【作者】 谭美易；

【导师】 袁明亮；

【作者基本信息】 中南大学 ， 材料学， 2010， 硕士

【摘要】 X型沸石具有独特的孔道结构和较大的比表面积,宏观上表现为具有优良的择形催化性能、分子筛分性能和离子交换性能,广泛应用于石油加工催化、气体分离、水处理等领域中。但不管其用作催化剂还是吸附剂,一般都存在一个共同的问题,即在催化和吸附各个操作单元中都需要进行快速的固液分离。本文在沸石合成过程中将磁性物质引进沸石结构中制备出较高稳定性和吸附性能的磁性沸石,分析了合成条件的影响及其对铅离子的吸附性能。采用在X型沸石合成体系中引入含Fe3O4的四乙基氢氧化铵前驱体的方法成功的对沸石进行磁化改性。结构分析表明,Fe3O4客体没有破坏沸石基体的晶体结构和孔道特性。铁元素没有进入沸石骨架,Fe3O4与沸石发生了化学键合作用。磁性X型沸石具有较高的热稳定性,最高耐受温度为500℃。该材料结合了沸石的吸附性能和Fe3O4的磁性,在实际应用中通过外加磁场使饱和磁性X型沸石粉体与作用体系分离,解决了X型沸石与母液分离困难的问题。为研究合成条件对产物的晶体结构和磁性能的影响,在不同的合成条件下合成了一系列的磁性沸石产物。结果表明,晶化温度越高或时间越长,产物结晶度越好,磁性能越差。但超过100℃,产物开始发生转晶,磁性也有所增强；加入磁性前驱体的量越多,产物结晶度越低,磁性能越好。另外,磁性液体分散剂的不同,也会影响产物的晶体生长和磁性能。以水为分散剂的产物其结晶度要好于以TEAOH为分散剂的产物,但磁性能要差。磁性能较佳的产物的饱和磁化强度为10.5 emu/g。综合性能较佳的样品的合成条件为：晶化温度80℃,晶化时间为8 h，加入14 mLFe3O4/TEAOH溶液。其饱和磁化强度为5.4 emu/g, Pb2+的单位质量吸附剂的单层饱和吸附容量为414.94 mg/g。本文还研究了磁性X型沸石对铅离子的吸附性能。结果表明,磁性X型沸石对铅离子具有较强的吸附力；单层Langmuir型吸附模型能较好的模拟磁性沸石对Pb2+的吸附。吸附条件对产物的吸附效果有重要的影响,在铅离子初始浓度为200 mg/L的条件下,固液比为0.2 g/L时的吸附容量最大；在吸附操作中较佳的吸附时间为2 h。更多还原

【Abstract】 X zeolite behaves excellent properties of shape selective catalysis, molecular sieves and iron-exchange for its unique tunnel structure and large specific surface area. They have been wildly used in many areas such as catalyst in oil industries, gas separation and water treatment. However, there is a common problem no matter they used as catalysts or sorbents, that is, quick seperation of solids and liquids is required in many operations of catalyze and adsorption. In this paper magnetic core has been introduced into the zeolite structure and magnetic zeolite with high stability and adsorption properties have been prepared. Synthesis conditions and adsorption of Pb2+ also have been studied.Magnetization modification on X zeolite has been successfully done by adding precursor of magnetic Fe3O4 TEAOH solution in the zeolite synthesis system. The structure analyses show that Fe3O4 object doesn’t damage the crystal structure and tunnel characteristic of zeolite base. Iron doesn’t buildup zeolite framework. Fe3O4 have combined with zeolite by chemical bond. Magnetic X zeoite has high thermal stability, whose resistant temperature is about 500℃.This material combined adsorption of zeolite and magnetism of Fe3O4. They can be separated from action system by outer magnetic field, which solves the problem of separation from mother liquid as a result.Magnetic zeolites have been synthesized in different conditions to investigate the effect of preparation conditions on the structure and magnetism of products. It seems higher crystallization temperature or longer crystallization time can lead to better crystallnity while worse magnetic properties. But when the crystallization temperature is over 100℃, crystal transformation appears and the saturation magnetization will rebound. In addition, with the volume of magnetic precursor increasing, the crystallnity descend while the magnetic property rises. The higher value of saturation magnetization among those products is 10.5 emu/g. The product with the better comprehensive properties have been obtained in conditions of 80℃,8 h and 14 mL Fe3O4/TEAOH solution. its saturation magnetization is 5.4 emu/g and monolayer adsorption capacity of Pb2+ per mass sorbent is 414.94 mg/g.Meanwhile, adsorption of magnetic X zeolite on Pb2+ is studied. It can be concluded that magnetic X zeolite have high adsorbability on Pb2+. The Langmuir monolayer adsorption model is better to simulate the adsorption of magnetic zeolite on Pb2+. Adsorption conditions greatly affect the results. When the initial concentration of Pb2+ is 200 mg/L and solid-liquid ratio is 0.2 g/L the adsorption capacity climb the top.The better adsorption time in adsorption process is 2 h.更多还原