Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (02): 181-184.doi: 10.3866/PKU.WHXB20030220

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The Kinetics of Dissolution and Phase Transformation of 2MgO•2 B2O3•MgCl2•14H2O in Water at 87 ℃

Li Xiao-Ping;Liu Zhi-Hong;Gao Shi-Yang;Hu Man-Cheng;Xia Shu-Ping;   

  1. College of Chemistry and Materials Science, Shaanxi Normal University, Xi’an 710062; Xi’an Branch, Institute of Salt Lakes,Chinese Academy of Sciences, Xi’an 710043
  • Received:2002-06-18 Revised:2002-09-20 Published:2003-02-15
  • Contact: Liu Zhi-Hong

Abstract: The kinetics of dissolution and phase transformation of 2MgO•2B2O3•MgCl2•14H2O in water at 87 ℃ were studied. The results of liquid phases anlysized at a given time intervals and solid phases identified by IR and XRD show that 2MgO•2 B2O3•MgCl2•14H2O dissolved incongruently in water and the process was not the same at low temperature, a new crystal midproduct (MgO•B2O3•4H2O) was formed, the final solid phase was pinnoite (MgO•B2O3•3H2O). With the aid of Simplex Optimum Method and Runge-Kutta Digital Solution of differential equation system, the experimental data was fitted. The kinetic equation of the crystallization reaction was given and a mechanism of crystallization reaction was proposed.

Key words: Chloropinnoite(2MgO•, 2 B2O3•, MgCl2•, 14H2O), Hydrated borate, Dissolution kinetics, Phase transformation