Table 1. Open in new tab Overall testing...

Test #	Test conditions	Preexisting ionic strength (moles/m³)	Inferred diffusion coefficient D_i × 10⁻¹¹ (m²/s)	α = D_Fast/D_Slow.
1	Washed Na-bentonite	68.1 (98.7)	KCl (1 M)	DI	600 (no excess salts Na⁺ is the prevalent counterion)	16.0	—	—	16.0	—	1.0
2	68.7 (97.7)	K₂SO₄ (0.5 M)	DI	16.0	—	—	—	8.0	2.0
3	66.0 (97.7)	SrCl₂ (0.5 M)	DI	—	7.5	—	14.5	—	1.9
4	65.3 (97.3)	CsCl (1 M)	DI	—	—	4.0	9.0	—	2.3
5	65.6 (97.0)	KCl (1 M)	K₂SO₄ (0.5 M)	—	—	—	34.0	16.5	2.1
6	67.2 (98.7)	KCl (1 M)	SrCl₂ (0.5 M)	15.5	8.0	—	—	—	1.9
7	64.9 (98.4)	CsCl (1 M)	KCl (1 M)	15.0	—	8.0	—	—	1.9
8	64.9 (98.4)	CsCl (1 M)	SrCl₂ (0.5 M)	—	14.0	7.0	—	—	2.0
9	K-Kaolin	62.0 (99.2)	CsCl (1 M)	DI	48	—	—	4.0	4.0	—	1.0
10	Washed Na-bentonite	64.2 (99.0)	CsCl (1 M), Na₂SO₄ (0.175 M)	Na₂SO₄ (0.175 M)	1,008	—	—	5.5	25.0	—	4.5
11	62.0 (99.8)	CsCl (1 M), Na₂SO₄ (0.25 M)	Na₂SO₄ (0.25 M)	1,281	—	—	5.5	45.0	—	8.2
12	64.9 (96.7)	Cs₂SO₄ (0.5 M), NaCl (0.25 M)	NaCl (0.25 M)	950	—	—	5.5	—	18.0	3.3
13	61.8 (99.6)	Cs₂SO₄ (0.5 M), NaCl (0.5 M)	NaCl (0.5 M)	1,247	—	—	5.0	—	25.0	5.0
14	59.8 (98.9)	CsCl (1 M), NaCl (0.5 M)	NaCl (0.5 M)	1,247	—	—	5.0	45.0	—	9.0

Test #

Test conditions

Preexisting ionic strength (moles/m³)

Inferred diffusion coefficient
D_i × 10⁻¹¹ (m²/s)

α = D_Fast/D_Slow.

Clay

Avg. water content (deg. of sat.) (%)

Left (molality)

Right (molality)

K⁺

Sr²⁺

Cs⁺

Cl⁻

SO₄²⁻

Washed Na-bentonite

68.1 (98.7)

KCl (1 M)

600 (no excess salts
Na⁺ is the prevalent counterion)

16.0

—

16.0

—

1.0

68.7 (97.7)

K₂SO₄ (0.5 M)

16.0

—

8.0

2.0

66.0 (97.7)

SrCl₂ (0.5 M)

—

7.5

—

14.5

—

1.9

65.3 (97.3)

CsCl (1 M)

—

4.0

9.0

—

2.3

65.6 (97.0)

KCl (1 M)

K₂SO₄ (0.5 M)

—

34.0

16.5

2.1

67.2 (98.7)

KCl (1 M)

SrCl₂ (0.5 M)

15.5

8.0

—

1.9

64.9 (98.4)

CsCl (1 M)

KCl (1 M)

15.0

—

8.0

—

1.9

64.9 (98.4)

CsCl (1 M)

SrCl₂ (0.5 M)

—

14.0

7.0

—

2.0

K-Kaolin

62.0 (99.2)

CsCl (1 M)

—

4.0

—

1.0

Washed Na-bentonite

64.2 (99.0)

CsCl (1 M), Na₂SO₄ (0.175 M)

Na₂SO₄ (0.175 M)

1,008

—

5.5

25.0

—

4.5

62.0 (99.8)

CsCl (1 M), Na₂SO₄ (0.25 M)

Na₂SO₄ (0.25 M)

1,281

—

5.5

45.0

—

8.2

64.9 (96.7)

Cs₂SO₄ (0.5 M), NaCl (0.25 M)

NaCl (0.25 M)

950

—

5.5

—

18.0

3.3

61.8 (99.6)

Cs₂SO₄ (0.5 M), NaCl (0.5 M)

NaCl (0.5 M)

1,247

—

5.0

—

25.0

5.0

59.8 (98.9)

CsCl (1 M), NaCl (0.5 M)

NaCl (0.5 M)

1,247

—

5.0

45.0

—

9.0

Test #	Test conditions	Preexisting ionic strength (moles/m³)	Inferred diffusion coefficient D_i × 10⁻¹¹ (m²/s)	α = D_Fast/D_Slow.
1	Washed Na-bentonite	68.1 (98.7)	KCl (1 M)	DI	600 (no excess salts Na⁺ is the prevalent counterion)	16.0	—	—	16.0	—	1.0
2	68.7 (97.7)	K₂SO₄ (0.5 M)	DI	16.0	—	—	—	8.0	2.0
3	66.0 (97.7)	SrCl₂ (0.5 M)	DI	—	7.5	—	14.5	—	1.9
4	65.3 (97.3)	CsCl (1 M)	DI	—	—	4.0	9.0	—	2.3
5	65.6 (97.0)	KCl (1 M)	K₂SO₄ (0.5 M)	—	—	—	34.0	16.5	2.1
6	67.2 (98.7)	KCl (1 M)	SrCl₂ (0.5 M)	15.5	8.0	—	—	—	1.9
7	64.9 (98.4)	CsCl (1 M)	KCl (1 M)	15.0	—	8.0	—	—	1.9
8	64.9 (98.4)	CsCl (1 M)	SrCl₂ (0.5 M)	—	14.0	7.0	—	—	2.0
9	K-Kaolin	62.0 (99.2)	CsCl (1 M)	DI	48	—	—	4.0	4.0	—	1.0
10	Washed Na-bentonite	64.2 (99.0)	CsCl (1 M), Na₂SO₄ (0.175 M)	Na₂SO₄ (0.175 M)	1,008	—	—	5.5	25.0	—	4.5
11	62.0 (99.8)	CsCl (1 M), Na₂SO₄ (0.25 M)	Na₂SO₄ (0.25 M)	1,281	—	—	5.5	45.0	—	8.2
12	64.9 (96.7)	Cs₂SO₄ (0.5 M), NaCl (0.25 M)	NaCl (0.25 M)	950	—	—	5.5	—	18.0	3.3
13	61.8 (99.6)	Cs₂SO₄ (0.5 M), NaCl (0.5 M)	NaCl (0.5 M)	1,247	—	—	5.0	—	25.0	5.0
14	59.8 (98.9)	CsCl (1 M), NaCl (0.5 M)	NaCl (0.5 M)	1,247	—	—	5.0	45.0	—	9.0

Table 1.

Open in new tab

Overall testing conditions and inferred diffusion coefficients.

Test #	Test conditions				Preexisting ionic strength (moles/m³)	Inferred diffusion coefficient D_i × 10⁻¹¹ (m²/s)					α = D_Fast/D_Slow.
Test #	Clay	Avg. water content (deg. of sat.) (%)	Left (molality)	Right (molality)	Preexisting ionic strength (moles/m³)	K⁺	Sr²⁺	Cs⁺	Cl⁻	SO₄²⁻	α = D_Fast/D_Slow.
1	Washed Na-bentonite	68.1 (98.7)	KCl (1 M)	DI	600 (no excess salts Na⁺ is the prevalent counterion)	16.0	—	—	16.0	—	1.0
2		68.7 (97.7)	K₂SO₄ (0.5 M)	DI		16.0	—	—	—	8.0	2.0
3		66.0 (97.7)	SrCl₂ (0.5 M)	DI		—	7.5	—	14.5	—	1.9
4		65.3 (97.3)	CsCl (1 M)	DI		—	—	4.0	9.0	—	2.3
5		65.6 (97.0)	KCl (1 M)	K₂SO₄ (0.5 M)		—	—	—	34.0	16.5	2.1
6		67.2 (98.7)	KCl (1 M)	SrCl₂ (0.5 M)		15.5	8.0	—	—	—	1.9
7		64.9 (98.4)	CsCl (1 M)	KCl (1 M)		15.0	—	8.0	—	—	1.9
8		64.9 (98.4)	CsCl (1 M)	SrCl₂ (0.5 M)		—	14.0	7.0	—	—	2.0
9	K-Kaolin	62.0 (99.2)	CsCl (1 M)	DI	48	—	—	4.0	4.0	—	1.0
10	Washed Na-bentonite	64.2 (99.0)	CsCl (1 M), Na₂SO₄ (0.175 M)	Na₂SO₄ (0.175 M)	1,008	—	—	5.5	25.0	—	4.5
11		62.0 (99.8)	CsCl (1 M), Na₂SO₄ (0.25 M)	Na₂SO₄ (0.25 M)	1,281	—	—	5.5	45.0	—	8.2
12		64.9 (96.7)	Cs₂SO₄ (0.5 M), NaCl (0.25 M)	NaCl (0.25 M)	950	—	—	5.5	—	18.0	3.3
13		61.8 (99.6)	Cs₂SO₄ (0.5 M), NaCl (0.5 M)	NaCl (0.5 M)	1,247	—	—	5.0	—	25.0	5.0
14		59.8 (98.9)	CsCl (1 M), NaCl (0.5 M)	NaCl (0.5 M)	1,247	—	—	5.0	45.0	—	9.0

Test #	Test conditions				Preexisting ionic strength (moles/m³)	Inferred diffusion coefficient D_i × 10⁻¹¹ (m²/s)					α = D_Fast/D_Slow.
Test #	Clay	Avg. water content (deg. of sat.) (%)	Left (molality)	Right (molality)	Preexisting ionic strength (moles/m³)	K⁺	Sr²⁺	Cs⁺	Cl⁻	SO₄²⁻	α = D_Fast/D_Slow.
1	Washed Na-bentonite	68.1 (98.7)	KCl (1 M)	DI	600 (no excess salts Na⁺ is the prevalent counterion)	16.0	—	—	16.0	—	1.0
2		68.7 (97.7)	K₂SO₄ (0.5 M)	DI		16.0	—	—	—	8.0	2.0
3		66.0 (97.7)	SrCl₂ (0.5 M)	DI		—	7.5	—	14.5	—	1.9
4		65.3 (97.3)	CsCl (1 M)	DI		—	—	4.0	9.0	—	2.3
5		65.6 (97.0)	KCl (1 M)	K₂SO₄ (0.5 M)		—	—	—	34.0	16.5	2.1
6		67.2 (98.7)	KCl (1 M)	SrCl₂ (0.5 M)		15.5	8.0	—	—	—	1.9
7		64.9 (98.4)	CsCl (1 M)	KCl (1 M)		15.0	—	8.0	—	—	1.9
8		64.9 (98.4)	CsCl (1 M)	SrCl₂ (0.5 M)		—	14.0	7.0	—	—	2.0
9	K-Kaolin	62.0 (99.2)	CsCl (1 M)	DI	48	—	—	4.0	4.0	—	1.0
10	Washed Na-bentonite	64.2 (99.0)	CsCl (1 M), Na₂SO₄ (0.175 M)	Na₂SO₄ (0.175 M)	1,008	—	—	5.5	25.0	—	4.5
11		62.0 (99.8)	CsCl (1 M), Na₂SO₄ (0.25 M)	Na₂SO₄ (0.25 M)	1,281	—	—	5.5	45.0	—	8.2
12		64.9 (96.7)	Cs₂SO₄ (0.5 M), NaCl (0.25 M)	NaCl (0.25 M)	950	—	—	5.5	—	18.0	3.3
13		61.8 (99.6)	Cs₂SO₄ (0.5 M), NaCl (0.5 M)	NaCl (0.5 M)	1,247	—	—	5.0	—	25.0	5.0
14		59.8 (98.9)	CsCl (1 M), NaCl (0.5 M)	NaCl (0.5 M)	1,247	—	—	5.0	45.0	—	9.0

DI , paste prepared with deionized water.

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