K2SO4-K2HPO4-H2O phase diagram in the region of heterogeneous supercritical fluids

Urusova, M. A.; Valyashko, V. M.

doi:10.1134/s0036023608040219

Cited by 10 publications

(3 citation statements)

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“…15 and 333.15) K by the method of isothermal solution saturation and moist residues. (K 2 SO 4 + KH 2 PO 4 + H 2 O) phase diagram in the region of heterogeneous supercritical fluids has been reported in the literature [11]. The phase equilibrium data for the ternary system http 15) K have been reported in the literature [12].…”

Section: Introductionmentioning

confidence: 98%

Stable (solid+liquid) phase equilibrium for the ternary systems (K2SO4+KH2PO4+H2O), (K2SO4+KCl+H2O) at T=313.15K

Shen

Ren

Wang

et al. 2015

The Journal of Chemical Thermodynamics

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Section: Introductionmentioning

confidence: 98%

Stable (solid+liquid) phase equilibrium for the ternary systems (K2SO4+KH2PO4+H2O), (K2SO4+KCl+H2O) at T=313.15K

Shen

Ren

Wang

et al. 2015

The Journal of Chemical Thermodynamics

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“…If an unsat urated fluid separates into two immiscible solutions or a solid phase crystallizes from the fluid solution, then the solution composition at the pressure found in this way (at the moment when a second phase appears) corresponds to the feed composition. If a saturated fluid separates (in the presence of a solid phase), then the composition of the newly appearing saturated solution is unknown, but it can be found graphically, from a set of experiments, as a result of constructing р-Х curves, which reflect how the found equilibrium pressures depend on the content of one salt at a set ratio of the two components [11][12][13][14][15][16][17]. In some cases, p-V curves reveal two inflections.…”

mentioning

confidence: 99%

“…The experimental methods described in [1] and in our earlier studies of three component water-salt sys tems [11][12][13][14][15][16][17], consisted of the determination of phase transition pressures using an autoclave equipped with a mercury seal where the volume of the mixture was increased by means of mercury release at T = const. Pressure was measured with a 100 MPa pressure gage (having 1 accuracy class); temperature was measured by a Chromel-Alumel thermocouple (with an error of ±0.5 K).…”

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confidence: 99%

Phase equilibria and critical phenomena in the Li2SO4-K2SO4-H2O system at 380-400°C: Specifics of ternary phase diagrams with type 2 (p-Q) boundary subsystems

Urusova

Valyashko

2012

Russ. J. Inorg. Chem.

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579This work is focused on the transition from super critical (SC) fluid equilibria, where the fluid solution (fl) remains homogeneous at any pressure, to hetero geneous SC equilibria l 1 /g/-l 2 an l 1 /g/-l 2 -s in response to changing mixture composition. The sub ject matter of the study at 380-400°С was the Li 2 SO 4 -K 2 SO 4 -H 2 O three component system, where both water-salt boundary subsystems (Li 2 SO 4 -Н 2 О and K 2 SO 4 -H 2 O) are type 2 (p-Q) systems, i.e., systems where heterogeneous gas-liquid equilibria at temper atures above the critical point of the volatile compo nent (water) are interrupted by a region of homoge neous SC fluids [1][2][3].Another specific feature of this ternary system is the existence of double salt KLiSO 4 , which is stable over a wide range of parameters of state, is congruently solu ble at elevated temperatures (>100°C), and forms a type 2 (p-Q) binary system with water [4][5][6]. For these reasons, the Li 2 SO 4 -K 2 SO 4 -H 2 O system may be represented as two similar (2-2-1 class in the sys tematic [2, 3]) ternary systems (Li 2 SO 4 -KLiSO 4 -H 2 O and K 2 SO 4 -KLiSO 4 -H 2 O), each to be studied individually. Some hydrothermal equilibria in the K 2 SO 4 -KLiSO 4 -H 2 O system have been studied ear lier [7,8].Li 2 SO 4 -H 2 O, K 2 SO 4 -H 2 O, and KLiSO 4 -H 2 O binary systems, as the vast majority of type 2 (p-Q) water-salt systems, are characterized by two critical end points (point p (g = l-s) and point Q (l 1 =l 2 -s) (from this, p-Q type systems), and by fluid regions at temperatures between T p and T Q where, whatever the pressure, the fluid does not separate into two phases (g-l or l 1 -l 2 ) and a crystalline salt can be in equilib rium only with the homogeneous fluid. Temperatures T p at which three phase equilibria g-l-s end and SC fluid equilibria appear, in all three of the binary sys tems are close to the critical point of water (374°С); the solubilities of salts under these conditions are very low (<2.5 wt %) [1-3]. Temperatures T Q and pressures р Q with which fluid equilibria (fl-s) are changed by equilibria l 1 -l 2 -s, are different in the aforementioned systems: 386°С and 59 MPa (KLiSO 4 -H 2 O), 395°С and 83 MPa (Li 2 SO 4 -H 2 O), and 430°С and 66 MPa (K 2 SO 4 -H 2 O). Salt concentrations in the critical solutions (l 1 = l 2 -s) of these systems are 30 ± 3 wt %, or 5 ± 0.5 mol % KLiSO 4 , 6.6 ± 0.6 mol % Li 2 SO 4 , 4.2 ± 0.4 mol % K 2 SO 4 [1-3, 6, 9, 10].At temperatures above T Q , the solubility iso therms/polybars of type 2 salts in water reveal a jump in the concentration of saturated liquid solutions in crossing the stable immiscibility region l 1 -l 2 -s. This can be seen in Fig. 1, which shows the compositions of coexisting saturated and unsaturated solutions in the Li 2 SO 4 -Н 2 О and KLiSO 4 -H 2 O systems at 400°С. The salt content of a dilute solution (l 1 ) is not high; under isothermal pressure reduction, this phase is continuously converting into a vapor solution (g) in equilibrium with a type 2 salt. The second liquid phase (l 2 ...

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Inorganic salts crystallization and deposition characteristics and mechanisms in supercritical water

Yang

Xu²,

Jiang³

et al. 2022

Desalination

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K2SO4-K2HPO4-H2O phase diagram in the region of heterogeneous supercritical fluids

Cited by 10 publications

References 5 publications

Stable (solid+liquid) phase equilibrium for the ternary systems (K2SO4+KH2PO4+H2O), (K2SO4+KCl+H2O) at T=313.15K

Stable (solid+liquid) phase equilibrium for the ternary systems (K2SO4+KH2PO4+H2O), (K2SO4+KCl+H2O) at T=313.15K

Phase equilibria and critical phenomena in the Li2SO4-K2SO4-H2O system at 380-400°C: Specifics of ternary phase diagrams with type 2 (p-Q) boundary subsystems

Inorganic salts crystallization and deposition characteristics and mechanisms in supercritical water

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