Study On The Methods Of Reducing Tar In Tobacco With Hexagonal Mesoporous Silica(HMS)

HMS (hexagonal mesoporous silica) synthesized under neutral conditions based on long-chain primary amine as template is a hexagonal structure mesoporous silica molecular sieve with large surface area, large pore volume, and uniform pore size. Compared to other molecular sieve, HMS has thick frame walls and abundant surface hydroxyl groups. Furthermore we adopted a relatively mild template removal method in the HMS synthesis process and the template is recyclable, reducing costs and environmental pollution. Therefore it is widely used in the field of catalysis, adsorption, separation,sensors, molecular engineering, nano-composite materials and so on. However, molecular sieves with simplex adsorption of HMS can not meet the requirements in the practical application. By surface modification introducing organic or inorganic groups into molecular sieves,we can improve its adsorption selectivity and widen its applications.In this study, we synthesized a large surface area mesoporous molecular sieve HMS at room temperature with molecular self-assembly synthesis, using long chain primary amine dodecylamine (DDA) as template agent and TEOS (TEOS) as silica source. Then HMS was modified with Lanthanum doped and PEG. XRD, SEM, TEM, infrared spectroscopy (FTIR), TG, and N2 adsorption were used to characterize the materials. We also studied the effects of the material in reducing tar content of cigarettes, and detected the toxicity of the materials with cytotoxicity experiment. The results showed that:(1) Using long-chain primary amine as template, the hexagonal mesoporous molecular sieves can be synthesized,which are spherical particles with honeycomb pore structure under neutral conditions, with large surface area (1478.95m2g-1), large pore volume, and uniform pore size.,and can be used as an ideal subject for nano-objects to build nano-materials;(2) Doped La-HMS kept the original mesoporous structure. Doped Materials can be evenly distributed in mesoporous silica matrix. In the synthesis of La-HMS mesoporous solid process, there is strong interaction between the template and silicate. Rare earth ions is helpful to promote the condensation of silanols of the mesoporous solid and so reduce the Si and O (H2O) interaction. The presence of 960cm-1 band can not be directly used to prove that rare earth ions have been doped into HMS mesoporous solid. EDS showed that no new element appears, which means rare earth ions have been doped into HMS mesoporous solid. Though doped materials have reduced its surface area, but it still maintains a large surface area. The surface area of La-HMS is 1020.12m2g-1. Compared with the raw material, rare earth lanthanum doped material used in cigarettes has a better adsorption. (3) the modified PEG-HMS also maintained the original mesoporous structure, the added PEG did not destroy the mesoporous structure. PEG is adsorbed on the HMS particle surface by hydrogen bonding,which do not have no chemical reaction. The modified material surface area decreased slightly, but still maintains a large value, PEG-HMS specific surface area is 1015.65m2g-1. Thermal stability of PEG-HMS composites increased compared to the PEG Cell compatible of PEG-HMS Composite improved compared to HMS, and it is no toxicity. A new composite material with both the advantages of the two materials was produced by combining two materials. Its selective adsorption has a good application in adsorpting harmful substances in cigarettes.(4)HMS, La-HMS and PEG-HMS was added into cigarettes in the initial study. And it was found that the additive materials have certain effect in absorption and degradation for smoke tar and nicotine in cigarette. But it needs further study before it was used as an industrial product.(5)MTT results showed the prepared materials in this study are not toxic.Toxicity levels range from 0 to1, with no significant difference compared to the control group. At the 5th day,and the 7th day, the proliferation rate of cells exceeded over the control, indicating the material is favorable to the cell proliferation, which may be related to the material structure. In this study hexagonal mesoporous materials was adopted. The mesoporous structure is conducive to cell adhesion. And the material itself is non-toxic, which is beneficial to cell proliferation. Accordingly, the hexagonal mesoporous materials can be used as cigarette additives; it also has very good prospects in biological medicine.