Characterization of South African Bentonite and Kaolin Clays

Abstract

The present study aimed to investigate the mineralogical and morphological properties of two South African clays, namely bentonite and kaolin. These clays are mined in specific regions of the country but have not been fully characterized in terms of their properties for potential application in a number of industries. Bentonite was found to have a larger specific surface area, pore size, and more interchangeable cations than kaolin. The bentonite was also identified as Na-bentonite due to the huge Na content present in the clay. The powder X-ray diffraction (PXRD) patterns revealed that both clays are crystalline, together with the Fourier-transform infrared (FTIR) spectrophotometer results; presumably, some impurities of quartz could be present in the clay materials. The most prevalent functional groups present include Al-OH, Si-O-Mg, Si-O, and Si-O-Al groups. The surface charge of bentonite was consistently negative across all pH values, indicating its potential for adsorption applications. On the other hand, kaolin exhibited a negative charge at pH values greater than 2.4. The scanning electron microscopy (SEM) images provided visual evidence of the presence of pores in the clay structures, which supported the Brunauer–Emmett–Teller (BET) results classifying both bentonite and kaolin as mesoporous and macroporous materials. The particle size analysis revealed a broad distribution for bentonite and a bimodal distribution for kaolin. Overall, the clays revealed interesting features that can be useful for application in several industries, for example, in the treatment of wastewater. Further research and development can explore their potential to address environmental challenges, particularly the application of bentonite and kaolin in water treatment processes to remove toxic metal ions.

Characterization of the Mechanical, Biodegradation, and Morphological Properties of NBR/Biopolymer Blend, Integrated with a Risk Evaluation

“…However, a notable disparity was observed in the initial stages of decomposition, where pure NBR began to degrade at approximately 321 °C associated with 5% weight loss, while the NGP-blended NBR exhibited an earlier onset of degradation at 229 °C. This divergence suggests that the NGP-blended sample may undergo the decomposition of Bentonite and iron oxide at lower temperatures, attributed to the influence of NGP − …”

Green clay materials applied in packed bed columns for adsorption of hexavalent chromium from aqueous solutions

“…The limited absorption over a range of high P/P0 and capillary condensation occurring in mesopores are the causes of the observed hysteresis (Omer et al, 2018;Dinh et al, 2022). The IUPAC classification allows the hysteresis to be categorized as type H2 (Kgabi and Ambushe, 2023). Table 1 shows the properties of GCM.…”

Synthesis and Characterization of Nanocomposite Hydrogels Based on Poly(Sodium 4-Styrene Sulfonate) under Very-High Concentration Regimen of Clays (Bentonite and Kaolinite)

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