Appendix
14. Appendix
14.1 Substances and solvents
Magnesium sulfate hydrates
Transition point: MgSO4 • 7H2O ↔ MgSO4 • 6H2O at 48.1°C /OTT02/
MgSO4 • 7H2O
Magnesium sulfate heptahydrate
Mineral name:
Mol wt:
Purchased from:
epsomite
246.48
Merck (pure)
100 µm
MgSO4 • 7H2O crystals
MgSO4 • 6H2O
Magnesium sulfate hexahydrate
Mineral name:
Mol wt:
Purchased from:
hexahydrite
228.47
Fluka (puriss. p.a.)
100 µm
MgSO4 • 6H2O crystals
113
Appendix
Zinc sulfate hydrates
Transition point: ZnSO4 • 7H2O ↔ ZnSO4 • 6H2O at 39.0°C /ROH02/
ZnSO4 • 7H2O
Zinc sulfate heptahydrate
Mineral name:
Mol wt:
Purchased from:
zinc vitriol
287.55
Merck (pure)
100 µm
100 µm
ZnSO4 • 7H2O crystals
L-Phenylalanine
Transition point C9H11NO2 • H2O ↔ C9H11NO2 at 37.0°C /MOHN01/
C9H11NO2 or C6H5CH2CH(NH2)CO2H
L-Phenylalanine anhydrate
Mol wt:
Purchased from:
165.19
Lancaster (assay, formula >99%)
100 µm
C9H11NO2 crystals
114
Appendix
Borax hydrates
Transition point: Na2B4O7 • 10H2O ↔ Na2B4O7 • 5H2O at 60.8°C /SMI02/
Na2B4O7 • 10H2O
di-Sodium tetraborate decahydrate
Mineral name:
Mol wt:
Purchased from:
tincal, borax
381.37
Merck (extra pure)
100 µm
Na2B4O7 • 10H2O crystals
Calciumchloride hydrates
Transition point CaCl2 • 4H2O ↔ CaCl2 • 2H2O at 45.3°C /KEM02/
CaCl2 • 2H2O
Calciumchloride dihydrate
Mineral name:
Mol wt:
Purchased from:
sinjarite
147.02
Merck (cryst. GR for analysis)
100 µm
CaCl2 • 2H2O crystals
115
Appendix
Stearic acid
Transition point B ↔ C between 29-32°C /BEC84, SAT84, SAT85/
C18H36O2
Stearic acid
Mol wt:
Purchased from:
284.47
Merck
100 µm
stearic acid crystals
Methanol
Methanol, dried, max. 0.005% H2O, Merck
116
Appendix
14.2 Additives
CaSO4 • 2H2O
Calcium sulfate dihydrate, Merck (precipitated, GR for analysis)
FeSO4 • H2O
Iron(II) sulfate hydrate, Merck (extra pure)
H2SO4
Sulfuric acid, Merck (95-98%, extra pure)
KCl
Potassium chloride, Merck (GR for analysis)
KH2PO4
Potassium dihydrogen phosphate, Merck (GR for analysis)
K2SO4
Potassium sulfate, Merck (cryst. GR for analysis)
MgCl2
Magnesium chloride, Merck (anhydrous, for synthesis)
Na2B4O7 • 10H2O
di-Sodium tetraborate decahydrate, Merck (GR for synthesis)
NaCl
Sodium chloride, Merck (extra pure)
NaOH
Sodium hydroxide, Riedel-de Haën (GR for analysis)
Na2SO4
Sodium sulfate, Riedel-de Haën (anhydrous, GR for analysis)
NiSO4 • 6H2O
Nickel(II) sulfate hexahydrate, Merck (GR for analysis)
117
Appendix
14.3 Ultrasonic velocity of magnesium sulfate solutions
magnesium sulfate solutions for concentrations between
2100
2100
2050
2050
2000
2000
1950
1950
1900
1900
1850
1850
1800
1800
1750
1750
10 0
2
tem 30 0
pera 4
ture 50 0
[°C] 6
70
80 25
ultrasonic velocity [m/s]
ultrasonic velocity [m/s]
Ultrasonic velocity of
25 and 48 wt%.
45
40
[-]
35
on
i
t
a
tr
30
cen
con
The ultrasonic velocity y in aqueous magnesium sulfate solutions in dependence on
temperature x1 and concentration x2 can be correlated by the following equation:
y = a + b x 1 + c x 2 + d x 12 + e x 22 + f x 1 x 2
Variables for concentrations between 0-25 and 25-48 wt% magnesium sulfate
variables
a
b
c
d
e
f
concentration
0-25 wt%
(R2 = 0.9994)
25-48 wt%
(R2 = 0.9993)
1409.648757
4.048246101
11.55346016
-0.02739812
0.05267242271
-0.06127042746
1335.664605
2.826807026
17.96038865
-0.0151228834
-0.06620185994
-0.05364606128
118
Appendix
14.4 Solubility of magnesium sulfate in aqueous solution
Comparison between own experimental data (exp.) and data from literature (lit.) /SEI65/.
concentration [MgSO4 / 100 H2O]
60
55
epsomite - lit.
epsomite - exp.
hexahydrite - lit.
hexahydrite - exp.
50
45
40
35
30
25
10
20
30
40
50
temperature [°C]
Solubility of epsomite
saturation temperature [°C]
(exp.)
(lit.)
concentration [g anh. / 100g H2O]
20.1
30.5
42.0
50.0**
55.0**
60.0**
33.69
38.89
44.51
50.38
52.67
55.04
20.0
30.0
40.0
----
Solubility of hexahydrite
saturation temperature [°C]
(exp.)
(lit.)
concentration [g anh. / 100g H2O]
20.0**
30.0**
40.0**
50.5
56.0
60.2
37.93
40.06
44.72
50.15
52.21
54.32
---50.0
55.0
60.0
** solubility of the metastable phase
119
60
Appendix
Supersolubility of epsomite
concentration
[g anh. / 100g H2O]
33.69
38.89
44.51
50.38
saturation
temperature [°C]
20.1
30.5
42.0
50.0
nucleation
temperature [°C]
14.3
26.9
38.8
47.9
∆Tmax*
[K]
5.8
3.6
3.2
2.1
nucleation
temperature [°C]
45.6
48.4
53.4
58.0
∆Tmax*
[K]
2.2
2.1
2.6
2.2
Supersolubility of hexahydrite
concentration
[g anh. / 100g H2O]
49.25
50.15
52.21
54.32
saturation
temperature [°C]
47.8
50.5
56.0
60.2
* average of 3-5 measurements with ultrasound, 10 K / h, seed crystal, moderate
stirring
120
Appendix
14.5 Influence of additives on the solubility of magnesium sulfate
Additive
--
Concentration
[wt%]
pH: 6.4
Saturation temperature
[°C]
30.5
CaSO4 • 2H2O
FeSO4 • H2O
0.1
1
30.6
30.8
H2SO4
KCl
KCl
KCl
pH: 2.5
0.5
1.5
2
30.8
30.5
30.5
30.5
KH2PO4
K2SO4
K2SO4
1
2
5
30.1
30.3
29.4
MgCl2
MgCl2
MgCl2
0.1
1
2
30.8
31.3
32.8
Na2B4O7 • 10H2O
Na2B4O7 • 10H2O
Na2B4O7 • 10H2O
Na2B4O7 • 10H2O
Na2B4O7 • 10H2O
Na2B4O7 • 10H2O
0.1
0.5
1
2
3.5
5
30.5
30.4
30.2
30.1
29.1
28.6
NaCl
NaCl
2
5
31.6
32.5
NaOH
pH: 7.7
30.2
Na2SO4
Na2SO4
2
5
30.9
31.9
NiSO4 • 6H2O
1
30.8
121
Appendix
14.6 Metastable zone (maximum allowable
sulfate in aqueous solution with additives
supercooling)
of
magnesium
10
CaSO4 • 2H2O
cooling rate [K/h]
9,5
9
8,5
8
7,5
pure
0.1 wt% CaSO4
7
3
3,2
3,4
3,6
3,8
4
4,2
supercooling [K]
10
FeSO4 • H2O
cooling rate [K/h]
9,5
9
8,5
8
7,5
pure
20 ppm Fe2SO4.H2O
1 t% Fe2SO.H2O4
7
3
3,2
3,4
3,6
3,8
4
4,2
4
4,2
supercooling [K]
10
KH2PO4
cooling rate [K/h]
9,5
9
8,5
8
7,5
pure
1 wt% KH2PO4
7
3
3,2
3,4
3,6
3,8
supercooling [K]
122
Appendix
10
K2SO4
cooling rate [K/h]
9,5
9
8,5
8
7,5
pure
2 wt% K2SO4
5 wt% K2SO4
7
3
3,2
3,4
3,6
3,8
4
4,2
supercooling [K]
10
MgCl2
cooling rate [K/h]
9,5
9
8,5
8
7,5
pure
1 wt% MgCl2
7
3
3,2
3,4
0.1 wt% MgCl2
2 wt% MgCl2
3,6
3,8
4
4,2
supercooling [K]
NaCl
cooling rate [K/h]
10
9,5
9
8,5
8
7,5
pure
2 wt% NaCl
5 wt% NaCl
7
3
3,2
3,4
3,6
3,8
supercooling [K]
123
4
4,2
Appendix
10
Na2SO4
cooling rate [K/h]
9,5
9
8,5
8
7,5
pure
2 wt% Na2SO4
5 wt% Na2SO4
7
3
3,3
3,6
3,9
4,2
4,5
4,8
4
4,2
supercooling [K]
10
NiSO4 • 6H2O
cooling rate [K/h]
9,5
9
8,5
8
pure
7,5
1 wt%
NiSO4.6H2O
7
3
3,2
3,4
3,6
3,8
supercooling [K]
10
pH
cooling rate [K/h]
9,5
9
8,5
8
7,5
pure (pH 6.4)
pH 2.5
pH 7.7
7
2,8
3
3,2
3,4
3,6
supercooling [K]
124
3,8
4
4,2
Appendix
14.7 Solubility of zinc sulfate heptahydrate in aqueous solution
Solubility of zinc sulfate heptahydrate
saturation temperature [°C]
concentration [g anh. / 100g H2O]
10.15
15.45
20.70
25.60
30.40
35.90
38.45
38.70
39.75**
44.00+
47.09
50.33
53.78
57.44
61.28
66.15
68.77
68.58
69.46
72.48
** solubility of the metastable phase
+
solubility of zinc sulfate hexahydrate
Supersolubility of zinc sulfate heptahydrate
concentration
[g anh. / 100g H2O]
saturation
nucleation
∆Tmax*
temperature [°C] temperature [°C] [K]
53.78
57.44
61.28
66.15
20.7
25.6
30.4
35.9
16.95
22.42
27.74
33.32
3.75
3.18
2.66
2.58
* average of 3-5 measurements with ultrasound, 10 K/h, seed crystal, moderate
stirring
125