Preparation and characterization of soy lecithin-modified bentonites

Abstract

In this work, a study of exchange of soy lecithin, a natural product, in bentonite was performed in order to synthesize bio-organoclays. The effects of initial amount of modifier and reaction time were studied at a fixed reactiontemperature. Organoclays thus obtainedwere characterized by means of X-ray diffraction (XRD) analysis, Xray fluorescence spectrometry (XRF), thermogravimetric analysis (TGA), Fourier transforminfrared spectroscopy (FTIR) and water absorption tests. An effective intercalation of soy lecithin between the clay layerswas obtained.The ionic exchange reaction was completed at short times whereas variations in the initial amount of modifier produced organoclayswith different final properties. At lowratios of soy lecithin to bentonite, a slight increment in basal spacing of organoclays was observed due to intercalation of the organic modifier between the clay layers and a significant diminution on water absorption was achieved. When the organic content increased, the interlayer spacing increased but thermal stability of organoclays decreased compared to the sampleswith loworganic content, whereas the water absorption was not affected. The obtained bio-organoclays are potential environmental-friendly fillers for the development of clay/biopolymer nanocomposites.