Although polychlorinated biphenyls(PCBs) are globally recognized pollutant, an understanding of their resources as by products in chemical industry is poorly investigated. This paper presents data from a study that wa...Although polychlorinated biphenyls(PCBs) are globally recognized pollutant, an understanding of their resources as by products in chemical industry is poorly investigated. This paper presents data from a study that was conducted in order to determine the extent of PCBs in 1,4 dichlorobenzene( p DCB) mothballs. Total PCBs and dioxin like PCBs were detected in five mothball samples. Total PCB concentrations ranged from 328 ng/g to 1798 ng/g, while the levels of WHO TEQ were between 0 16 pg/g and 13 pg/g. Mean concentrations of total PCBs and WHO TEQ in the samples were 724 ng/g and 3.2 pg/g, respectively. The highest level of PCB congeners was that of trichlorinated biphenyls(537 ng/g), which maybe due to the relatively low chlorination in the process of p DCB production. A mechanism of the formation of PCBs from polychlorinated benzene in the presence of chlorine is also suggested. The results suggested that re estimation on the risk of p DCB products, especially the products for daily use such as mothballs, is expected.展开更多
o-Dichlorobenzene (o-DCB) was dechlorinated by Pd/Fe powder in water throughcatalytic reduction. The dechlorination reaction is believed to take place on the surface site ofthe catalyst via a pseuclo-first-order react...o-Dichlorobenzene (o-DCB) was dechlorinated by Pd/Fe powder in water throughcatalytic reduction. The dechlorination reaction is believed to take place on the surface site ofthe catalyst via a pseuclo-first-order reaction. The final reduction product of o-DCB is benzene.The dechlorination rate increases with the increase of bulk loading of palladium due to the increaseof both the surface loading of palladium and the total surface area. Dechlorination efficiencyaccounts for 90% at Pd/Fe mass ratio 0.02% and metal to solution ratio about 53.3g · L^(-1) in 120minutes. Dechlorination is affected by the reaction temperature, pH, Pd/Fe ratio and the addition ofPd/Fe. E_a is found to be 102.5 kJ · mol^(-1) in the temperature range of 287—313 K.展开更多
[Objective]The research aimed to study rapid dechlodnation kinetics of 1,4-dichlorobenzene （1,4-DCB） by microwave-assisted Raney Ni -AI alloy catalyst. [ Method] Microwave-assisted Raney Ni -AI alloy catalyst was us...[Objective]The research aimed to study rapid dechlodnation kinetics of 1,4-dichlorobenzene （1,4-DCB） by microwave-assisted Raney Ni -AI alloy catalyst. [ Method] Microwave-assisted Raney Ni -AI alloy catalyst was used for dechlorination of chlorobenzene （CB） and 1,4-DCB to analyze dechlorination kinetics of 1,4-DCB. [ Result] Reductive dechlorination reaction of 1,4-DCB by microwave-assisted Raney Ni- AI alloy catalyst was in accordance of the two-order reaction kinetics. Reaction rate constants of 1,4-DCB dechlorination at 35 and 50 ℃ were 0.037 6 and 0.151 mol/（ L . min）, and the activation energy was 76.66 kJ/mol. By microwave-assisted Raney Ni - AI alloy catalyst, dechlorination rate of 1,4- DCB reached 90% at 10 rain and 35 ℃. Moreover, two chlorine atoms were removed simultaneously, reaching the target of efficient dechlorination. [ Condusion] Oechlodnation of polychlodnated organic compounds by microwave-assisted Raney Ni- AI alloy catalyst obtained good effect .展开更多
文摘Although polychlorinated biphenyls(PCBs) are globally recognized pollutant, an understanding of their resources as by products in chemical industry is poorly investigated. This paper presents data from a study that was conducted in order to determine the extent of PCBs in 1,4 dichlorobenzene( p DCB) mothballs. Total PCBs and dioxin like PCBs were detected in five mothball samples. Total PCB concentrations ranged from 328 ng/g to 1798 ng/g, while the levels of WHO TEQ were between 0 16 pg/g and 13 pg/g. Mean concentrations of total PCBs and WHO TEQ in the samples were 724 ng/g and 3.2 pg/g, respectively. The highest level of PCB congeners was that of trichlorinated biphenyls(537 ng/g), which maybe due to the relatively low chlorination in the process of p DCB production. A mechanism of the formation of PCBs from polychlorinated benzene in the presence of chlorine is also suggested. The results suggested that re estimation on the risk of p DCB products, especially the products for daily use such as mothballs, is expected.
基金the Returnee Foundation of Ministry of Education of China (No. 2002-247)Science and Technology Project of Zhejiang Province (No. 2004C34006).
文摘o-Dichlorobenzene (o-DCB) was dechlorinated by Pd/Fe powder in water throughcatalytic reduction. The dechlorination reaction is believed to take place on the surface site ofthe catalyst via a pseuclo-first-order reaction. The final reduction product of o-DCB is benzene.The dechlorination rate increases with the increase of bulk loading of palladium due to the increaseof both the surface loading of palladium and the total surface area. Dechlorination efficiencyaccounts for 90% at Pd/Fe mass ratio 0.02% and metal to solution ratio about 53.3g · L^(-1) in 120minutes. Dechlorination is affected by the reaction temperature, pH, Pd/Fe ratio and the addition ofPd/Fe. E_a is found to be 102.5 kJ · mol^(-1) in the temperature range of 287—313 K.
文摘[Objective]The research aimed to study rapid dechlodnation kinetics of 1,4-dichlorobenzene （1,4-DCB） by microwave-assisted Raney Ni -AI alloy catalyst. [ Method] Microwave-assisted Raney Ni -AI alloy catalyst was used for dechlorination of chlorobenzene （CB） and 1,4-DCB to analyze dechlorination kinetics of 1,4-DCB. [ Result] Reductive dechlorination reaction of 1,4-DCB by microwave-assisted Raney Ni- AI alloy catalyst was in accordance of the two-order reaction kinetics. Reaction rate constants of 1,4-DCB dechlorination at 35 and 50 ℃ were 0.037 6 and 0.151 mol/（ L . min）, and the activation energy was 76.66 kJ/mol. By microwave-assisted Raney Ni - AI alloy catalyst, dechlorination rate of 1,4- DCB reached 90% at 10 rain and 35 ℃. Moreover, two chlorine atoms were removed simultaneously, reaching the target of efficient dechlorination. [ Condusion] Oechlodnation of polychlodnated organic compounds by microwave-assisted Raney Ni- AI alloy catalyst obtained good effect .
