Intercalation of a block co-polymer in kaolinite

Effect of Unhydrated Aminopropyl Triethoxysilane Modification on the Properties of Calcined Kaolin

Unhydrated aminopropyl triethoxysilane was used to modify calcined kaolin produced from coal-bearing kaolinite. The aim was to develop a simple and economic modification method without the need for solution immersion and subsequent wastewater treatment. The samples before and after modification were tested using multiple methods, such as XRD, MAS-NMR, FT-IR, XPS, and SEM. The study results indicate that this modification can effectively improve the surface property of calcined kaolin. The activity index increased to 76.7% when the modifier usage was 2%. With a further increase in the modifier content, the activity index decreased. Surface modification did not reduce the whiteness of calcined kaolin. Further, the modification reaction mechanism was elucidated. Based on the detailed analyses, it was found that the modification reaction took place between the NH2 groups in the modifier molecules and AlVI-OH in calcined kaolin, and hydrogen bonds were formed between the NH2 groups and the active sites on the calcined kaolin surface.

Characterization and Applications of Kaolinite Robustly Grafted by an Ionic Liquid with Naphthyl Functionality

Functionalization of the kaolinite (K) interlayer space is challenging. In this work, a new kaolinite-based nanohybridmaterial (K-NI) was successfully synthesized by grafting on the interlayer aluminol surfaces the ionic liquid, 1-(1-methylnaphthyl)-3-(2-hydroxyethyl) imidazolium chloride (NI), using a guest displacement strategy. A substantial increase of the basal spacing (10.8 Å) was obtained. This is a grafted derivative of kaolinite possessing one of the largest d-values. Washing in water for several days and other vigorous treatments such as sonication showed a minor effect on the integrity of the material. FTIR and ¹³C NMR confirmed the conservation of the structure of the ionic liquid after the grafting. Thermal analysis confirmed the presence of grafted material and was used to estimate the abundance of the grafted ionic liquid (0.44 mole per mole of kaolinite structural formula, (Al₂Si₂O₅(OH)₄)). By using cyclic voltammetry, the permeability of a film of K-NI for the bulky ferricyanide ions was demonstrated. The accumulation of nitrophenolate anions was effective (maximum capacity of 190 μmol/g), but was less important than what was expected due to the steric hindrance of the bulky grafted NI. Although the presence of chloride anions reduced the adsorption capacity, the affinity of the modified kaolinite interlayer space for the nitrophenolate anions was demonstrated.