埃洛石
高岭石
水溶液
化学工程
沉积作用
热重分析
蔗糖
化学
材料科学
矿物学
复合材料
地质学
有机化学
沉积物
工程类
古生物学
作者
Martina Maria Calvino,Giuseppe Cavallaro,Lorenzo Lisuzzo,Stefana Milioto,Giuseppe Lazzara
标识
DOI:10.1016/j.colsurfa.2022.128530
摘要
In this work, we propose an easy strategy for the separation of halloysite/kaolinite mixtures in sucrose aqueous solution. Preliminarily, we investigated the influence of the sucrose addition on the colloidal stability of kaolinite nanoplates and halloysite nanotubes (HNTs) dispersed in water. Dynamic Light Scattering (DLS) measurements revealed that the HNTs aqueous mobility is dependent on the sucrose concentration, while the ζ-potential is negligibly affected by the addition of the carbohydrate in the aqueous solvent. On the other hand, any variations on the surface charge and dynamic behavior of kaolinite were detected in the presence of sucrose. The obtained ζ-potential and DLS results were useful to interpret the sedimentation kinetics of kaolinite and halloysite dispersions. In particular, the peculiar sedimentation behavior of halloysite were discussed by considering the screening effect of sucrose on the attractive interactions between the nanotubes. The latter was evaluated by the calculation of the corresponding Hamaker constants. On this basis, we estimated that the optimization of the separation between kaolinite and halloysite might be achieved in 10 wt% sucrose aqueous solution. This hypothesis was confirmed by the separation experiments, which exploited the different sedimentation behavior of halloysite and kaolinite. Thermogravimetric experiments on the separated material and kaolinite/halloysite composites with variable composition allowed us to determine the efficiency of the separation protocol. To this purpose, the differential thermogravimetric curves were accurately analysed by using split Gaussian functions. In conclusion, this paper represents a further step in the purification of natural halloysite samples exploiting the ability of sucrose to control the attractive forces of the clay nanotubes as well as the colloidal stability of kaolinite nanoplates in aqueous solvent.
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