Nitrosamines Removal And Nitric Oxide Release By New Functional Molecular Sieves

Molecular sieves have been applied extensively in the adsorption/separation and heterogeneous catalysis fields. Recently, both selective adsorption in the solution and potential application in life science require development of novel functional materials. The research concerning synthesis and application of functional materials is meaningful for environmental protection and healthcare fields. Absence of adsorption activated sites and competitive adsorption of other molecules hamper the actual capability of the mesoporous silica in complex system. Accordingly, the material modified with special functional groups is designed and prepared. Organic group is introduced onto material, in order to elevate utilization efficiency of nanospace of the sample. Moreover, the property-function of the resulting modified composites is studied in detail by using in-situ FTIR, TG-MS, and NMR techniques.1. Effective environmental protection material is prepared. Adsorption of nitrosamines in aqueous solution containing the tobacco-extract, by zeolite and mesoporous silica is investigated in detail. The influence of structural parameters such as pore size, Si/Al ratio and cations on the adsorption capability of zeolite is examined. Introducing aluminum species into mesoporous silica MCM-41 can overcome the disadvantage of lacking adsorption activated sites, thus the adsorption ability of Al-MCM-41 prepared with different modification methods is explored. Moreover, the impact of modifier amount, state and dispersion degree on the actual adsorption of the Al-containing composite is investigated to inspect their property and function.2. The hydrophobic character of adsorbent is crucial for adsorption of TSNAs in aqueous solution. Organic 3-chloropropyltriethoxysilane (CPTES) is then employed to functional ize the ordered porous silica through direct co-condensation and post-synthesis grafting methods, respectively. Besides, aluminum is also incorporated into the framework of MCM-48 to enhance the adsorption capability of nitrosamines. As the result, about 70% of TSNAs can be removed by the chloropropyl-modified Al-containing mesoporous silica, obviously exceeding that by activated carbon, which offers a strategy enhancing the adsorption efficiency of molecular sieve in the solution.3. Cubic laid mesoporous silica is synthesized using vinyltriethoxysilane (VTES) as additive through a phase transition method. VTES not only acts as the organic-functionalizing agent in the synthesis, but also influences the interaction between the cationic surfactant and silica oligomers, further controls the surfactant packing and prepares expected mesostructures through tailoring the charge density of micelles. We have also examined the factors of controlling the formation of mesostructures, such as VTES additive amount, pH value, aging temperature and time, providing formation mechanism of cubic Ia3d structure. Furthermore, properties of the resulting mesoporous silica in gaseous adsorption of phenol and liquid adsorption of phenylalanine are evaluated.4. A new strategy for releasing biologically relevant amounts of nitric oxide (NO) in the digestive system is proposed, in order to overcome the shortcoming of traditional NO-delivery manner. The amount of NO released can be tuned by altering the structure and modifier species of the zeolite. Various factors, including pH value, the temperature of acid solution, the volume ratio of liquid to solid, and the release time, are investigated to provide understand the NO release mechanism from the moisture-saturated zeolites. We find that nitrite is produced in acid solution, which has advantages for controlled NO release because it provides an active storage mechanism for NO, which is proved by in-situ FTIR experiments.5. A novel multifunctional molecular sieve as both an efficient releaser and a selective trapper, say, releasing NO and adsorbing nitrosamines simultaneously in digestive system, is developed to exploit utilize efficiency of nanospace. Different types of moisture-saturated molecular sieves are used as the NO-delivery and nitrosamine-capture vessels in mimic gastric juice after the modification of 3-aminopropyltriethoxysilane (APTES). APTES modification dramatically increases the capability of the vessel in NO release in acidic solution, because more NO can be adsorbed in the composite. Hierarchical structure of mesoporous zeolite material realizes the controllable APTES modification in which a lot of aminopropyl groups are grafted in mesopores while the zeolitic structure is kept, so the resulting sample exhibits high capability in releasing NO and adsorbing nitrosamines.6. Adjusting micelles nanospace through temperature-controlled method, storage and release of guest molecule on as-prepared mesoporous silica is realized. As-made samples with various symmetry mesostructures are synthesized by using different surfactants. Subsequently, guest molecules NO and menthol are adopted to validate the temperature-controlled "on-off’ effect of micelles. Specifically, the samples adsorb guest molecule at high temperature, store at low temperature for period of time, and then release the molecule at operating temperature.