Hybrid materials prepared by interlayer functionalization of kaolinite with pyridine-carboxylic acids

This paper presents the results of the functionalization of Brazilian São Simão kaolinite with pyridine-2-carboxylic and pyridine-2,6-dicarboxylic acids. The functionalization involved refluxing of the pyridine-carboxylic acid in the presence of kaolinite previously intercalated with dimethyl sulfoxide; both acids effectively displaced dimethyl sulfoxide from the clay interlayer. The resulting materials were characterized by X-ray diffraction, thermal analysis, infrared absorption spectroscopy, and C and N elemental analysis. The X-ray diffractograms revealed the incorporation of the acid molecules into the interlayer space of kaolinite. The thermogravimetric curves of the kaolinite samples functionalized with the pyridine-carboxylic acids indicated that the materials were thermally stable up to 300 °C. The displacements of the bands due to interlayer hydroxyls in the infrared absorption spectra also confirmed the functionalization of the kaolinite with the pyridine-carboxylic acids.

Graphical abstractKaolinite, previously intercalated with dimethylsulfoxide, has been successfully functionalized with picolinic acids (pyridine-2-carboxylic and pyridine-2,6-dicarboxylic acids).Figure optionsDownload full-size imageDownload as PowerPoint slide