Abstract: Adsorption of organic matters on clay minerals is a ubiquitous phenomenon. In order to better understand such a
reaction, adsorption behavior of lysine onto clay minerals including saponite, montmorillonite, kaolinite, chlorite and illite was
investigated and characterized by powder X-ray (XRD), Fourier-transform Infrared Spectroscopy (FTIR) and Thermal Gravimetric
Analysis (TGA). The results showed that the adsorption isotherms of lysine on clays were well fitted using the Freundlich equation
(R2=0.98-0.83) and the adsorption capacity followed the order: saponite>montmorillonite>chlorite>kaolinite>illite. XRD results
indicated that the adsorption of lysine on saponite and montmorillonite ocurred mainly in the interlayer regions, while lysine was
mainly present on the surface of chlorite, kaolinite and illite. Furthermore, FTIR and TG results showed adsorption of lysine in the
interlay region might take place via replacement of interlayer water and subsequent formation of hydrogen bond with O-Si-Si(IVAl).
This work will contribute to understanding of adsorption behavior and mechanisms of organic matters on clay minerals.

Key words: saponite, kaolinite, chlorite, illite, lysine, adsorption