No abstract

The electron-beam technology was applied to reduce the emission of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in a flue gas of 1000 m(3)N/h from the municipal solid waste incinerator (MSWI) at a temperature of 200 degrees C. More than 90% decomposition of PCDD/Fs was obtained using an electron accelerator at a dose of 14 kGy. The decomposition was initiated through reactions with OH radicals produced by the irradiation of flue gases, followed by oxidation such as the ring cleavage of the aromatic ring, the dissociation of ether bond, and dechlorination. The cost analysis estimated that the electron-beam system can cut the annualized cost by approximately 50% for the treatment of PCDD/Fs in a pre-dusted MSWI flue gas as compared with a bag-filter system when operating on electricity generated from an incineration. Electron-beam technology is an economically and technologically useful method for reducing PCDD/Fs in an incineration flue gas.

No abstract

Novel elastic gel was obtained by immersing paste of sodium carboxymethylcellulose (CMC) in acid solution. The paste was prepared by mixing CMC and water at the concentration of 20%. Water absorption and mechanical strength of the resultant gel were evaluated after removing uncrosslinked CMC and acid. Combination of radiation crosslinking and the immersion in acid resulted precise molding and dimension stability of the gel. Maximum mechanical strength of the gel at 50% compression increased with acid concentration for the unirradiated and the irradiated samples at 5-20kGy. The gel prepared by irradiation at 5-lOkGy and the immersion did not cause rupture after 50% compression and was more than 100 times stronger than the radiation-crosslinked gel. The reason of the mechanical strength was attributed to crosslinks formed by the acid treatment The crosslinks by the irradiation had been referred to chemical bonds, whereas, those by acids were caused by hydrogen bonds, which was elucidated by FT-IR, ICP and TG-DTA measurements. Sodium in the carboxymethyl groups is replaced by hydrogen in the acid solution. The hydrogen bonds induced the decrease of CMC solubility in water and formed the elastic gel.

No abstract