The Study On Regeneration Of Phenol-satured Activated Carbon By Using Microwave Irradiation

Focused on the microwave regeneration of activated carbon, this paper started from analyzing the feasibility of microwave regeneration of activated carbon by three different means: GACM,GACN2-M and GAC_CO2-M,then discussed successively the influential factors and the optimum regeneration conditions of the GACN2-M and GAC_CO2-M, and the effect of the repeated microwave regenerations of activated carbon, and finally analyzed the mechanism of the microwave regeneration of activated carbon with a series of advanced analyzing and testing methods and thus provided a reference and basis for the process of microwave regeneration of activated carbon.According to the results of the research, GACN2-M is much more effective than GACM ,which is not very effective. GACN2-M, however,recommended in this paper, is proved to be better than GAC_CO2-M. The greatest influential factors for microwave regeneration of activated carbon are the microwave power and the time of irradiation, followed by the amount of activated carbon and the flow of the carring air. The content of water has little impact on the results, so the satured and wet activated carbon can be directly regenerated without drying before the irradiation of microwave, which simplifies the process of microwave regeneration of activated carbon. The cost of regenerating activated carbon with GACN2-M is 2.1 times of that with GAC_CO2-M, however ,the repeat regeneration effect of activated carbon with GACN2-M is obviously better than that of GAC_CO2-M,so it is the right way to regenerate activated carbon with GACN2-M in repeat regenerations of activated carbon in pactical process.The picture of scanning electron microscopy (SEM),the analysis of EDX surface elements and the results of BET surface area of activated carbon showed that, after microwave irradiation by the means of GACN2-M,the surface of activated carbon became rough with clear cracks and many blocked holes were opened and deepened, the average pore size of activated carbon increased and a certain proportion of middle sized pore contributed to the adsorption amount of phenol by the activated carbon. While through the microwave irradiation of GAC_CO2-M, there weren't a number of porous structure in the activated carbon and the carbon content suffered serious losses, the number of pores decreased as well as the surface area, thus the reduction in the adsorption of phenol. In the case of GACN2-M, the content of element C increased slightly while the element O decreased, but the case of GAC_CO2-M showed exactly the opposite result.The results of Boehm and PZC showed that after microwave irradiation, the acidic groups on the surface of the activated carbon decreased and the alkaline groups increased, which contributed to the adsorption of the phenol characterized by the hydrophobic property and weak acidcity. The results of GC/MS analyzer indicated that during the process of microwave radiation of activated carbon, the decomposition of phenol produced lots of products among which dibenzofuran, naphthalene and diphenyl ether; under conditions of nitrogen flow rate 0.1m3/h, microwave power 700W, irradiation time 30min, and after the first regeneration, the volatilization of phenol representd 48.64% of its total absorption, while the pyrolytic, oxidized and carbonized phenol accounted for 51.36%. There was no phenol left on the surface of activated carbon after the regeneration, which proves that the microwave regeneration of activated carbon is not only an effective way to regenerate activated carbon but also a good way to remove the organic pollutants.