EFFECT OF MONTMORILLONITE LAYER CHARGE ON THE THERMAL STABILITY OF BENTONITE

The thermal stability of bentonite is vitally important for its application in the casting field and the layer charge of montmorillonite (Q(m)) is one of its central crystal-chemical parameters. As the main component of bentonite, the influence of Q(m) on montmorillonite properties and behavior needs to be considered if bentonite is to be used in high-temperature environments. The objective of the current study was to investigate the relationship between Q(m) and the thermal stability of Chinese bentonite samples collected from Wuhu, Anhui Province (marked as WH); Xinyang, Henan Province (marked as XY); and Santai, Sichuan Province (marked as ST) below. The values of Q(m) were obtained using the O (11) method, and the structural properties of the bentonite samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetry-differential scanning calorimetry (TG-DSC), and field emission scanning electron microscopy (FESEM). The results showed that, in the samples investigated, Q(m) was inversely related to the thermal stability of bentonite. The Q(m) value (electrons per half unit cell, e/huc) was greatest for sample ST (0.725 e/huc), followed by sample XY (0.470 e/huc), and by sample WH (0.354 e/huc). The dehydroxylation temperature changed related to Q(m); the sample with the largest Q(m) value was WH (701 degrees C), followed by sample XY (684 degrees C), and sample ST (630 degrees C). After the samples were calcined at 600 degrees C, sample WH had the best montmorillonite structural integrity with the greatest degree of reusability (78.21%); while the montmorillonite structures of samples XY and ST were destroyed, and their reusabilities were only 9.48 and 6.01%, respectively.

Automated summary

The study suggests a negative correlation between the layer charge of montmorillonite (Q(m)) and the thermal stability of bentonite. The larger the Q(m) value, the lower the thermal stability of bentonite. Different Chinese bentonite samples from Wuhu, Xinyang, and Santai showed varying levels of Q(m) and thermal stability, with structural integrity and reusability being influenced by these factors.