact: SANG Shihua,E-mail:sangsh@cdut.edu.cn E-mail:sangsh@cdut.edu.cn
  • Supported by:

    Supported by the National Natural Science Foundation of China(Nos.U1407108, 41373062) and the Scientific Research and Innovation Team in Universities of Sichuan Provincial Department of Education, China(No.15TD0009).

Abstract:

The isothermal dissolution equilibrium method has been used to investigate the solid and liquid equilibria of quaternary system Li2SO4-Na2SO4-K2SO4-H2O at 288 K. The phase diagram and water diagram were plotted according to the experiment results. It was found that Li2SO4-Na2SO4-K2SO4-H2O quaternary system contains four double salts at 288 K. There are six invariant points, twelve univariant curves and seven areas of crystallization:Li2SO4·H2O, Na2SO4·10H2O, K2SO4, Li2SO4·3Na2SO4·12H2O, Li2SO4·K2SO4, Na2SO4·3K2SO4, 2Li2SO4·Na2SO4· K2SO4. Using the equilibrium solubility data of the quaternary system at 288 K, the solubility product(lnKsp) of solid phase 2Li2SO4·Na2SO4·K2SO4, which is not reported was acquired. Based on the chemical model of Pitzer's electrolyte solution theory, the solubilities for the quaternary system Li2SO4-Na2SO4-K2SO4-H2O at 288 K were calculated with corresponding parameters. Compared the results of experimental measurement with those of calculation, it was shown that the calculated values had a good agreement with the experimental ones.

Key words: Salt-water system, Phase equilibrium, Solubility, Sulfate, Pitzer's equation