Experimental Study On PCDD/Fs Adsorption Onto Graphene Meterials

The dioxins emission from municipal solid waste incineration is always an issue concerned by public.Various carbon materials,such as activated carbon?AC?,carbon nanotubes?CNTs?have either been applied in practice or recently proposed to reduce dioxins emission,both in engineering practice and theoretical studies.However,graphene and nano-graphite are only studied by theoretical studies or simulator investigation in removing dioxins.In this study,nano-graphite and graphene were applied to adsorb dioxins.The research work and some main valuable conclusions are as followed.Nano-graphite powder?graphite?was applied to adsorb dioxins using a laboratory-scaled generating system.The effects of dioxins's concentration,adsorption temperature and adsorption time were investigated.The high mesopores volume and pore structure of graphite are critical factors to adsorb dioxins.The remove efficiency?RE?was effected by vapor pressure and temperature.Adsorption is an exothermic process,remove efficiency would decrease as the temperature increases and the highest RE was achieved when temperature is 150?.With the increase of concentration,it would be quick to achieve adsorption saturation due to the saturation and adsorption sites.PCDD/Fs had a concentration value up to which no adsorption occurred,long retention time is needed when the concentration is low.A laboratory-scaled PCDD/Fs generating system was developed to study the adsorption of dioxins by physical and chemical graphene with the concentration of 10.41 ng I-TEQ Nm^-3.The effects of graphene dosage,adsorption time and different temperature were investigated.RE of dioxins by both graphene increases with the increase of dosage,the adsorption efficiency of RGN1 was higher than that of RGN2.The REs of 17 toxic PCDD/Fs congeners are different,which is attributed to the vapour pressure.Low-chlorinated congeners are less adsorbed on graphite than high-chlorinated congener.The ?-? interactions formed by graphene sheets and compounds with benzene rings,which can enhance the adsorption of graphene.