【作者】 张群；

【导师】 胡立江；

【作者基本信息】 哈尔滨工业大学 ， 无机化学， 2010， 硕士

【摘要】 本课题研究工作致力于合成介孔材料,寻找合适的原料合成POSS材料来改性介孔材料,使改性后的分子筛能够提高去除饮用水中氨氮的效率。研究用正硅酸乙酯为硅源,P123为模板剂,采用水热晶化法直接合成出SBA-15分子筛。用稻壳灰和3-甲氧基巯丙基硅烷为原料用溶胶-凝胶法分别合成八聚四甲基铵POSS和八聚巯丙基POSS。然后对这两种POSS材料进一步官能化,分别改性介孔材料SBA-15分子筛,得到POSS-COOH和POSS-SO₃H改性SBA-15分子筛。对合成出的材料进行了以下表征:质谱、红外光谱（FT-IR）、透射电镜（TEM）、扫描电镜（SEM）、小角XRD、氮气吸附/脱附分析。合成的POSS材料用质谱进行表征,分析表明有相应的POSS材料生成,并进一步用红外光谱进行分析验证POSS的生成。采用小角XRD表征了SBA-15和改性的分子筛的结构,结果显示分子筛的二维六方的形态没有发生改变。红外光谱被用来显示改性后官能团的变化,谱图中特征峰的出现说明了POSS分子筛与分子筛链接起来。三种分子筛的微观结构用透射电镜进行表征,通过TEM清楚的看到改性剂进入分子筛后内部结构的变化。SEM照片清楚的反应了颗粒的表面形貌的变化,因此对三种分子筛进行了SEM表征,通过照片可以清楚的看到颗粒尺寸、形状的变化。运用各种模型,通过氮气吸附/脱附分析定量的计算出三种孔材料比表面积、孔径、孔容的大小,与SBA-15分子筛相比,POSS-COOH改性的分子筛平均孔径变大,孔容变小,比表面积变小,而POSS-SO₃H改性的分子筛平均孔径、孔容、比表面积都变小,定量的证实了POSS改性剂对分子筛的影响。合成出的三种分子筛用于饮用水中氨氮的去除。研究了吸附时间、吸附温度、氨氮浓度等因素对吸附量和去除效率的影响,比较了三种分子筛去除氨氮的效果,结果显示吸附时间越长,吸附量越大。吸附温度越高,吸附率越高。起始浓度越大,越有利于吸附。分子筛投加量越大,吸附量越大。同时两种改性分子筛中,POSS-SO₃H改性分子筛去除氨氮的效率更高。为了验证实验结果,用MS软件中相应的模块模拟和计算改性分子筛中氨氮吸附和离子交换的过程,结果显示POSS-SO₃H改性的分子筛中氨氮的扩散系数大,交换吸附需要的活化能低,因此更容易处理氨氮,验证了实验结果。更多还原

【Abstract】 This study is dedicated to synthesis POSS-modified mesoporous molecular sieves to improve the efficiency of ammonia-nitrogen removal from drinking water.Based on tetraethoxysilane and P125 template, the original SBA-15 molecular sieve was synthesized using hydrothermal crystallization method. The POSS modifiers, （Me₄N）₈(OSiO_1.58 （OSA） and （SHC₃H₆）₈(OSiO_1.5)₈, were prepared using rice husk ash and （3-mercaptopropyl）trimethoxysilane, respectively, through the sol-gel process, and further POSS-COOH and POSS-SO₃H modified SBA-15 molecular sievesThe SBA-15 molecular sieves before and after the modifications were characterized by standard techniques: mass spectrometry （MS）, infrared spectroscopy （FT-IR）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, small angle XRD and nitrogen sorption porosimetry （NSP）. The MS spectra shown narrow molecular distributions for the three molecular sieves, and the FT-IR spectra shown the corresponding groups before and after the modifications; the small-angle XRD peaks and TEM images represente micro-pore structures of the three SBA-15 molecular sieves; SEM images give clearly the changes of particle surface morphology （particle size and shape） before and after the modifications; NSP measurement determined the morphology of the SBA-15 molecular sieves before and after the modification, giving surface areas, pore diameters and pore volumes quantitively. Comparing with those of original SBA-15 molecular sieve, the pore diameters and pore volumes of the POSS-COOH modified SBA-15 molecular sieve increased but the surface area decreased; for the POSS-SO₃H modified SBA-15 molecular sieve, all those decreased. Above facts conclude that the POSS-modified SBA-15 molecular sieve can be made and increased in active groups to remove ammonia-nitrogen from drinking water.The influence of adsorption time, adsorption temperature and ammonia-nittrogen concentration on adsorption capacity and removal efficiency was investigated. The results shown that the longer adsorption time, the higher adsorption temperature, and higher initial concentration can lead to greater adsorption capacity and adsorption rate. Also, the experimental data shown that the two kinds of POSS-modified SBA-15 molecular sieves had greater ammonia-removing efficiency.The mentioned increase tendency was validated using a molecular dynamic simulation program of the Materials Stutio software to calculate the diffusion behavior of ammonia-nitrogen in the pores of three SBA-15 molecular sieve, and to compare transition–state energy of the ammonia-nitrogen removal reaction in the SBA-15 molecular sieve before and after modification.更多还原