ABSTRACT

The solubilities of the quaternary system K2SO4-MgSO4-(NH4)2SO4-H2O were measured by isothermal method at 25 C and their dry salt phase diagrams were plotted. The results indicated that, at 25 C, the solubility phase diagram of this quaternary system consists of seven crystallization regions, those are single-salt crystallization region MgSO4.7H2O, (NH4)2SO4, and K2SO4, complex salt crystallization region MgSO4.(NH4)2SO4.6H2O, MgSO4.K2SO4$6H2O, solid solution crystallization region (K_1-n, NH4n)2SO4 (n:0.143-0.893) and (K_1-n, NH4n)2SO4.MgSO4.6H2O (n:0.552-0.973), respectively. The extended Pitzer model was derived and applied to the phase equilibrium calculation of system K2SO4-MgSO4-(NH4)2SO4-H2O and its sub-systems at 25 C. The results showed that the calculated values were consistent with experimental results well. The study on the quaternary system K2SO4-MgSO4-(NH4)2SO4-H2O provides a foundation for the N-Mg-K-S compound fertilizers preparation.

Compounds

#	Formula	Name
1	MgO4S	magnesium sulfate
2	H2O	water
3	H8N2O4S	ammonium sulfate
4	K2O4S	potassium sulfate

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Constraint	Phase	Method	#Points
POMD	1 2 3	Molality, mol/kg - 1 ; Liquid	Molality, mol/kg - 3; Liquid Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal - 3	titration	1
POMD	1 2 3	Molality, mol/kg - 1 ; Liquid	Molality, mol/kg - 3; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 1	titration	5
POMD	1 2 3	Molality, mol/kg - 1 ; Liquid	Molality, mol/kg - 3; Liquid Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal of intercomponent compound 2	titration	1
POMD	1 2 4	Molality, mol/kg - 1 ; Liquid	Molality, mol/kg - 4; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal - 1	titration	4
POMD	1 2 4	Molality, mol/kg - 1 ; Liquid	Molality, mol/kg - 4; Liquid Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal of intercomponent compound 1	titration	1
POMD	1 2 4	Molality, mol/kg - 1 ; Liquid	Molality, mol/kg - 4; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 2	titration	5
POMD	1 2 4	Molality, mol/kg - 1 ; Liquid	Molality, mol/kg - 4; Liquid Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal of intercomponent compound 3	titration	1
POMD	1 2 4	Molality, mol/kg - 1 ; Liquid	Molality, mol/kg - 4; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal - 4	titration	5
POMD	2 4 3	Molality, mol/kg - 3 ; Liquid	Molality, mol/kg - 4; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal - 4	titration	4
POMD	2 4 3	Molality, mol/kg - 3 ; Liquid	Molality, mol/kg - 4; Liquid Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal of intercomponent compound 1	titration	1
POMD	2 4 3	Molality, mol/kg - 3 ; Liquid	Molality, mol/kg - 4; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 2	titration	7
POMD	2 4 3	Molality, mol/kg - 3 ; Liquid	Molality, mol/kg - 4; Liquid Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal of intercomponent compound 3	titration	1
POMD	2 4 3	Molality, mol/kg - 3 ; Liquid	Molality, mol/kg - 4; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal - 3	titration	2
POMD	2 3	Molality, mol/kg - 3 ; Liquid		Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal - 3	titration	2
POMD	1 2	Molality, mol/kg - 1 ; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid		Liquid Crystal - 1	titration	1
POMD	2 4	Molality, mol/kg - 4 ; Liquid		Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal - 4	titration	2

Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

Phase equilibrium of the quaternary system K2SO4-MgSO4-(NH4)2SO4-H2O at 25 C

Xue, C.-Y.[Chun-Yan], Zhao, B.[Bin], Guo, H.-F.[Hong-Fei], Dou, S.-Y.[Shuai-Yong], Cao, J.-L.[Ji-Lin]

ABSTRACT