An Investigation of the Swelling Kinetics of Bentonite Systems Using Particle Size Analysis

Figures & data

Table 1. EDX analysis for raw, purified and activated bentonite

Element Commercial Raw Wet Sieved Thermochemically Bentonite Ca-Bentonite Bentonite Treated Bentonite
O	58.5	50.26	52.88	52.82
Na	1.39	1.73	1.77	6.6
Mg	0.9	1.46	1.36	1.42
Al	6.8	9.59	9.49	8.6
Si	28.9	25.1	25.31	22.91
Cl	–	1.22	1.6	2.83
K	0.19	0.54	0.59	0.31
Ca	0.48	0.91	0.89	0.4
Ti		0.83	0.89	0.41
Fe	2.69	6.64	3.83	3.57
Cu	–	0.74	0.57	0.13
Zn	–	0.88	–	–
S	0.15	–	–	–
Na/Ca ratio	2.896	1.91	1.98	16.5

Figure 1. Bentonite recovery from wet and dry sieving.

Figure 2. Effect of purification of raw bentonite on the PSD compared to commercial bentonite.

Figure 3. Effect of the Na₂CO₃ treatment on swelling using PSD.

Table 2. Impact of Na2CO3 addition at room temperature on PSD analysis after 24 hrs.

Na2CO3 wt.%	[A]	[A]/[A]o	1/[A]	Dn	Dw	Dz	DI
0%	49.46	1.00	0.02	4.97	9.06	13.38	1.82
2%	27.86	0.56	0.04	2.80	4.62	6.69	1.65
4%	13.92	0.28	0.07	3.31	5.24	7.53	1.58
8%	13.86	0.28	0.07	3.31	5.24	7.53	1.58
12%	12.76	0.26	0.08	3.08	4.48	5.73	1.45

Figure 4. The effect of Na₂CO₃ treatment on swelling and rheology.

Figure 5. Effect of combined heating and stirring on PSD of Ca-bentonite and Na-bentonite.

Figure 6. Effect of the thermochemical treatment on the swelling of bentonite using PSD.

Table 3. Impact of 4 wt.% Na2CO3 on PSD analysis

Treatment @ 25oC
Time (hrs.)	[A]		[A]/[A]o	1/[A]			Dn	Dw		Dz		DI
0	49.46		1	0.0202			4.9691	9.05743		13.378		1.8228
6	29.11		0.588	0.0344			4.98629	9.42386		14.272		1.89
12	22.1		0.447	0.0452			3.58815	6.06085		10.295		1.6891
24	11.3		0.228	0.0885			1.33359	2.16406		2.8693		1.6227
Treatment @ 45oC
Time (Hrs.)	[A]		[A]/[A]o	1/[A]			Dn	Dw		Dz		DI
0	49.46		1	0.0202			4.9691	9.05743		13.378		1.8228
1	10.84		0.219	0.0923			1.08873	1.78331		2.5199		1.638
3	5.602		0.113	0.1785			0.92261	1.67201		2.6943		1.8123
6	3.422		0.069	0.2922			0.54863	0.69374		0.8486		1.2645
12	2.568		0.052	0.3894			0.81264	0.96998		1.133		1.1936
24	0.912		0.018	1.0968			0.56282	0.5952		0.6284		1.0575
Treatment @ 65oC
Time (Hrs.)		[A]	[A]/[A]o		1/[A]	Dn			Dw		Dz		DI
0		49.46	1		0.020	4.969			9.057		13.378		1.823
1		10.28	0.207		0.097	5.360			6.523		11.633		2.048
3		2.10	0.0424		0.477	2.999			4.592		5.833		1.531
6		1.47	0.029		0.679	1.078			1.405		1.615		1.302
12		0.53	0.010		1.901	0.818			1.089		1.198		1.332
24		0.35	0.007		2.825	0.839			1.101		1.199		1.313

Figure 7. Effect of the heating time on swelling using particles size D₁₀, D₅₀, and D₉₀, and rheology of thermally treated Na-bentonite.

Figure 8. A plot of 1/[A] vs. time for thermally treated Na-bentonite at 25 °C, 45 °C, and 65 °C.

Table 4. Temperature dependence and reaction energy calculation

Temp., ^oC	Temp., K	k, hr^−1	1/T, K^−1	ln k
25	298.15	0.002	0.00335	−6.21461
45	318.15	0.042	0.00314	−3.17009
65	338.15	0.124	0.00296	−2.08747

Figure 9. A plot of ln k vs. 1/T, K⁻¹ for thermally treated Na-bentonite.