Effect of Soil Solution pH during the Tetracycline Intercalation on the Structural Properties of a Dioctahedral Smectite: Microstructural Analysis

Table 3

Structural parameters used to reproduce experimental XRD patterns as a function of soil solution pH and %RH.

pH	%RH	%MLS	1W/2W/3W/4W^†	//	Physical mixture	1W/2W/3W/4W
3	20	13	00/00/89/11	0.30//0.30	R0	09.70/11.10/12.60/14.10	4
		38	60/35/05/00	0.28//0.28	R0
		49	18/00/82/00	0.50//0.50	R0
	40	15	70/00/30/00	0.31//0.31	R0	09.70/11.10/12.60/14.10	4
		25	14/06/80/00	0.41//0.41	R0
		60	20/00/75/05	0.37//0.37	R0
	60	45	00/16/84/00	0.87//0.87	R0	09.70/11.10/12.60/14.10	5
		55	11/00/85/04	0.54//0.54	R0
	80	41	00/09/91/00	0.38//0.38	R0	09.70/11.10/12.60/–	4
		59	04/06/90/00	0.27//0.27	R0
4	20	17	00/00/88/12	0.50//0.30	R1	09.70/11.10/12.60/14.10	5
		33	00/04/79/17	0.55//0.29	R1
		50	10/15/75/00	0.64//0.34	R1
	40	13	00/00/90/10	0.47//0.21	R1	09.70/11.10/12.60/14.10	6
		22	00/00/100/00	—	—
		65	18/04/78/00	0.81//0.34	R1
	60	16	40/12/48/00	0.64//0.29	R1	09.70/11.10/12.60/–	5
		42	33/16/51/00	0.67//0.35	R1
		42	40/00/60/00	0.52//0.31	R1
	80	26	00/00/77/23	0.81//0.20	R1	09.70/11.10/12.60/14.10	4
		29	40/35/15/10	0.80//0.30	R1
		45	38/12/42/08	0.72//0.38	R1
5	20	35	00/33/55/12	0.55//0.35	R1	–/11.10/12.60/14.10	4
		28	00/45/50/05	0.81//0.54	R1
		37	00/32/39/29	0.64//0.35	R1
	40	26	00/05/60/35	0.78//0.27	R1	–/11.10/12.60/14.10	5
		14	00/00/38/62	0.78//0.34	R1
		60	00/09/50/41	0.56//0.24	R1
	60	12	00/19/72/09	0.49//0.18	R1	–/11.10/12.60/14.10	4
		27	00/50/25/25	0.35//0.12	R1
		40	00/24/38/38	0.48//0.28	R1
		21	00/00/50/50	0.51//0.37	R1
	80	30	00/20/80/00	0.71//0.54	R1	–/11.10/12.60/14.10	4
		19	00/10/60/30	0.77//0.48	R1
		51	00/10/55/35	0.64//0.23	R1
6	20	22	00/17/83/00	0.81//0.35	R1	–/11.10/12.60/14.10	4
		78	00/05/85/10	0.79//0.25	R1
	40	27	00/00/80/20	0.55//0.30	R1	–/11.10/12.60/14.10	4
		73	00/09/60/31	0.74//0.35	R1
	60	15	00/15/45/40	0.78//0.23	R1	–/11.10/12.60/14.10	5
		25	00/10/90/00	0.65//0.38	R1
		60	00/08/87/05	0.84//0.40	R1
	80	45	00/00/35/65	0.72//0.30	R1	–/11.10/12.60/14.10	4
		55	00/20/50/30	0.60//0.30	R1
7	20	20	00/44/52/04	0.55//0.30	R1	–/11.10/12.60/14.10	4
		70	00/45/55/00	0.50//0.34	R1
		10	00/45/45/10	0.77//0.41	R1
	40	28	00/55/45/00	0.80//0.20	R1	–/11.10/12.60/14.10	3
		72	00/35/57/08	0.76//0.25	R1
	60	35	00/48/48/04	0.55//0.22	R1	–/11.10/12.60/14.10	5
		65	00/68/32/00	0.50//0.38	R1
	80	38	00/50/50/00	0.55//0.18	R1	–/11.10/12.60/14.10	4
		62	00/65/30/05	0.80//0.26	R1
8	20	25	00/55/45/00	0.71//0.21	R1	–/11.10/12.60/14.10	6
		35	00/40/10/50	0.64//0.28	R1
		40	00/48/12/40	0.55//0.24	R1
	40	35	00/42/18/40	0.49//0.30	R1	–/11.10/12.60/14.10	5
		35	00/50/00/50	0.62//0.15	R1
		30	00/55/00/45	0.81//0.30	R1
	60	25	00/49/40/11	0.50//0.30	R1	–/11.10/12.60/14.10	4
		28	00/55/45/00	0.54//0.33	R1
		47	00/45/43/12	0.64//0.18	R1
	80	42	00/40/60/00	0.66//0.30	R1	–/11.10/12.60/14.10	4
		20	00/46/50/04	0.50//0.27	R1
		38	00/55/45/00	0.55//0.16	R1

Note: 4W, 3W, 2W, and 1W are attributed to the layer hydration state. R0 and R1 describe mixed-layer structures with random interstratifications or with partial segregation, respectively. indicates homogenous structure. is the junction probability of layer type j to follow layer type i, and abundances of layer type i. In this case, i is Na and j is TC, wherein four equations are used: (1), (2), (3), and (4). : position of exchangeable cations per half unit cell calculated along the axis. : average position of the adsorbed TC molecule is fixed at 15.40 Å. : average layer number per stacking.