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Table 3 Reactions considered in the HYDROGEOCHEM 5.0 model

From: Influences of specific ions in groundwater on concrete degradation in subsurface engineered barrier system

Aqueous complexation reactions (25 °C)

No.

Reaction

log K

No.

Reaction

log K

1

H2O = OH + H+

−14

20

K+ + Cl = KCl

−1.49

2

Al3+ + 4OH = AlO2  + 2H2O

33.12

21

K+ + OH = KOH

−0.46

3

Al(OH)2+ = Al3+ + 2(OH)

−3.41

22

K+ + SO4 2− = KSO4

0.85

4

Al(OH)2+ = Al3+ + (OH)

−9.05

23

NaAlO2 + 2H2O = Al3+ + Na+ + 4OH

−18.37

5

Al(SO4) 2  = Al3+ + 2SO4 2−

−4.9

24

Na+ + Cl = NaCl

−0.78

6

AlSO2 + = Al3+ + SO4 2−

−3.01

25

NaHCO3 = HCO3  + Na+

−0.15

7

Ca+2 + HCO3  + OH = CaCO3 + H2O

6.895

26

Na+ + H4SiO4 + OH = NaH3SiO4(aq) + H2O

5.99

8

Ca2+ + Cl = CaCl+

−0.7

27

Na+ + HCO3  + OH = NaCO3  + H2O

4.19

9

CaCl2 = Ca2+ + 2Cl

0.64

28

Na+ + OH = NaOH

−0.79

10

CaHCO3 + = Ca2+ + HCO3

−1.05

29

Na+ + SO4 2− = NaSO4

0.82

11

Ca2+ + OH = CaOH+

−1.15

30

HCO3  + 9 H+ + 8 e = CH4(aq) + 3 H2O

30.742

12

Ca2+ + SO4 2− = CaSO4

2.11

31

2 H2O = O2(aq) + 4 H+ + 4 e

−86.08

13

HCO3  = CO2(aq) + OH

7.66

32

2 H+ + 2 e = H2(aq)

−3.15

14

HCO3  + OH = CO3 2− + H2O

−3.67

33

SO4 2− + 8 H+ + 8 e = S2− + 4 H2O

20.732

15

HAlO2(aq) + H2O = Al3+ + 3(OH)

−25.57

34

SO4 2− + 9 H+ + 8 e = HS + 4 H2O

33.65

16

HCl +OH = Cl + H2O

13.33

35

SO4 2− + 10 H+ + 8 e = H2S + 4 H2O

40.644

17

H4SiO4 + 2OH = H2SiO4 2− + 2H2O

5

36

Fe+3 + e = Fe+2

13.02

18

H2SO4 + 2(OH) = SO4 2− + 2H2O

29.02

37

Fe+3 + 4 H2O = Fe(OH) 4  + 4 H+

−21.6

19

HSO4  + OH = H2O + SO4 2−

12.02

   

Precipitation-dissolution reactions (25 °C)

No.

Mineral

Reaction

log K

Molar volume (dm3/mol)

1

Calcite

HCO3  + Ca2+ + OH = CaCO3 + H2O

12.151

0.03693

2

Portlandite

Ca2+ + 2OH = Ca(OH)2

5.20

0.03300

3

Ettringite

2Al3+ + 6Ca2+ + 26H2O + 3SO4 2− + 12OH = Ca6Al2(SO4)3(OH)12·26H2O

111.03

0.71032

4

Quartz

H4SiO4 = SiO2 + 2H2O

3.98

0.02269

5

Gypsum

Ca2+ + SO4 2− + 2H2O = CaSO4·2H2O

4.58

0.07470

6

Hydrogarnet

2Al3+ + 3Ca2+ + 12OH = Ca3Al2(OH)12

87.68

0.14952

7

Friedel’s salt

2Al3+ + 4Ca2+ + 2Cl + 4H2O + 12OH = 2Ca2Al(OH)6Cl·2H2O

93.07

0.27624

8

Thaumasite

3Ca2++H4SiO4 + SO4 2−+HCO3 +11H2O +3OH = CaSiO3·CaSO4·CaCO3·15H2O

31.70

0.32940

9

Monocarboaluminate

2Al2+ +HCO3  + 4Ca2+ + 3.68H2O + 13OH = 3CaO·Al2O3·CaCO3·10.68H2O

101.45

0.26196

10

Pyrite

FeS2 + 2 H+ + 2 e = Fe+2 + 2 HS

−18.479

0.02394