| Carbon microsphere has become a hotspot in the catalyst carrier, lubricant, and wear-resisting materials fields for its advantages of high strength, high heat resistance, low density and other excellent characteristics. Carbon microsphere can effectively absorb heavy metals in wastewater and separate atmospheric pollutants with its special structure and rich surface oxygen functional groups. Thus, carbon microsphere has received the extensive concern of academia and industrial fields. Usually natural asphalt and polycyclic aromatic compounds are often the main raw materials of carbon microspheres, and sugar compound is used in recent years, but few people used biomass materials as raw materials in preparation carbon microspheres directly. Therefore, how to expand the carbon microsphere preparation of raw materials, as well as how optimize the preparation methods for producing a low production costs, efficient and fast green carbon microspheres and the further functionalization has great theoretical significance and potential application.This paper based on a large number of the researches in domestic and foreign as well as the progress of our research group in controlled preparation of carbon microspheres. The largest reserve of natural macromolecular compound in the nature was cellulose as raw materials, using environmental-friendly hydrothermal carbonization synthetic method, to prepare new material---carbon microsphere. Scanning electron microscopy, field emission electron microscopy, infrared spectroscopy, X-ray diffraction, photoelectron spectroscopy, UV-visible molecular absorption spectroscopy and N2absorption isotherm were used for the characterization of carbon microsphere. The particle size, morphology and chemical structure of carbon microsphere were characterized.Research of carbon microsphere and application were summarized. The research background, programs, contents, innovation point and the main method of this study were led to according to the research in this area.Well-dispersed micrometer-sized carbon spheres (CSs) were prepared by citric-acid-catalyzed hydrothermal carbonization of cellulose. The results showed that the shape and size of the obtained carbons were highly dependent on the concentration of catalyst, hydrothermal temperature and reaction time. The optimal citric acid concentration, hydrothermal temperature and reaction time for the synthesis of carbon with smooth and regular sphere morphology was2.5wt%,240℃and12h, respectively. The prepared carbon microspheres were exhibited spherical morphology and smooth surface between diameter of0.5μm and5μm. The formation of CSs from cellulose followed the paths of hydrolysis, dehydration, polymerization and aromatization. The obtained CSs consisted of aliphatic structures and rich oxygen-containing functional groups on the surface. When the concentration of the aqueous solution of AgNO3was0.08mol/L, Ag/CSc supported silver content of48.67wt%. The results indicated that existing of oxygen-containing functional groups effectively loaded silver ion by complexation. and it showed resistance to silver bleed properties.Flower type carbon microspheres (CSc) were prepared from cellulose using acrylic acid as acid catalyst and self-assemble by hydrothermal treatment. The morphology and diameter size of carbon microspheres could be controlled by the reaction hour, reaction temperature, and the concentration of acrylic acid. The results showed that the reaction temperature affected the morphology and dispersion of carbon spheres, the reaction time decided particle size of carbon sphere, and the amount of acrylic acid could change the smooth surface of carbon spheres to flower structure. The characterization showed that abundance of carboxylic group loaded on the surface of carbon microspheres and increased with increasing the dose of acrylic acid. The synthesized materials proved to be feasible for use in adsorption experiments for removal of heavy metals from aqueous solutions. The adsorption capacity was as high as165mg/g for Cu (Ⅱ). The parameter indicated the adsorption capacity of CSc was fitting the data to the Freundlich isothermSpherical carbon with smooth surface and micrometer-size (CSS) were prepared from cellulose in present of concentrated sulfuric acid by hydrothermal treatment. The effects of different reaction temperature, time and concentration of concentrated sulfuric acid on the performance of carbon microspheres were investigated. Finally, the morphology of carbon materials was sphere-like with the particle diameter of2-5μm. As the concentration of concentrated sulfuric acid was increased from1%to6%. the number of-SO3H surface functional group was increased from0.653mg/g to1.951mg/g. The results proved that CSS as solid acid showed that a much higher catalytic performance in the microwave reaction of hydrolysis cellulose. The total reducing sugar yield reached77.3%. and can be recover and reuse.Mesoporous carbon spheres (CSF) with tunable morphology and pore structure were prepared from cellulose via soft-template and the hydrothermal method. The diameter size of carbon spheres can be controlled by the concentration of F127. the morphology and the pore structure can be tunable by carbonization temperature. The results showed that the particle size decreased from2μm to200nm with increasing F127dosage from0.5g to1.5g. Pore size transformed were increased from2.92nm to3.62nm with the carbonization temperature. as well as the maximum surface area and pore volume were889.98m2/g and0.6087cm3/g. at the carbonization temperature of900℃. And there was barley functional group on the surface of carbon spheres. |
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