Research On The Preparation, Molding And Activation Mechanism Of Biomass Activated Carbon

Activated carbon (AC) is a high adsorption capacity carbon material with abundant pore structures and developed specific surface areas which is widely used for liquid and gas purification, solvent recovery, as well as catalyst support. And its demand is increasing year by year. As the traditional raw materials for AC production are almost coal, it has become an inevitable choice that using the wastes from agriculture and forestry as the raw materials for activated carbon production.The objective of this thesis is to investigate the feasibility that biomass wastes substitute lignite to produce activated carbon and at the same time obtain high quality activated carbon from biomass wastes. Furthermore, the reasons for different activation characteristics and activated carbon performance from different raw materials were detected, which will provide a theoretical direction and technical support for activated carbon raw material selection in industrial. The following summarizes the major research contents and results:(1) In this work, systematic experimental studies on activated carbon preparation in the lab through steam activation were performed by using lignite as the basic raw material. The experimental conditions of activation such as activation temperature and activator amount were optimized. The results show that the optimal conditions are activation temperature of850℃, the amount of water vapor0.04g/min-g carbonized material. And under this condition, rice husk and sawdust were used as the raw materials to prepare activated carbon, respectively. The results show that under the same activation condition the activation activity of biomass feedstock is higher than lignite and the obtained activated carbons possess better iodine and methylene blue adsorption capacities.(2) For high-ash content raw material rice husk, alkali-deashing process can effectively improve its activation properties and then can produced excellent activated carbon in a short time. For the deashing filtrate, it can form colloidal precipitate by adjusting the pH. After filtering, washing and drying, high grade white carbon black was co-produced and achieving the full use of rice husks.(3) Through comparing the difference of activated carbon adsorption performance for which produced by different raw materials under the same carbonization and activation condition, the activation mechanism of different raw materials were analyzed. From the steam gasification activity, specific surface area, pore structure, FT-IR, XRD, and XPS analyses of raw materials and carbonized materials, we can preliminarily reveal the cause of the different activation characteristics for different raw materials.(4) In the activated carbon molding process, when CMC and aluminum sol were both used as binder, low dosage of adherent binder can make the molded activated carbon reach a satisfied strength. The adsorption ability and physical and chemical structure of the molded activated carbon have little change comparing with the raw powder activated carbon.