| Aim at the actual demand for tobacco harm reduction and environmental protection,this research is focused on the design and synthesis of novel functional porous materials in order to capture the strongest carcinogen of tobacco special nitrosamines(TSNA)with higher efficiency and special selectivity.Besides,the template-free method for hierarchical porous carbon materials is preliminarily explored,on the basis of discarded cigarette butts.The main research content is as follows:1.Super-hydrophobic silicic xerogel(SG)was prepared from methyltrimethoxysilane(MTMS)and dimethyldimethoxysilane(DMDMS),and had the best elastic properties and mechanical strength when MTMS to DMDMS molar ratio was determined to be optimal 3/2.In order to increase its surface area(4 m2g-1)and adsorption capacity of TSNA,SG was modified by epitaxial growth of mesoporous silica to form the coated composite named as MSGx with a large surface area(152-208 m2 g-1)and pore volume(0.133-0.162 mLg-1).As a result,this new sorbent could further improve the removal of TSNA.Besides,the micron-sized SG could be transformed into siliceous hydrophobic nanoparticles,by means of mesoporous channels of SBA-15.The concentration of precursor solution was adjusted to master the distribution of hydrophobic particles and the SS-3 sample with appropriate hydrophobicity reached 150%increasing capacity of SBA-15 in liquid adsorption of TSNA.2.Considering the various influencing factors for captuing TSNA,a unique microenvironment was carefully created inside the channels of mesoporous silica MCM-41,which combined the contribution of an Al-containing mesoporous distorted channel,metal oxides modifiers and carbon particles.In situ carbonization of template micelles,combined with the excess aluminum used in one-pot synthesis of MCM-41,is adopted to tailor the tortuosity of mecsoporous channels,while loaded metal oxides(5wt%)and the Al component in the framework are employed to exert the necessary electrostatic interaction toward the target carcinogens TSNA in solution.Therefore,the typical 5%Cu/AM-10c sample had removed 0.3 mg g-1 of TSNA with the help of this unique microenvironment.Besides,the adsorptive property of 5%Cu/AM-10c would be further synthetically evaluated in various aspects,such as solid-to-liquid ratio,adsorption time,loading amount of CuO as well as types of tobacco extract solution.3.To meet the requirement of selective removing environmental carcinogen,elaborated microporous interspaces were successfully fabricated inside the channel of mesoporous silica SBA-15.The cigarette filters(CF)and ferric nitrate solution was infused into SBA-15 via wet impregnation method,and carbonized to form carbon and FexO particles tailoring the tortuosity of mecsoporous channels as well as provide the necessary electrostatic interaction towards TSNA in solution.Besides,the carefully modified SBA-15 displayed evidently selectivity towards 4-methylnitrosamino-1-3-pyridyl-1-butanone(NNK)and the representative sample Fe0.9CF1.2/S15c owned excellent performances in various tobacco solutions,with the high NNK-selectivity up to 58%,same as that of HZSM-5 zeolite.This strategy created new sorbents combining the high capability of mesoporous silica and the selectivity of microporous zeolite,giving certain enlightenment for new functional materials and environmental protection.4.A kind of hierarchical micro/mesoporous carbon composite had been successfully created with template-free method,on basis of cigarette filters and low-cost metal salts.The type and additive amount of metal salts took charged of structural properties and adsorptive property of hierarchical porous carbon composite.As a result,when the FexO-doped was at a range of 10%-16.5%,this sorbent achieved the best adsorptive property towards TSNA(29.4%-33.8%),especially the removal of NNK reaching above 98.9%duo to shape-selectivity of hierarchical structure.This research strategy of waste recycling was of great significance for environment protection,resource recycling and sustainable development. |
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