| Recently,"Precision" is put forward in medical fields and it also plays an important role on the study of adsorption and catalysis.This research is focused on the selecting,design,and synthesis of novel functional porous materials in order to realize the precise adsorption and catalysis of 4-methylnitrosamino-1-3-pyridyl-l-butanone?NNK?,which is the strongest carcinogen in tobacco special nitrosamines?TSNA?.The ZSM-5 zeolite with proton or sodium cation,ZnO modified activated carbon,graphene based materials and PAN I coating mesoporous silica can recognize and remove NNK selectively.The reason of selective adsorption and the catalysis of zeolite towards NNK are explored by in-situ FTIR,TG/MS technology and theoretical calculation.1.The concept about "precise adsorption-capture" is used to control the pollution of TSNA carcinogens in environment.Liquid adsorption of TSNA in tobacco extract solution and aqueous solution by zeolite including A,Y and ZSM-5 zeolites is systemically studied with the monitor of LC-MS/MS technology.CaA zeolite showed the highest adsorption capacity among these zeolites but NaZSM-5 zeolite had the best selectivity to NNK in tobacco extracting solution.In the aqueous solution of N'-nitrosonomicotine?NNN?and NNK,NaZSM-5 zeolite was able to distinguish precisely the subtle structural difference between NNN and NNK,and adsorbed all of the spindly NNK molecules but refused bulky NNN.This is the first evidence that zeolite recognizes and traps TSNA molecules by ultra-fine confinement effect.In addition,NaZSM-5 zeolite could degrade the adsorbed TSNA into less toxic compounds at lower temperature than that of pyrolysis,avoiding formation of volatile nitrosamines and secondary pollution.HZSM-5 zeolite showed a higher TSNA adsorption capacity than that of NaZSM-5 zeolite in aqueous solution due to proton and optimal Si/Al ratio,and it kept the preferent adsorption of NNK in tobacco extract solution.The adsorbed efficiency of HZSM-5 spraying on the rod of cigarette?18 ng/mg-zeol?was inferior to the TSNA removal with liquid adsorption at source?36 ng/mg-zeol?,providing a valuable clue on the strategy for tobacco harm reducing.Both FTIR and TG/MS technologies were employed to study the adsorption and catalytic degradation of NNN and NNK by HZSM-5 zeolite.The N-N bond of NNK was broken in the range of 423-573 K and the pyridine fragments appeared at 630 K due to the breakage of C-C bond between pyridine and carbonyl groups,realizing the degradation at relatively lower temperature.2.Activated carbon?AC?owns some advantages in liquid adsoption of TSNA because of its high surface area and good hydrophobility.In order to endow AC the zeolite-like selective adsorption capability,acid soak,ion-exchange or wet impregnation combined with temperature programmed carbonization method were used to modify AC.ZnO impregnated sorbent 5ZnAC could remove 56%of TSNA in industrial tobacco extract solution.Moreover,this adsorbent showed selectivity for spindly NNK,having a zeolite-like fine confinement effect.Accordingly it is feasible to construct selective adsorption sites in the disordered coarse porous materials.TSNA adsorbed on 5ZnAC could be eluted by CH2Cl2 and enriched by the re-adsorption of NaZSN-5 zeolite,which provides a new way to control TSNA hazards and make waste profitable.New shape-selectivity of graphene was discovered.Graphene and carbon nanotubes lacked fine-geometric confinement but they preferably captured the spindly NNK among the components of TSNA either in aqueous solution or tobacco extract solution.Also,they showed an abnormal selectivity to trap the bulky acid red 88 rather than the smaller methyl orange.According to theoretical calculation,electronic interaction such as ?-? interaction induced this new selectivity in adsorption.With new selectivity,graphene showed a higher capacity and adsorptive rate of TSNA than the typical selective sorbent ZSM-5 zeolite in tobacco solution due to the unlimited diffusion and mass transfer resistance,paving a new way to control the carcinogens like TSNA in environment.3.Polyaniline?PANI?was controlled carefully to grow at different sites such as near the pore opening,in the channel or on the outside of SBA-15 by in situ-synthetic and post-synthetic methods.The influences of aniline additional order,aniline to organosilicone ratio and with or without template were investigated in order to obtain the optimal generational site of PANI.Different sites of PANI on SBA-15 were confirmed by TEM,N2 adsorption-desorption?BET?characterization and zeta potential measurement.PANI grew preferentially in the channel when proper amount aniline was added previous to silicon source.If aniline was added after the silicon source,PANI grew mainly on the outside surface of SBA-15.The location of PANI was in the pore entrances of SBA-15 once the aniline was put into the solution containing template-free SBA-15.The resulting composites realize different selectivity TSNA and tobacco alkaloids in tobacco extract solution.1P-S15 sample possessed a best TSNA adsorptive capacity?23.2%?.FTIR spectrum of TSNA in 1P-S15 and quantum calculations demonstrated that the adsorption of TSNA is controlled by hydrogen bonding.4.Zinc chloride was utilized as the multi-functional modifier with dicyandiamide to synthesize porous g-C3N4.It not only played the role of pore-former in the resulting composite,but also acted as the assistant in succeeding adsorption of methyl orange?MO?.Adjusting the quantity of ZnCl2 additive combined with the concentration of acidic washing liquid could control the amount and distribution of residual zinc species in the g-C3N4,in order to enhance the activity of the photocatalyst.The resulting composites were characterized by XRD,SEM,UV-vis diffuse reflection spectroscopy and XPS and so on,in order to assess the influence of residual zinc species on the physical and optical property of the composite.And they were evaluated in the photocatalytic degradation of MO in the visible light region,exhibiting a surface area 170%and an activity 240%higher than that of g-C3N4. |
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