The Relationship between Structural Variation and Relevant Properties of Palygorskite in Activation Process

The activated palygorskite has been widely used as sorption agent. Normally, there are two activating methods including the acid activating and the heat activating. The crystal structural variations of fibrous and earthy palygorskite, which were activated by HCl and heat, have been studied in this paper by using X-ray diffraction (XRD) and infrared spectrometry (FT-IR). The analyses show that no variation has occurred for the structure of the HCl activated fibrous palygorskite in comparison with that of the original fibrous palygorskite. However, the structure of the HCl activated earthy palygorskite is different to that of the original earthy palygorskite. For the earthy palygorskite activated by 1. 0mol/L HCl acid, a part of positive ions coordinated in its octahedron would be substituted by H+ or be dissolved out, and thus resulted in the decrease of its cell parameter. For the earthy palygorskile activated by 1. 5mol/L HCl acid, its octahedron sheet would be collapsed, its SiO2 would be extricated, and its crystal structure would be destructed obviously. Therefore, the increase of acid concentration would not increase the activity of the palygorskite. For the earthy palygorskite activated by over 350℃ heating, its crystal structure would be obviously damaged and its decolorized rate would be obviously decreased by the Fe2O3 derived from decomposition and oxidation of the earthy palygorskite.