Research On The Preparation Of Activated Carbon By The Method Of Physical Chemistry

It is well-known that as a kind of fine adsorbent, activated carbon can be applied in various fields and has been used rather abroad, and its demand manifolds increasingly. Then these years, the investigations and the trend of development about preparing activated carbon have became rather actively.We chosed the fast growing wood, such as, kenaf, Chinese fir, bamboo as the activated carbon precursors. The precursors, which include the precursors without adding impregnations and the counterpart added impregnations respectively, were analyzed the process of pyrolysis by thermogravimetric instrument. Then the weight diversifications on different precursors was gotten during the process of pyrolysis and the effective activing period of different precursors under the impregnation of phosphoric acid, the effective activation period of kenaf and Chinese fir is mainly 800℃-900℃, and the bamboo chips is mainly 850℃-950℃.Then we adopted the method of physical chemistry activation, under the suitable high temperature, imprenated with low concentration of phosphoric acid, analyzing the the relationship between the concentration of impregnations on the activation, indicating the degree of etching dued to different concentration of impregnations and various precursos, and the two factors of activated temperature and holding time were discussed, on the mechanism of preparing activated carbon. The results showed that, when the mass fraction of phosphoric acid was 3% or 5%, the adsorption value of methylene blue on activated carbon prepared from kenaf can reach 290ml/g, and its iodine value can be as high as 900 mg/g; when the mass fraction of phosphoric acid was 1%, the activated temperature was 900℃, holding time was 2 hours, the adsorption value of methylene blue and iodine value of activated carbon prepared from Chinese fir reached as high as 297ml/g and 989 mg/g.This paper carried out the research on the preparation of activated carbon under the impregnation of phosphoric acid and sulfuric acid in same concentration, probing into the factors of the concentrations of impregnation, activated temperature and holding time on affecting the adsorption property of activated carbon prepared. We went deep to character and analyze the structure and the surface configuration of activated carbon by technologies, i.e. Surface area and Pore Analyzer, Scanning Electron Microscope, Fourier Infrared Spectrograph and so on. The characterization results indicated that: in the range of low concentration impregnation, when the activated temperature is high enough and the holding time met the requirements, activated carbon with high specific surface area and large pore volume can be prepared, and along with the increasing of activated temperature and the extending of holding time, the carbon-net structure of the carbonization recombined constantly, the settled content of the carbon became more and more, then the degree of graphitization enhanced.It summed that the high-perfromance of activated carbon can be prepared from the impregnation of low concentration of phosphoric acid or mixed aid, bcecause the low concentration of impregnation we used, it's easy to deal with the process, and it isn't liable to bring in the pollution of environment, also it tend to eroding the instruments with little possibility, it did possess the practical signification in the production of industrialisaion.