ABSTRACT

We have investigated the solubility behavior of calcium sulfate dihydrate (gypsum, CaSO4*2H2O) in aqueous NaCl solutions upon addition of ammonium or imidazolium based ionic liquids (ILs) viz. ethylammonium lactate (EAL) and hydroxyethylammonium lactate (HOEAL), 1-ethyl-3-methyl imidazolium hydrogensulfate ([C2mim]HSO4) and 1-butyl-3-methyl imidazolium hydrogensulfate ([C4mim]HSO4) at 30oC. The additions of ammonium lactate ILs increased solubility significantly ~500% while, the addition of imidazolium hydrogensulfate ILs decreased the solubility by ~60%. The addition of ILs shifted the solubility maximum of CaSO4*2H2O either towards higher or lower concentration of NaCl in solution depending upon the nature of IL additive. Solution properties such as density () and speed of sound (u) have been measured for the quaternary systems (CaSO4*2H2O+NaCl+ILs+H2O) at 30C. Solution isentropic compressibility (S) have been derived from measurements of u and . Physical and derived properties have been fitted with suitable polynomial equations. Crystal growth formation and surface morphology of CaSO4*2H2O crystals recrystallized from different aqueous-ILs solutions has also been examined. ILs additives have shown good potential as calcium sulfate scale removal and calcium sulfate precipitation agent.

Compounds

#	Formula	Name
1	CaO4S	calcium sulfate
2	H2O	water
3	C6H12N2O4S	1-ethyl-3-methylimidazolium hydrogen sulfate
4	C8H16N2O4S	1-butyl-3-methylimidazolium hydrogen sulfate
5	C5H13NO3	ethylammonium lactate

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	2 1 5	Molality, mol/kg - 1 ; Liquid	Mass ratio of solute to solvent - 5; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 1	titration and chemical analysis	3
POMD	2 1 5	Mass density, kg/m3 ; Liquid	Mass ratio of solute to solvent - 5; Liquid Molality, mol/kg - 1; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid	Vibrating tube method	3
POMD	2 1 5	Speed of sound, m/s ; Liquid	Mass ratio of solute to solvent - 5; Liquid Molality, mol/kg - 1; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid Frequency, MHz; Liquid	Liquid	Single path-length method	3
POMD	2 1 3	Molality, mol/kg - 1 ; Liquid	Mass ratio of solute to solvent - 3; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 1	titration and chemical analysis	3
POMD	2 1 3	Mass density, kg/m3 ; Liquid	Mass ratio of solute to solvent - 3; Liquid Molality, mol/kg - 1; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid	Vibrating tube method	3
POMD	2 1 3	Speed of sound, m/s ; Liquid	Mass ratio of solute to solvent - 3; Liquid Molality, mol/kg - 1; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid Frequency, MHz; Liquid	Liquid	Single path-length method	3
POMD	2 1 4	Molality, mol/kg - 1 ; Liquid	Mass ratio of solute to solvent - 4; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid Crystal of intercomponent compound 1	titration and chemical analysis	3
POMD	2 1 4	Mass density, kg/m3 ; Liquid	Mass ratio of solute to solvent - 4; Liquid Molality, mol/kg - 1; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid	Liquid	Vibrating tube method	3
POMD	2 1 4	Speed of sound, m/s ; Liquid	Mass ratio of solute to solvent - 4; Liquid Molality, mol/kg - 1; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid Frequency, MHz; Liquid	Liquid	Single path-length method	3

Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

Effect of Ionic Liquid Additives on the Solubility Behavior and Morphology of Calcium Sulfate Dihydrate (Gypsum) in the Aqueous Sodium Chloride System and Physicochemical Solution Properties at 30 deg.C

Shukla, Jignesh, Mehta, Mohit J., Kumar, Arvind

ABSTRACT