Study Of Molecular Sieve Materials On Tobacco Harm Reducing And Temperature-Controlled Release

Porous mateials, especially molecular sieves, have been widely applied in the adsorption, separation and heterogeneous catalysis fields. This research is focused on the synthesis and application of functional porous materials for environmental protection and healthcare. Aiming to the demand on environmental protection and health care, we design novel porous metarials through the control of structure, morphology and chemical compositon and determine their properties by advanced technique such as in-situ FTIR, LC-MS/MS, GC-MS and so on.1. Novel absorbent-releaser is discovered by utilizing the micelles in as-synthesized mesoporous silica. The template of cetyltrimethyl ammonium bromide (CTAB) in the as-synthesized MCM-48or MCM-41have spoke-like configuration inside the channel which is able to intercept and capture the NO or menthol in the gas phase. For NO, once it is absorbed on these composites with CTAB, it forms surface nitrous species and nitrates that are stable in atmosphere, achieving the long-term storage of NO in ambient environment. Finally, the NO can be acid-triggered released in the solution with the pH value same as that of the gastric juice. For menthol, the as-prepared mesoporous silica can adsorbed it into inner channels at high temperature when the micelle is soft, then lock and store it at room temperature for a long period and releasing it when the temperature rise again. This research provides a new low-cost candidate for delivering exogenous guest.2. We attempted to create a hierarchical structure in the molecular sieve for the trap of nitrosamine to combine the adsorption advantage of zeolite and mesoporous silica. This type of mesoporous zeolite was fabricated through impregnating structure-directing agent into the as-synthesized MCM-41followed by dry-gel conversion. The texture of mesoporous ZSM-5was tailored by adjusting the Si/Al ratio in the MCM-41source and the thermal treatment time. Volatile nitrosamine N-nitrosopyrrolidine (NPYR) was used as probe molecule in instantaneous gaseous adsorption; and liquid adsorption of N-nitrosonornicotine (NNN) in dichloromethane and tobacco-specific nitrosamines (TSNA) in tobacco-extracting solution. As expected, mesoporous zeolite exhibits a good adsorption capacity in laboratory tests, superior to either microporous zeolite or mesoporous silica, providing a valuable candidate for controlling nitrosamines in the environment.3. To expand heterogeneous catalysis to the pollutant removing in environment, molecular sieves are directly put into the tobacco rod of cigarettes as the cigarette-catalyst (cig-cat) to in situ eliminate the tobacco-specific nitrosamines (TSNA) in mainstream smoke during combustion of cigarette. Several zeolites and mesoporous silicas are utilized for comparison, in order to assess the impact of pore size, Al content, morphology and acid-base property on the reduction of TSNA in smoke. When these additives are activated as the hot zone in burning cigarette approaches, they can remove the TSNA up to35%in the smoke of Burley type tobacco, and most of these additives can keep their structure after tobacco combustion. These results provide a new way of controlling the environment pollution caused by smoking.To enhance the selectivity of TSNA removal in tobacco smoke, ferric zeolite ZSM-5and Y to is prepared by both aqueous ion-exchange and wet-impregnation, and characterized by XRD, UV-vis DRS, H2-TPR and temperature-programmed surface reaction (TPSR). These samples were put into tobacco rods of cigarette to assess their real performance in reducing TSNA content in smo(?)e. Results show that the ion-exchanged zeolites are more active than their impregnated analogs and the ferric Y zeolite could selectively reduce up to26%of total TSNA in mainstream smoke of Burley type tobacco. By comparing the degradation of NPYR in TPSR and TSNA in practice we found that the trend is similar, indicating catalytic breaking of the chemical bond in N-NO group of nitrosamines is the key step of decomposition of these carcinogens.The design and preparation of a clustered zeolite microsphere are realized for the target of selective catalytic degrading of tobacco specific nitrosamine (TSNA) carcinogens without affecting the particulate matter in tobacco smoke. A new method of using organic amine TMAOH as bifunctional template is utilized by a one-step hydrothermal crystallization without any post-treatment or other shape-directing agent. It has a rugged surface like a cluster of crystal grains; when it was directly mixed with tobacco shred, it can avoid the interference of particulate matter in smoke and shows a high selectivity in the removal of TSNA. This synthetic method offers a novel way of preparing zeolites with a spherical morphology, which has great potential application in the fields of catalysis, adsorption and separation.4. Liquid adsorption of tobacco specific nitrosamines (TSNA) in the tobacco extracting solution by porous materials is carried systematically for the first time with the monitoring of standard LC-MS/MS technique, in order to reduce the environmental cancerogens in smoke at the source. Various types of adsorbent are utilized and their performance was measured by spectrophotometric along with LC-MS/MS methods. Both measurements gave the same variation tendency on the nitrosamines analysis. The influence of pore size, cations and organic modification were carefully investigated, and the optimal liquid conditions were determined, in which CaA zeolite and modified mesoporous silica CAM48-10sample can capture34%and46%of TBMA in the tobacco solution, offering an efficient way for controlling nitrosamines in environment at source.MTNS and DMDS are used to synthesize the marshmallow-like superhydrophobic silica aerogel material, which is applied to the adsorption of oily substance as nitrosamines in tobacco extractingsolution and performs superior to the normal mesoporous silica SBA-15.Besides, the mesoporous silica is epitaxy grown on the surface of the aerogel in weak acid condition to form an exogenous shell on it. The approach increases the adsorption capacity of the aerogel material and further enhances the removal proportion of nitrosamines and TSNA in aqueous solution.