Study On Principles Of Magnetization And Pore Size Regulation Of Coal-Based Activated Carbon

Pore size regulation plays an important role in the directional preparation of activated carbon, while magnetization of activated carbon is an effective approach to separating and recovering the spent activated carbon. In this paper, a simple one-step synthetic method was presented and studied for preparing magnetic activated carbon with regulated pore size from coal in the presence of transition metal compounds. The pore structure, surface morphology, microcrystalline structure, surface chemistry, magnetic properties and adsorption performances were characterized by N2 adsorption, SEM, XRD, FT-IR, TGA and VSM, iodine value and methylene blue value, respectively. The results show that Fe, Fe3O4 and Ni with strong magnetism transforme by iron-based and nickel-based additives during carbonization and activation process provided magnetism for activated carbon. In carbonization process, pyrolysis is intensified by addition of transition metal compounds, which hinderes the condensation of free radicals in the colloid formation stage, decreases the ordering extent of basic structural unit and degree of graphitization. It is beneficial to form amorphous structure in order to lay a foundation for pore-making and regulation in activation process. Beside, iron and nickel based additive could catalyze activation process and promote the formation of mesopores while has minor effect on microspores. Finally, Fe3O4 is screened out to be the best magnetic additive. With an addition of 6.0% Fe3O4, at carbonization temperature of 600℃and activation temperature of 880℃,the specific surface area and the specific saturation magnetization of derived coal-based magnetic activated carbon are 993.56m2·g-1,2.4158emu·g-1, respectively. When the amount of Fe3O4 varies, the ratio of micropores and mesopores in activated carbons can be easily regulated.