Discretization of the Water Uptake Process of Na-Montmorillonite Undergoing Atmospheric Stress: XRD Modeling Approach

Table 1

Some structural parameters obtained from the quantitative XRD analysis in the case of the unstressed sample along the sorption process.

%RH	Layer stacking mode	M
4	R0	7
	—
	R0
7	R0	7
	—
	R0
10	R0	8
	—
	R0
13	R0	8
	—
	R1 (PAA = 0.80)
	R1 (PAA = 0.85)
16	R0	8
	—
	R1 (PAA = 0.85)
	R1 (PAA = 0.70)
19	R0	8
	—
	R1 (PAA = 0.85)
	R1 (PAA = 0.70)
22	R1 (PAA = 0.75)	8
	R1 (PAA = 0.70)
	R0
25	R1 (PAA = 0.75)	9
28	R1 (PAA = 0.75)	9
31	R1 (PAA = 0.75)	7
34	R1 (PAA = 0.70)	6
37	R1 (PAA = 0.70)	6
	R1 (PAA = 0.70)
40	R1 (PAA = 0.70)	5
43	R1 (PAA = 0.75)	5
46	R1 (PAA = 0.87)	5
	R1 (PAA = 0.70)
	R0
49	R1 (PAA = 0.87)	5
	R1 (PAA = 0.70)
	R0
52	R1 (PAA = 0.85)	5
	R1 (PAA = 0.96)
	R1 (PAA = 0.70)
	R1 (PAA = 0.70)
55	R1 (PAA = 0.70)	5
	R1 (PAA = 0.90)
	R0
58	R1 (PAA = 0.70)	6
	R1 (PAA = 0.90)
	R1 (PAA = 0.75)
61	R1 (PAA = 0.75)	6
	R1 (PAA = 0.88)
64	R1 (PAA = 0.75)	5
67	R1 (PAA = 0.80)	5
70	R1 (PAA = 0.85)	5
73	R1 (PAA = 0.85)	5
76	—	5
	R0
	R0
79	—	5
	R0
	R0
82	—	5
	R0
	R0
85	—	7
	R0
	R0
88	R0	7
	R0
	R0
91	R0	7
	R0
	R0
94	R0	6
	R0

Note: 3W, 2W, 1W, and 0W are attributed to the layer hydration state. : the number of H₂O molecules per half unit cell is fixed to 2.5, 5.6, and 6.1, respectively, for 1W, 2W, and 3W. Z_Na: the position of exchangeable cations per half unit cell calculated along the axis is fixed to 8.30 Å, 9.50 Å, 11.25 Å, and 12.60 Å, respectively, for 0W, 1W, 2W, and 3W hydration state. n_Na: the number of H₂O molecules per half unit cell is fixed to 0.33, indicating full saturation of the cation exchange capacity (CEC) of the minerals. R, Reichweite factor; R0 and R1 describe the MLS with random interstratifications or with partial segregation; M: the average number of layers per particle; P_AA: layer succession law.