Modification Research Of Mesoporous Activated Carbon For Adsorption Of PCDD/Fs

Incineration technique is an efficient method for municipal solid waste (MSW) treatment to China. It is reduction, recycling and harmless. However, the combustion of organic matter in MSW leads to toxic pollutant emissions such as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), which is a big obstacle to the promotion of Incineration technique. Activated carbon injection (ACI) with dual bag filter (DBF) is a major PCDD/Fs control device in MSWI. Commercial activated carbons applied by incineration power plant are mainly microporous carbon with a huge specific surface area, while mesopore within2-5nm is important for adsorption of PCDD/Fs. Research was carried out in this thesis which mainly focused on the development of specific mesoporous activated carbon and the adsorption of PCDD/Fs.Commercial activated carbon made from coconut, coal and wood were modified by HNO3.The results show that specific surface area can be increased effectively by modification. However the pore size distribution is not significant changed. Among three kinds of activated carbon, only wood-based one shows an increase in mesopore volume within2-5nm, which is also not significant.Wood-based activated carbon was then modified to prepare specified mesoporous activated carbon by Fe(NCO3)3-impregnation coupled with CO2activation. Process variables such as impregnation ratio, activation temperature and activation time were considered. The results show that when the impregnation ratio is1w%, the temperature is900℃, the rate of CO2is0.5L/min and the activation is2hours, the mesopore (2-5nm) volume of modified activated carbon could reach0.37cm3/g and account for62.1%of the total pore volume. The increasement of mesopore is caused by catalysis of Fe and erosion effect of NO2.Finally, an adsorption generator was applied for the adsorption of PCDD/Fs. Results show that compared to the original activated carbon, the modified one could have a larger adsorption capacity of PCDD/Fs. Its removal efficiency could reach72.8%, while the original activated carbon is only52.8%. And modified activated carbon can get to a saturation faster than the original one. On account of the solid adsorption between PCDD/Fs and mesoporous (2-5 nm)activated carbon, the modified activated carbon.shows an even adsorption ability to different chlorinated PCDD/Fs congeners.