Synthesis Of Coal-bearing Kaolin-based Adsorbents And Their Properties

The calcination of coal-bearing kaolin at high temperature can alter its crystal structure and will lead to the formation of metakaolin with improved reactivities. When the metakaolin is treated by an acid or alkaline, it exhibits good pore structure distribution and surface properties; and hence, can be. used as a good support material. In this study, calcined coal-bearing kaolin was activated with hydrochloric acid treatments, and the morphological and structural properties of the treated material were characterized by thermogravimetry analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscope (SEM) and N2adsorption-desorption. The adsorption abilities of the activated coal-bearing kaolin for methylene blue as well as its regeneration methods also has been investigated. Furthermore, several kinds of activated coal-bearing kaolin-based composites were synthesized and their adsorption properties were studied in view of application to water treatment as summarized as follows:(1) Magnetic γ-Fe2O3/activated coal-bearing kaolin composite was prepared using CO(NH2)2and Fe(NO3)3·9H2O as raw materials and activated coal-bearing kaolin as support material, and it was characterized using XRD、N2adsorption-desorption and VSM. At the same time, the adsorption capacity of the magnetic composite for methylene blue was also investigated. The specific surface area and the saturation magnetization of the composite are measured to be68.8m2/g and26.6emu/g, respectively. The maximum adsorption capacity for methylene blue is as large as27.0mg/g.(2) Mesoporous TiO2/activated coal-bearing kaolin composite was synthesized by hydrothermal method and it was characterized by XRD and N2adsorption-desorption measurements. Furthermore, the adsorption abilities of the composite for Congo red have also been studied. The results show that the synthesized mesoporous TiO2/activated coal-bearing kaolin composite possesses a mesoporous structure with a BET surface area of258.9m2/g. The maximum adsorption capacity of the material for Congo red is estimated to be117.6mg/g.(3) The mesoporous magnetic TiO2/γ-Fe2O3-activated coal-bearing kaolin was prepared by hydrothermal method using the Ti(SO4)2as the titanium source and its adsorption abilities for Congo red was also investigated. VSM measurements show that the mesoporous TiO2/γ-Fe2O3-activated coal-bearing kaolin composite has a saturation magnetization of12.7emu/g. N2adsorption-desorption measurements exhibit the formation of mesoporous structure with an average pore size of3.49nm and a BET surface area of125.1m2/g. The maximum adsorption capacity of the composite for Congo red is as large as78.13mg/g.