Evaluation of some intercalation methods of dimethylsulphoxide onto HCl-treated and untreated Egyptian kaolinite

Abstract

Dimethylsulphoxide (DMSO)-kaolinite interlayer complexes are important precursors for the organo-modifications of kaolinite. DMSO intercalation into HCl activated (HK) and untreated (UnK) Egyptian kaolinites via four different techniques; reflux of DMSO/water mixture at 70°C (R1), ball-milling with DMSO followed by reflux at 140°C (R2) as well as room temperature ageing for two months in absence and in presence of water (2m and 2mW) were performed and compared. The complexes were investigated by IR spectroscopy, thermogravimetric analysis (TGA), X-ray diffractometry (XRD), mass spectroscopy (MS), elemental analysis, scanning electron microscopy – energy dispersive x-ray spectroscopy (SEM-EDX), and transmission electron microscopy (TEM). Fourier transform infra-red (FTIR) spectra showed a blue-shift in OH vibrations of the modified kaolinite due to the hydrogen bonds formed between DMSO molecules and the inner-surface hydroxyls of kaolinite with the order 2mW>2m>R2>R1 of DMSO loading. In addition, XRD, TGA and elemental analysis supported the same conclusion by high degree. HCl-treatment of clay was shown to reduce the intercalation of DMSO probably due to the reduction in its Al percentage. DMSO was suggested to be loaded onto kaolinite mainly via two mechanisms; intercalation and adsorption processes. The 2mW and 2m methods were recommended for higher adsorption and intercalation efficiencies of DMSO onto kaolinite.