Сверхкритические флюиды. Теория и практика
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2013, N2, pp. 77-83

M. A. Urusova, V. M. Valyashko

Solubility of NaF and Li2CO3 (salts of type 2) in supercritical water and aqueous electrolyte (NaCl, Na2WO4, Li2SO4) solutions

Experimental studies of binary and ternary water-salt systems containing NaF or Li2CO3 demonstrate that these salts belong to the type 2, which is characterized by negative temperature coefficient of salt solubility in water, by critical phenomena in salt-saturated aqueous solutions and by a wide region of fluid equilibria where homogeneous supercritical fluid solutions are stable at any pressure variation. However, the behavior of these two salts of type 2 differs from that of alkali metals sulfates and carbonates, which is complicated by immiscibility phenomena in stable and metastable states. It is shown that the immiscibility phenomena in hydrothermal binary systems with NaF and Li2CO3 are absent and the second critical end-point Q in solid saturated solutions appears at very high temperature and pressure (above 500 °C and 150 MPa).

Key words: aqueous solutions of NaF and Li2CO3, salt solubility and critical phenomena in binary and ternary systems


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