双模板剂体系下层状镁碱沸石的合成研究

通过直接水热合成法在吡咯烷和四甲基氢氧化铵双模板剂体系下制备出具有层状薄片组成的球形镁碱沸石,并且考察了四甲基氢氧化铵加入量对镁碱沸石的结晶度、晶化曲线、晶体形貌、比表面和孔结构的影响,采用X射线衍射(XRD)、扫描电镜(SEM)、氮气吸附脱附等手段对合成样品进行分析表征.结果表明:随着四甲基氢氧化铵加入量的增加,其晶化过程逐渐延长,但最终得到的镁碱沸石相对结晶度无明显变化;四甲基氢氧化铵的加入可以显著改变镁碱沸石的晶体形貌、比表面和孔结构.     

固相法合成NaA型粉煤灰沸石对染料废水的吸附性能研究

以粉煤灰为原料,采用固相法合成NaA型粉煤灰沸石.通过静态吸附实验,研究了吸附时间、pH值、溶液浓度以及吸附温度对粉煤灰沸石吸附脱除亚甲蓝性能的影响.通过SME、XRD对产品进行表征,探讨了亚甲蓝在粉煤灰沸石上的吸附行为.结果表明:经XRD分析,合成产物主要为NaA型沸石.SEM分析表明,产物分别具有纺锤体及NaA型沸石立方体骨架结构;在吸附温度25 ℃,pH值>5,粉煤灰沸石投加量8 g·L-1,吸附30 min时,NaA型沸石对初始浓度为50~100 mg·L-1的亚甲蓝去除率均可达90;以上,较粉煤灰提高了45;;与商品沸石的吸附性能相当.合成的粉煤灰沸石吸附亚甲蓝过程符合Langmuir模型,其为单分子层吸附.     

以粉煤灰为原料采用两步法制备高纯度ZSM-5型沸石的研究

采用经碱熔融-离心提取处理后的粉煤灰为原料,经水热反应研究两步法合成高纯度ZSM-5型沸石的过程,探讨了碱灰比、焙烧温度对硅铝溶出量的影响,研究了碱度、晶化时间、晶化温度与硅铝比对合成ZSM-5型沸石的影响.结果表明:碱灰比为2.3∶1,焙烧温度为680 ℃时可获得最高的硅铝溶出量;当SiO2/Na2O =7(摩尔比),SiO2/Al2O3=45(摩尔比),晶化时间为68 h,晶化温度为180 ℃时可获得高纯度的ZSM-5型沸石.     

高岭土水热合成4A沸石实验研究

水热法合成4A沸石的实验是在不同的碱度、不同的液固比、不同的晶化温度和不同的晶化时间条件下进行的,并进行了实验结果和各种合成因素的分析及研究.实验结果分析表明在加碱煅烧及合成沸石的过程中,使用NaOH的效果比使用Na2CO3和KOH,加入适量的晶种能缩短晶化反应时间并能提高合成沸石的质量.在碱度为2.5～4.0M、液固比6∶1～8∶1、晶化温度90～103℃以及晶化时间为3～5h的实验条件下,采用苏州高岭土合成了4A沸石.文中还采用X射线衍射仪和扫描电镜对合成的沸石样品进行了表征.     

KOH碱熔活化钾长石制取全钾W型分子筛

本文提出了KOH碱熔活化钾长石制备全钾W型分子筛的工艺.考察了KOH碱熔活化碱矿比、老化温度与时间、晶化温度与时间及反应体系组成等因素对合成W型分子筛形貌和结构的影响,结果表明W型分子筛在较宽范围的条件下可以合成,其中适宜的条件为:KOH与钾长石的碱矿比为2∶1,活化物料按K2O∶SiO2∶Al2O3∶H2O摩尔比15∶ 10∶1∶570来调整配比,25℃下老化2.5h,150℃下晶化24h.W分子筛合成后的母液一部分可在W分子筛制备中循环利用,另一部分可副产K2CO3和白炭黑,实现了原料的综合利用.     

利用稻壳制备X型分子筛及性能研究

以稻壳为硅源,采用水热法成功合成出了X型分子筛,并对亚甲基蓝染料进行吸附.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外-可见光谱和钙离子交换能力对样品的性能进行表征与测试.研究结果表明,提纯后稻壳灰为无定型态,其主要成分SiO2含量高达98.96;;水热法合成X分子筛的最佳配比为n(SiO2)/n(Al2O3) =3.8、n(Na2O)/n(SiO2)=1.4、n(H2O)/n(Na2O) =40,最佳水热晶化温度为100℃,最佳晶化时间为8h.在此条件下,合成产物无杂相,晶形发育完好,结晶度高,钙离子交换能力高达310.3 mg·g-1.亚甲基蓝溶液初始pH值在11 ～12范围内,初始浓度小于30 mg·L-1,分子筛用量在0.10～0.25 g范围内时,产物对亚甲基蓝有较好的吸附效果.     

热处理温度对碱沉淀法制备氧化锌的光催化性能的影响

采用硝酸锌为原料,分别以三乙醇胺、六次甲基四胺为沉淀剂,通过碱沉淀法制备了氧化锌光催化剂.以亚甲基蓝溶液脱色反应为模型,借助SEM、TEM、BET、XRD、TG、UV-Vis吸收光谱等表征手段,研究了热处理温度对氧化锌光催化剂催化活性和形貌的影响,并简要讨论了ZnO光催化亚甲基蓝的反应机理.结果表明,两种样品随着煅烧温度的升高,亚甲基蓝脱色率均先升高后降低,热处理温度为450℃时ZnO的光催化活性最强,亚甲基蓝脱色率达到86.7;;循环实验表明样品具有良好的稳定性和循环性.     

磁性Fe3O4/膨胀石墨对亚甲基蓝的吸附性能研究

以膨胀石墨(EG)为载体,采用简单的水热法,制备出磁性Fe3O4/膨胀石墨(MEG).采用X-射线衍射仪(XRD)和扫描电子显微镜(SEM)对MEG的组成结构和形貌进行表征.以亚甲基蓝为目标污染物,探讨了溶液pH值、吸附时间、盐离子浓度和亚甲基蓝初始浓度对吸附性能的影响,并对吸附动力学和吸附等温线进行研究.结果表明:当亚甲基蓝初始浓度为50 mg·L-1,pH值为7,吸附时间为60 min时,对亚甲基蓝的去除率和吸附量分别为97.03;和48.52 mg·g-1,随着溶液中盐离子Na+和Ca2浓度的增加,MEG对亚甲基蓝的吸附性能降低;MEG对亚甲基蓝的吸附行为符合拟二级动力学模型和Langmuir等温吸附模型.MEG可以使用磁铁进行分离回收,回收率达95.71;.5次吸附-再生后,吸附量仍较高为41.72 mg·g-1,说明MEG吸附剂具有较稳定的重复使用能力.     

粉煤灰-锰渣基地质聚合物原位水热法转化NaP型分子筛的工艺研究

以粉煤灰-锰渣基地质聚合物为前驱体,经水热合成法原位转化为NaP型沸石分子筛.利用单因素试验,探索硅铝比、锰渣掺量、碱浓度、水热时间和水热温度对沸石分子筛的抗压强度及钙离子交换能力的影响,得到了制备沸石分子筛的适宜条件为:硅铝比3.8、锰渣掺量40wt;、碱浓度3.0 mol·L-1、水热温度70℃、水热时间24 h.利用XRD、SEM、FT-IR和TG-DSC等手段对产物进行分析,结果发现制备的NaP型沸石分子筛结晶度高,呈钻石状,热稳定性较好,抗压强度为25.84 MPa,钙离子交换量达351.25 mg CaCO3/g.     

热处理对TiO2薄膜的影响及其光催化性能探究

以钛酸丁酯为前驱体,采用溶胶-凝胶法制备TiO2薄膜,探究不同热处理温度对TiO2薄膜的影响及其在紫外光催化下对亚甲基蓝的降解性能,通过热重分析仪(TG-DTG)、X射线衍射仪(XRD)、比表面积和孔结构分析仪、扫描电镜(SEM)、接触角测试对薄膜的热稳定性、晶相组成、比表面积和孔结构、表面形貌、接触角进行表征分析.结果表明:TiO2的晶型随着热处理温度的升高而发生从锐钛矿型到金红石型的相转变;不同热处理温度下TiO2不同晶型影响紫外光催化降解亚甲基蓝的效果;450℃热处理后的TiO2薄膜结构致密,孔径分布窄,在紫外光照射下对亚甲基蓝的降解率最好,经紫外光照射60 min后,其降解率为100;,且接触角最小为7.8°,表现出超亲水性.     

Crystallization properties of zeolite A synthesized from coal fly ash using a fusion/hydrothermal method

Abstract

Zeolitic materials were synthesized from coal fly ash (CFA) using the fusion/hydrothermal method. The effect of NaOH/CFA ratio and particle size on the morphological structure of the zeolitic material crystals prepared was investigated by analyzing crystals morphology and crystallinity. The chemical composition, morphology, and crystallinity of the synthesized materials were characterized by SEM, XRD, and XRF. It was possible to synthesize chamfered-edged cubic crystals at NaOH/CFA ratio of 0.9. The particle size of the zeolite crystals tended to decrease with increasing the alkali content of NaOH/CFA from 0.9 to 1.8. The morphological structure of the crystalline particles was similar to that of zeolite A synthesized from the CFA. This study has shown that the fusion/hydrothermal method is a very effective technique for synthesizing the zeolitic materials from the CFA and provides a potential application for obtaining commercial products.     

Synthesis of nano‐crystalline zeolite β: Effects of crystallization parameters

The effects of variation in Si/Al ratio (25 and 100) and crystallization temperature (80 °C to 180 °C, at an interval of 20 K) on crystal size of zeolite β were studied. Products obtained at different synthesis parameters were characterized by powder X‐ray diffraction, IR spectroscopy, thermal analysis, scanning electron microscopy and nitrogen adsorption. Increase in crystal size with crystallization temperature and Si/Al molar ratio was observed. Crystal morphology at 140 °C was spherical whereas at 180 °C it was of irregular shape. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

铁掺杂P型分子筛的合成及应用

采用水热合成法,按照摩尔比5Na_2O∶Al_2O_3∶8SiO_2∶xFe~(3+)∶(116～156)H_2O配料,草酸为铁离子的络合剂,经过室温搅拌成胶,100 ℃下于不锈钢反应釜中晶化20 h,合成了三种掺杂铁量不同的P型分子筛.利用XRD、FT-IR和SEM对产物进行了表征,分析结果表明铁掺杂P型分子筛与纯P型分子筛结构相同,其晶体粒度均匀且稍有增大;以合成的分子筛作为吸附剂考察了合成产物对水中氟离子、铅离子和钾离子的吸附性能,铁掺杂P型分子筛对氟离子的吸附性能明显增加,达到4.98 mg/g,而对铅离子和钾离子的吸附性能没有促进作用.     

Viscosity of metglas 2826 near the glass transition using rapid heating

An attempt was made to measure the temperature dependence of viscosity of Metglas 2826 near the glass temperature using rapid heating. This temperature region is normally inaccessible to viscous flow measurements due to crystallization. The melt viscosity, heat of fusion at the melting temperature, and the melting temperature itself were also measured. These parameters are used to calculate the critical cooling rate needed to avoid crystallization via standard nucleation/crystal growth/transformation theory.     

A more clear insight of the lysozyme crystal composition

Crystallization can be used as a purification method for proteins. Lysozyme was chosen as a model substance. Changing crystallization conditions will lead as shown to different lysozyme crystal morphologies with different properties. Beside others, lysozyme crystals can show a Tetragonal, High Temperature and Low Temperature Orthorhombic crystal morphology. Experiments such as conductivity measurements, pH tests, chloride detection tests, experiments using methylene blue as a dye and dissolution experiments were carried out to investigate the composition of the lysozyme crystals. It is proven that lysozyme crystals are made up of the initial buffer solution components: lysozyme (the protein), water which is part of the crystal lattice, salt ions which are attached to the protein molecule and voids filled with the buffer solution containing the crystallization agent (e.g. salt). Interesting dissolution behaviours of the lysozyme crystals were observed which are not described so far elsewhere (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

不同硅源原位合成莫来石及其性能

分别选用煤矸石、粉煤灰、黄沙、苏州土为硅源,工业氢氧化铝为铝源,氟化铝和五氧化二钒为添加剂,通过固相反应法原位合成了具有莫来石晶相的样品.采用X射线衍射仪和扫描电子显微镜对试样的物相结构和微观形貌进行了分析,研究了在不同的硅源下制备的试样性能及其结构的特征变化.结果表明:利用苏州土作为硅源能够合成具有针状形貌的莫来石晶相,分别以煤矸石和黄沙作为硅源合成了具有柱状形貌的莫来石和片状形貌的氧化铝晶相,而以粉煤灰作为硅源合成的主晶相为柱状的莫来石;并分别对不同硅源制备的试样的体积密度、显气孔率以及抗折强度进行了分析,探讨了莫来石的形成机理.     

Synthesis of cubic mesoporous silica and carbon using fly ash

A supernatant solution of silicate species extracted from coal fly ash in a power plant by alkali fusion was used under acidic conditions to prepare a mesoporous silica, SBA-16. SBA-16 was used as a template for the synthesis of a mesoporous carbon using sucrose as a carbon source. These mesoporous silica and carbon materials were characterized by XRD, N₂ adsorption-desorption, SEM, and TEM. Textural properties of the silica and carbon samples prepared using fly ash were found to be comparable to those prepared by pure chemicals, successfully demonstrating the feasibility of recycling fly ash for the synthesis of high quality porous materials.