Study On Preparation Of SiO₂-lignin Composite Microspheres From Rice Husk Component And Its Adsorption Properties

In China, the huge population base makes the demand and yield of rice are very high. According to relevant statistics, India and Chinese accounted for half in the sum of world rice production. As the main by-product of rice production in the process of production, the output of rice husk is enormous. The rice husk is low value energy in traditional view, usually treated by direct burning or abandoned in farmland, which not only caused the biomass waste of resources, but also brings huge environmental pollution. Rice husk is mainly composed of cellulose, hemicellulose, lignin and silica and other components, therefore rice husk can be a precursor for preparing raw silicon or carbon-based material. This paper mainly introduces how to use the rice husk as raw material to prepare silica lignin composite microspheres, and the effects of lignin content in the microspheres of the adsorption properties, processing with different methods of composite microspheres to improve the content of organic components in microspheres. The adsorption properties of microspheres were investigated, compared the adsorption performance, get the best adsorption condition. Try to remove the silica in microspheres and carbide microspheres, observe the structure of residual lignin material and carbon material. Try to obtain the composite which was prepared by rice husk through a series of experiments, provides a new idea for rice husk recycling、turning waste into treasure.The main research work is as follow:1. Use the black liquor of rice husk following NaOH pretreatment,for the preparation of SiO2-lignin composite microspheres by sol-gel method. Using the hydrothermal method and cross-linking method to improve the content of organic components in the microspheres, Structure and morphology and organic content of microspheres were characterized by SEM, TEM and TGA,the content of lignin in microsphere were significantly improved by hydrothermal method,shell stability is also improved, hydrothermal method is simple and effective to improve the content of lignin in the composite microspheres.2. Composite microspheres with different lignin content was used in the test of the adsorption of silver nitrate, the increase improved of adsorption properties of silver nitrate was found in the microspheres, the adsorption quantity of microsphere without hydrothermal treatment was 21.7 mg/g, through the hydrothermal treatment adsorption capacity increased to 55.6 mg/g, what proved that hydrothermal treatment method is a simple and effective methods to enhance the adsorption quantity.3. The factors of the adsorption experiment and the optimum adsorption conditions was studied. The XRD and TEM results of the microspheres with adsorption of silver ions shows Ag have generated after adsorption on the surface of microspheres. A series of experiment makes it to be possible for rice husk, this waste can be used in the preparation of composite.4. Composite carbide before and after the treatment respectively using HF, try to remove the silica, and then observe change of its internal structure by using the transmission electron microscopy, thermogravimetric analysis the removal of silica.