水热法合成4A沸石的相变/纳米聚合生长过程及其机理研究

用廉价的硅铝系渣料为原料,通过水热法合成了4A沸石,根据不同时间的晶化反 应产物,用XRD、SEM等表征手段对4A沸石的形成机理及晶体长大过程进行了研究,结果 表明:①该反应过程的机理属前驱体固相→硅酸根或铝酸根液相→P型沸石晶相→P型沸石 向A型沸石的相变→A型沸石向P型沸石逆相变;②4A沸石晶体的长大是通过纳米聚合生 长的结果.     

作为炭材料前驱体的离子液聚合物的简易合成(英文)

采用一步法合成新型离子液聚合物,并以聚合物作为炭材料的前驱体。这种新型离子液聚合物的特征包括:聚合无需添加引发剂,聚合引入的阴离子能够控制材料的微孔大小。以含Cl-的离子液聚合物为前驱体合成的炭材料具有较小的比表面积(47m2/g),而以含较大(三氟甲基磺酰基)亚胺基阴离子的离子液聚合物为前驱体合成的炭材料具有较大的比表面积(595m2/g)。含二氰胺阴离子的离子液聚合物为前驱体合成的炭材料的比表面积为30m2/g。     

铜型抗菌沸石的合成(英文)

用液相、固相离子交换法将沸石与具有抗菌性能的铜离子合成抗菌沸石。用正交法确定了两种方法的较佳条件 ,并进行了比较。液相、固相离子交换法合成铜型抗菌沸石的较佳条件为硫酸铜浓度为 0 .1mol·L- 1 ,硫酸铜用量为 0 .0 2mol;温度分别为 60℃和 5 5 0℃ ,反应时间分别为 4h和 1h。尝试利用微波加热法合成抗菌沸石。微波加热合成抗菌沸石可以减少反应时间和节约能源     

不同形貌高炉渣基沸石的合成及反应机理的探讨

高炉渣是高炉炼铁过程中的副产品,是一种复杂的硅酸盐,高炉渣酸浸后的滤渣是硅凝胶,可以作为硅源,从而合成沸石。以高炉渣为前驱体,采用碱熔融-水热法合成不同形貌沸石,通过X射线衍射分析、扫描电子显微镜等表征手段探讨了最佳合成条件及反应机理。结果表明,体系中硅铝比为影响沸石结构种类的关键因素,n(Si)/n(Al)=0.4～1.2范围内,能够合成A型沸石;n(Si)/n(Al)=1.6～2.0范围内,能够合成八面沸石;n(Si)/n(Al)=1.4处为A型与八面沸石共存体系;八面沸石的形成需经过溶解—成核—结晶等几个过程,属于双相转化反应机理;合理控制晶化温度可将八面沸石转变为P型沸石。     

钾铯基地聚合物前驱体水热合成块体铯榴石

以偏高岭土为铝、硅源,以硅酸钾铯溶液为碱激发剂,无需添加任何沸石晶种和表面活性剂,室温制备了钾铯基地聚合物前驱体。将所制备钾铯基地聚合物前驱体在密闭蒸压反应釜环境中(180℃,0.8 MPa)水热晶化8h,制备得到了块体铯榴石。研究结果表明,钾铯基地聚合物前驱体为无定形物质;经水热晶化处理后,铯含量较高的样品中出现了铯榴石晶体,说明地聚合物凝胶原位转化为铯榴石晶体颗粒。原位转化生成的铯榴石晶体颗粒被地聚合物凝胶包裹和粘结,使得块体材料具有较高抗压强度。     

洗涤剂助剂的应用及研究进展

综述了洗涤剂助剂的研究进展.重点介绍了沸石类助剂包括4A和P型沸石的结构、钙镁离子交换性能、交换速度和液体携带量等,并与X及AX型沸石及其它类型的洗涤剂助剂进行了比较.分析对比表明,沸石类助剂对洗涤剂性能的提高及生产工艺的改善具有明显的优势,特别是有较好离子交换性能的MAP型沸石及较高液体携带量的AX型沸石有更加广阔的应用前景.     

二硼化锆陶瓷前驱体的制备与研究

介绍了一种二硼化锆陶瓷前驱体的制备方法.首先以氧氯化锆、邻羟基苯甲醇、乙酰丙酮为单体,在三乙胺作用下发生缩聚反应,合成出一种含锆聚合物.然后将该聚合物与硼酸在溶液中共混,除去溶剂后即得到二硼化锆陶瓷前驱体.用红外光谱、核磁共振和凝胶渗透色谱对含锆聚合物进行表征,用X射线衍射对二硼化锆陶瓷前驱体的配方及裂解温度进行优化分析.结果表明,所合成的含锆聚合物是一种以Zr-O-Zr为主链、乙酰丙酮与邻羟基苯甲醇配体为侧链的线性聚合物.该聚合物具有良好的溶解性,可与硼酸以1∶1.5的质量比在丙酮/乙醇溶液中共混,从而得到二硼化锆陶瓷前驱体.该前驱体在1400℃下的惰性气氛中裂解,可生成二硼化锆陶瓷粉末,其陶瓷转化率为30％左右.     

矿渣/偏高岭土复合前驱体原位转化沸石的影响因素研究

沸石具有良好的吸附、过滤、催化等性能，被广泛应用于建筑、农业、化工等领域。以碱激发胶凝材料为前驱体制备沸石是近年来开发的新技术，但纯偏高岭土基前驱体转化所得沸石往往存在机械强度偏低和界面分层的问题。鉴于此，本工作在前驱体中引入矿渣，发挥其高活性等效应，改善前驱体水热转化为NaA和NaP型沸石后试样的物理性能，研究了水热温度、水热时间及矿渣掺量等因素对沸石晶体种类、沸石转化率、抗压强度的影响。结果表明：在掺用矿渣条件下，提高水热温度，沸石晶体种类减少，沸石转化率先升高后降低；适当延长水热时间，沸石种类无明显变化，但沸石转化率升高；反应时间过长会导致沸石溶解，进而使得沸石转化率降低。矿渣可降低前驱体生成沸石所需的水热温度，缩短水热时间，提高样品强度，减弱分层现象。矿渣/偏高岭土前驱体转化沸石的适宜条件为矿渣掺量10%、水热温度110℃、水热时间20 h,此条件下水热后样品抗压强度达到62.2 MPa,沸石转化率达到70%。     

前驱体聚合物转化法制备SiBN(C)陶瓷纤维研究进展

SiC,Si3N4,BN等二元体系陶瓷纤维因具有优良高温机械性能、介电性能、高温稳定性能所以被广泛地应用,而相比较而言多元体系SiBN(C)陶瓷纤维正处于研究的初步阶段,但是因其综合了上述二元体系的各种优点,如高温热稳定性、高温耐腐蚀、抗氧化等性能所以已成为当前航空航天领域的研究热点,尤其是含碳量很低的SiBN陶瓷纤维具有很好的透波性能,在导弹天线罩上有重要的应用.其中前驱体聚合物转化法是SiBN(C)陶瓷纤维的主要制备方法,该方法的优点在于可通过前驱体聚合物的分子结构设计,得到含有目标元素的分子前驱体,并在聚合过程中调控其流变性能,从而获得具有可纺性的前驱体聚合物.主要概述了近年来国际和国内采用前驱体聚合物转化法制备SiBN(C)陶瓷纤维的几种方法,它们分别是含硼分子改性聚硅氮烷法,单体改性硼基前驱体法和小分子单体合成法.其中小分子单体合成法又分为多步法和一步合成法.用图表分析比较了各种方法的合成路线,SiBN(C)陶瓷纤维制品性能,以及存在的问题,并且提出了进一步研发的方向和建议.     

气相转移法制备多孔双相沸石复合物

采用气相转移法制备了同时含有Y和ZSM-5沸石的双相沸石复合物。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、N₂吸附-脱附和骨架红外(FT-IR)等手段对合成的样品进行了表征。结果表明, 合成的样品受Y型沸石的添加量、干胶制备条件和气相转移法转化条件的影响; 水热预处理后的ZSM-5沸石前驱体中具有ZSM-5沸石的骨架特征振动峰, 归结于ZSM-5沸石晶核或微晶的形成, 这有利于在气相转移法转化过程中引导或促使体系向ZSM-5沸石相的转变, 并有利于抑制ZSM-35杂晶的形成; Y型沸石在蒸汽处理过程中的脱铝过程导致合成的沸石复合物具有介孔结构。     

Removal of ammonium ion from aqueous solution by natural Turkish (Yildizeli) zeolite for environmental quality

The purposes of this study were to investigate the removal efficiency of ammonium (NH(4)(+)) ion from aqueous solution using the natural Turkish (Yildizeli) zeolite and to characterize equilibrium isotherms. Experiments were carried out using batch method as a function of the solution pH, shaking time, dosage of adsorbent, and temperature. All these factors affected NH(4)(+) ion removal from aqueous solution. Equilibrium modelling data were fitted to linear Langmuir and Freundlich models. Dubinin-Redushckevich (D-R) isotherm was applied to describe the nature of ion exchange of NH(4)(+) and found that it occurred physically. Thermodynamics parameters such as change in free energy (DeltaG degrees ), enthalpy (DeltaH degrees ) and entropy (DeltaS degrees ) were also calculated. These parameters confirmed that ion exchange of NH(4)(+) by the zeolite was feasible, spontaneous and exothermic in nature. Based on the results, it can be concluded that the natural Turkish (Yildizeli) zeolite is suitable for the removal of NH(4)(+) ions in wastewater treatments and agricultural purposes to in terms of sustainability of environmental quality.     

Comparative sorption kinetic studies of ammonium onto zeolite

The sorption kinetics of ammonium onto three types of zeolite, natural zeolite, natural zeolite covered by biofilm and ammonium-bearing zeolite covered by biofilm, at two particle sizes were studied. The pseudo-first order and pseudo-second order models were fitted to the results by a non-linear method. The batch sorption model, based on a pseudo-second order mechanism, was applied to predict the rate constant of sorption, the equilibrium capacity and the initial sorption rate. Ion exchange between NH(4)(+) and cations in the zeolite increased with decreasing particle size of the zeolite. Biofilm covered on the zeolite did not affect the ion exchange for the smaller particle size but decreased the ion exchange capacity by 22% for the larger particle size. In addition, bioregeneration should be considered for the recovery of ion exchange capacity of the bio-zeolite made from ammonium-bearing zeolite by the microorganisms in the biofilm, 78.0 and 63.9% regeneration for the smaller and larger particle size of zeolite, respectively.     

污泥-高钙煤系废物制备地聚合物的技术与性能

鉴于地聚合物是一种低碳排放且能源、资源消耗较少的新型胶凝材料,其制备技术倍受关注。采用热活化污泥和高钙煤系废物制备地聚合物,并与采用高钙粉煤灰和矸石制备地聚合物的反应机制与性能进行了对比分析,确定了制备污泥-高钙煤系废物地聚合物的最佳工艺参数。采用XRD、SEM、TG-DTA及FTIR等对制备的地聚合物的原料组成和性能进行了深入分析。研究表明: 经900℃焙烧45 min掺量为40%(＜50 μm)热活化污泥-煤系废物制备的地聚合物具有较好的抗压强度。无定形地聚合物胶凝包裹在球状粉煤灰颗粒周围,有类沸石矿物生成,Al—O/Si—O对称伸缩峰及Si—O—Si/Si—O—Al弯曲振动峰明显。     

湿凝胶晶化法高效合成X型沸石及其离子交换性能研究

沸石分子筛由于具有丰富的孔道结构、大的比表面积、良好的稳定性和择形性能而被广泛应用于诸多工业领域。开发高效、节能、操作简便的新型分子筛合成路线具有十分重要的意义。在传统水热合成方法的基础上进行改进,采用湿凝胶晶化法制得X型沸石分子筛。采用XRD、SEM、N_2吸附-脱附测试对产物的结构进行了表征,并研究了分子筛的产率、单釜利用率以及Ca~(2+)交换性能。结果表明,湿凝胶晶化法制备的X型分子筛保持了其微孔骨架结构,单釜利用率大幅提高,并且表现出良好的Ca~(2+)交换性能。     

通过固相交换法制备的（Li,NH4）-LSX分子筛骨架中Li+的分布

采用固相交换法对NH4-LSX分子筛进行Li+交换,详细考察了交换温度和交换时间以及LiCl·H2O与分子筛的摩尔比对其结构与性能的影响,并得到最佳交换条件,由此制备出不同Li+交换度的锂型低硅铝比X型分子筛((Li,NH4)-LSX),采用XRD、FT-IR、SEM、TG和NMR等手段对其进行表征,探讨了不同交换度的(Li,NH4)-LSX分子筛骨架中Li+的分布数量和结构变化。     

Preparation,structure and hydrothermal stability of alternative (sodium silicate-free) geopolymers

In this contribution, we present the preparation and structural characterization of a new type of alternative (sodium silicate-free) geopolymer system. A new procedure of geopolymer synthesis based on the preparation of a reactive geopolymer precursor by direct calcinations of low-quality kaolin with Na/K hydroxides is introduced. The subsequent formation of geopolymer matrix does not require activation by alkaline silicate solution. The compact and hardened material was prepared only by adding a small amount of water. Besides the introduction of a new synthetic procedure, we focused also on the systematic study of chemical structure, mineralogical composition and hydrothermal stability of the prepared geopolymer systems as seen by solid-state NMR spectroscopy and powder X-ray diffraction (XRD). An important part of our contribution is the demonstration of structural and mineralogical changes induced by hydrothermal treatment and long-term aging of the prepared geopolymers. It was found that redistribution of basic structural units (SiO₄⁴⁻ and AlO₄⁵⁻) and gradual formation of zeolite fractions can be related to the observed changes in mechanical properties. Up to a certain level, the presence of zeolites enhances the mechanical properties of the prepared geopolymer systems. However, the additional formation of a new generation of zeolite fractions, occurring over the long-term period causes an inversion of this trend and a dramatic reduction of mechanical strength. Nevertheless, formation of the geopolymer matrix by alkaline and thermal activation of low-quality kaolin has the potential to be used in ecological problems solving (solidification of powdered and dangerous waste materials).     

Preparation of geopolymer precursors by sol–gel method and their characterization

Pure Al₂O₃–2SiO₂ precursors (powders) for a geopolymer were prepared by a sol–gel method. The alkali-activated products derived from the precursors meet the general criteria for a geopolymer. The structure of the powders was investigated by NMR, XRD, and FTIR analysis, and their alkali-activation properties were studied. The data show that the powders when heat treated at 200 °C begin to contain 5-coordinated Al, those heat treated at 300 °C can begin to undergo alkali-activation, and those heat treated at 300–800 °C possess a number of structure characteristics similar to metakaolin, and the properties of their alkali-activated products are similar to those of the metakaolin geopolymers.     

Ammonium exchange in leakage waters of waste dumps using natural zeolite from the Krapina region, Croatia

The paper presents the results of investigating the treatment of leakage waters from waste dumps using activated carbon and natural zeolite clinoptilolite, known as a very selective and efficient cation exchanger for ammonium ions. The results are presented of chemical and physical analyses of leakage waters characterized by a high content of ammonium (820 mg L(-1)) and organic pollutants (1033 mg L(-1) C). Physical and chemical characteristics of zeolite and the exchange of ammonium ions in model and real solutions were determined in laboratory trials. Treatment of leakage water with 0.04-2.5% (w/w) activated carbon (Norit 0.8 Supra) led to a reduction of total organic carbon in leakage water from 1033 to 510 mg L(-1). Pretreatment of leakage water with activated carbon did not improve the exchange of ammonium ions on zeolite. Without pretreatment of leakage water, the exchange of ammonium ions amounted to 4.2 mg NH4+/g zeolite. Addition of activated carbon, regardless of its mass, increased the exchange of ammonium ions to only 5.7 mg NH4+/g zeolite. In the model solution of an equal concentration of ammonium as the real solution, 17.70 mg NH4+/g zeolite was exchanged. Organic pollutants that were not eliminated by activated carbon (most probably components of natural origin) adsorbed to zeolite and prevented the exchange of NH4+ ions, which was also reduced due to the presence of K+ and Ca2+ ions.     

高岭土合成4A分子筛及其表征

采用ＴＧ－ＤＴＡ、ＸＲＤ、ＳＥＭ等现代测试技术以及测定钙离子交换量的方法研究了焙烧高岭土与碱液作用制备４Ａ分子筛的反应过程,给出了采用高岭土制备４Ａ分子筛扔最佳条件,并提出了以焙烧高岭土合成的４Ａ分子筛其形成机理应以异相成核为主,焙烧高岭土的碱液溶解为融洽上合成过程的控制步骤的新观点。