Study On Preparation And Properties Of Magnetic Coal-based Activated Carbon

Ningxia anthracite is abundant in China,with high carbon content and excellent comprehensive performance.It is commonly used as energy material and coal chemical products,which has serious environmental pollution.With the development of new energy and the state’s demand for ecological environment,the development of coal industry has been gradually restricted.In recent years,the state has endeavored to seek new directions for coal utilization and put forward guidelines for clean coal technology.So ningxia anthracite was chosen as raw material,to explore the influence factors of preparation and adsorption performance of coal based activated carbon.The major works and results are summarized as follows:Ningxia anthracite coal is selected as the raw material of coal based activated carbon because of its high metamorphism degree,low ash content and high fixed carbon content,which is conducive to the formation of pore structure of activated carbon.In coking stage,best raw coal particle size in 0.2~0.3mm,the raw coal particle size is too small lead to carbonized material microporous,low yield,and is not conducive to recycling,too much raw coal particle size is smaller than the surface,hole under unit quality small volume;Best heating rate of 5 ℃ / min,the higher the heating rate,production rate is low,not only and is not conducive to generate stable carbon skeleton;Best carbonization temperature is 550℃ heat preservation 2 h,carbonization temperature makes the graphitization of carbon tend to be more orderly and conducive to the formation of pore structure.In the activation stage,KOH was selected as an activator,infiltrated raw coal and activate in tube furnace.Firstly,the main influencing factors was found by the orthogonal experiment and the best optimal scheme: a preliminary base carbon ratio of 2:1,alkali solution concentration is 0.2g/ml,alkali leaching time is 8h,activation temperature is 750℃.Then,the main influencing factors were analyzed by single factor experiment.With the increase of alkali carbon ratio and concentration of KOH,the specific surface area and pore volume of activated carbon were gradually increased,but the amplitude gradually decreased.The coal-based activated carbon of the best optimal scheme has maximum specific surface area: 1356 m2/g.From the dynamic point of view,the coal based activated carbon is more consistent with the pseudo second-order kinetic adsorption process.From the analysis of isothermal adsorption curve,it is closer to the multi-layer adsorption model of Freundlich.Ferrocene is used as activator and load agent to prepare magnetic coal based activated carbon.On the one hand,the ferrocene promote the formation of the pore structure;on the other hand,coal based activated carbon is loaded with magnetic Fe3O4,reuse cycle,improve their practical value.First of all,the optimal scheme is determined by the orthogonal experiment: the mixing time is 30 min,activation temperature is 1000 ℃,iron carbon ratio is 2:1,and activation time is 2h.Then the main influencing factors were analyzed by single factor experiment.With the increase of the proportion of ferrocene,the specific surface area of the magnetic coal base activated carbon decreases with the increase of the surface area,and the magnetic energy increases continuously,while the absorbing performance decreases gradually and moves to the low frequency.The magnetic coal-based activated carbon of the best optimal scheme has maximum specific surface area: 1356 m2/g and the saturation magnetization intensity: 16.46 emu·g – 1.Otherwise,the magnetic coal-based activated carbon is separated from liquid in the 20 s and has high recovery efficiency.The adsorption of magnetic coal based activated carbon to methylene blue is more consistent with the pseudo-second-order kinetic adsorption process,which is mainly dominated by chemical adsorption,which conforms to the Langmuir single-layer adsorption model.