十六烷基三甲基季铵阳离子改良二氧化硅对酸性染料的吸着

The sorption behavior of acid dyes onto cetyltrimethylammonium bromide (CTAB)-modified silica as a function of pH in the aqueous medium was studied. Single-and multi-solute sorption equilibria of orange Ⅱ（OR), phenol red (PR) and Eriochrome Black T (EBT) were studied at pH 3, unbuffered water pH and pH 11. Sorption behavior of EBT could not be conducted at pH3 due to its aggregation in acidic medium. All the reaction conditions, experimental protocols and techniques remained the same throughout the sorption process. Sorption isotherms for single-solute system were fitted by the Langmuir model, while Langmuir competitive model (LCM) and the ideal adsorbed solution theory (IAST) coupled with Langmuir model (IAST/Langmuir) were used for the prediction of multisolute competitive sorption. Sorption affinities influenced by the factors like physical interactive forces between the molecules of CTA on silica and sorbate, structural limitations of the dyes based on their geometrical arrangement were investigated. Sorption affinity of OR was found to be higher than that of EBT and PR at all the pH values investigated. Magnitude of the sorption capacities was observed to be higher in acidic medium but lower in alkaline medium. Trends of the sorption affinities in multisolute system were simlar to those in single-solute system but magnitude of the sorption capacities was significantly reduced due to the prevailing competition among the sorbates.     

Micellar association in simultaneous presence of organic salts/additives

Viscosity measurements under Newtonian flow conditions had been performed on cetyltrimethylammonium bromide (CTAB) aqueous solutions in the combined presence of sodium salts of aromatic acids (sodium salicylate, NaSal; sodium benzoate, NaBen; sodium anthranilate, NaAn) and organic additives (1-hexanol, C₆OH; n-hexylamine, C₆NH₂) at 30°C. On addition of C₆OH or C₆NH₂, the viscosity of 25 mM CTAB solution remained nearly constant without salt as well as with a lower salt concentration. This is due to low CTAB concentration which is not sufficient to produce structural changes in this concentration range of salts. However, as the salt concentration was increased further, the effect of C₆OH/C₆NH₂ addition was different with different salts: The viscosity first increased; then a decrease was observed with the former while with C₆NH₂ a decrease followed by constancy appeared in plots of relative viscosities (η _r ) vs. organic additive concentrations. At further higher salt concentration, the magnitude of η _r was much higher. The viscosity increase is explained in terms of micellar growth and the decrease in terms of swollen micelle formation (due to interior solubilization of organic additive) or micellar disintegration (due to formation of water + additive pseudophase).     

AlPO4-5分子筛大晶体的合成

研究了阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)对水热晶化法合成AlPO4-5大晶体的影响.实验过程中以拟薄水铝石为铝源,正磷酸为磷源,三正丙胺为模板剂,在晶化原液中添加一定量的氢氟酸、异丙醇以及CTAB.通过改变CTAB的添加量,在晶化温度180℃,晶化时间24.0 h的条件下,合成出了大而完美的六角棱柱形的AlPO4-5晶体,晶体尺寸可达890 μm×120 μm.实验结果表明,晶体的大小及完美程度与表面活性剂中烷基三甲基铵阳离子与晶化液中的负电荷基团[AlF6]3-和[PF6]1-的吸附作用有关.     

相转移催化氧化合成苯甲酸

研究了季铵盐CTAB催化高锰酸钾氧化氯化苄合成苯甲酸的反应。考察了CTAB用量、高锰酸钾用量、反应温度、反应时间对反应的影响。结果表明,合成苯甲酸的最优条件为:高锰酸钾与氯化苄的摩尔比为2∶1,CTAB的摩尔分数为氯化苄的8%,反应温度90℃,反应时间为3h,苯甲酸的产率可达89%。     

一种适用于地衣总DNA提取的改进方法

目的：针对地衣初生、次生代谢产物丰富的特点,提出了一种适于地衣总DNA的提取方法。方法：应用改良的CTAB法,对3种常见地衣进行了总DNA提取,经过琼脂糖电泳、紫外吸收分析DNA质量。结果：3个样本DNA的A260/A280值均在1.8～2.0之间,琼脂糖电泳图像清晰。结论：改良的CTAB法简便、省时、价廉,适合于地衣总DNA的提取,获得的DNA含量高,纯度好。     

介孔分子筛MOM-41的合成及其孔径的调节

以十六烷基三甲基溴化铵为表面活性剂，正硅酸乙酯为硅源在酸性条件下合成具有完好六方结构的介孔分子筛MCM-41；利用1，3，5-三甲基苯（TMB）作为辅助剂对介孔分子筛MCM-41的孔径进行调节．结果表明：酸性条件下能够合成结构完善的介孔分子筛并且利用XRD、扫描电镜对其进行详细的表征，有代表完好六方结构的特征峰及孔道的存在；此外，1，3，5-三甲基苯（TMB）可以有效增大分子筛的孔径，并且通过N2吸附-脱附对其孔径的大小进行详细表征。     

Study on Properties and Structural Parameters of Microemulsion CTAB／Butanol／Cyclohexane／Salt Aqueous Solution

SrAl2 O4∶Eu2 ,Dy3 isanewlongafterglowlu minescencematerialdevelopedinthe 1990s .Owingtoitsexcellentpropertiessuchashighluminescencein tensity ,longafterglowtime ,goodstability ,longsur vivalandwiderangeofexcitationband ,etc .,thema terialhasreceiveda…     

基于Theil指数的我国区域物流差异发展趋势研究

文章以我国31个省级区域物流为研究对象,结合Theil指数模型构建了分析区域物流差异发展趋势的模型,并借助2001²011年统计数据进行了实证分析,结合区域经济差异相关指数,剖析了区域物流差异发展的趋势。研究结果表明,相关政策的颁布与实施对区域物流差异发展具有很大影响;区域经济发展基础对区域物流发展差异程度会产生一定的干扰;区域物流发展可在一定程度上弱化区域经济的极化;各地区应当首先关注内部差异问题,再考虑向外部拓展的发展模式;发展的目标并不是完全消除差异,而是分析如何在差异中寻找发展机遇。     

Solution combustion synthesis of ZnO powders using CTAB as fuel

Zinc oxide (ZnO) powders have been prepared by solution combustion synthesis method using cetyltrimethylammonium bromide (CTAB) as fuel. The effects of fuel to oxidant ratios (? = 0.5, 0.75, 1 and 1.5) on the combustion behavior, phase evolution, microstructure, optical properties and photocatalytic performance were investigated by thermal analysis, X-ray diffractometry, electron microscopy, and diffuse reflectance spectrometry techniques. The slow decomposition rate of CTAB guaranteed the direct formation of single phase and well-crystalline ZnO powders regardless of fuel content. The specific surface area of the as-combusted ZnO powders with platelet particles increased from 21 ± 1 to 35 ± 2?m²/g with fuel content. The band gap energy also increased from 2.99 to 3.13?eV due to the decrease of particle size. The as-combusted ZnO powders at ? = 1.5 exhibited the highest photodegradation (~69%) of methylene blue under ultraviolet light irradiation, due to their good crystallinity and smaller particle size.     

Thermal and mechanical properties of polyamide 11 based composites reinforced with surface modified titanate nanotubes

The preparation of polyamide 11 (PA11) based composites reinforced with pristine and surface-modified titanate nanotubes (TTNT) is reported. Twin-screw melt compounding was used to produce composites with up to 2 wt% of TTNT. To enhance dispersion and TTNT compatibility with the thermoplastic, these were modified with cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS). Fourier transform infrared spectroscopy and thermogravimetry were used to demonstrate that surface modification prior to composite processing was successful, while scanning transmission electron microscopy combined with energy-dispersive X-ray analysis confirmed the retention of surfactants on TTNT in composites. Nevertheless, scanning and transmission electron microscopy revealed incomplete dispersion of TTNT inside polyamide. The improved wettability on the TTNT–PA11 interface was observed for composites comprising surface-modified TTNT. Consequently, these composites exhibited better thermal and mechanical properties than those containing pristine TTNT. A significant rise of the decomposition temperature was detected in composites containing TTNT modified with CTAB, while the uppermost increment of the storage and Young’s modulus (of about 35% and 26%, respectively) was achieved in the composite comprising 0.5 wt% of TTNT modified with SDS. The increase of the nanofiller content improved the yield strength and led to the drop in the strain at break.