Rare earth separation with 1-hexyl-4-ethyloctyl isopropylphosphonic acid extractant

A new extractant 1-hexyl-4-ethyloctyl isopropylphosphonic acid (HHEOIPP or HA) in heptane was employed to extract rare earths from hydrochloric acid medium. The dependence of extraction distribution ratio on equilibrium aqueous pH and the concentration of extractant were investigated. On the basis of slope analysis,it was proposed that two different kinds of extracted species were formed. For rare earth elements (La similar to Ho) the extracted species was LnA(3)(HA)(3) and for heavy rare earth elements (Er similar to Lu) the species was LnClA(2)(HA)(3). The steric hindrance plays an important role in forming the species. The extraction constants and separation factors of the adjacent rare earths were calculated too. Compared with HDEHP and HEH/EHP, HHEOIPP is a valuable extractant with high separation selectivity. The "tetrad effect" between K-ex and atomic number was observed.

Synthesis and characterization of optically active aromatic polyimides derived from 2,2 '-bis(2-trifluoro-4-aminophenoxy)-1,1 '-binaphthyl and aromatic tetracarboxylic dianhydrides

Optically active 2,2'-bis(2-trifluoro-4-aminophenoxy)-1,1'-binaphthyl and its corresponding racemate were prepared by a nucleophilic substitution reaction of 1,1'-bi-2-naphthol with 2-chloro-5-nitrotrifluorotoluene and subsequently by the reduction of the resulting dinitro compounds. a series of optically active and optically inactive aromatic polyimides also were prepared therefrom, These polymers readily were soluble in common organic solvents such as pyridine, N,N'-dimethylacetamide, and m-cresol and had glass-transition temperatures of 256 similar to 278 degrees C. The specific rotations of the chiral polymers ranged from 167 similar to 258 degrees, and their chiroptical properties also were studied. (C) 1999 John Wiley & Sons Inc.

Preparation, characterization of solid solution La4BaCu5-xMnxO13+lambda (x=0-5) and its catalytic activity in the reduction of NO by CO

A series of layered mixed oxides La4BaCu5-xMnxO13+lambda(x = 0-5) was prepared, characterized and used as catalysts for NO+CO reaction. It was found that all the samples were single phase having a structure with five-layered-perovskite. La4BaCu2Mn3O13+lambda showed the highest activity in the title reaction, this could be attributed to the synergetic effect between Cu and Mn. The results of TPR, TPD and excess oxygen investigations confirmed that the Cu ion would be the active center. The displacement of the Cu ion by Mn caused the Cu ion to be more easily reducible and more content of excess oxygen, and it was beneficial to the activity of the catalyst. The reaction mechanism was also proposed.

Particulate multilayers prepared from surfactant-stabilized SnO2 nanoparticles

Surfactant-stabilized SnO2 nanoparticulate organosol was prepared. The organosol mixed with arachidic acid was spread on water surfaces in a Langmuir-Blodgett (LB) balance. Surface pressure versus surface area isotherms were determined. The surfactant-stabilized SnO2 nanoparticulate monolayers were transferred, layer-by-layer by the LB technique, to solid substrates. Then the multilayers were characterized by Fourier transform IR spectroscopy, UV-visible spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The results indicate that the multilayer is composed of SnO2 nanoparticles and arachidic acid. It forms a Z-type periodic structure with a long spacing of 7.48 nm, i.e. a kind of three-dimensional superlattice. (C) 1999 Elsevier Science S.A. All rights reserved.

(Ce_(0.8)RE_(0.2))_(1-x)M_xO_(2-δ)固体电解质的溶胶-凝胶合成及其电性质

利用溶胶 凝胶法合成了 (Ce0 .8RE0 .2 ) 1-xMxO2 -δ(RE :稀土 ,M :碱土 )系列固体电解质 ,XRD表明 80 0℃即形成萤石结构 ,较高温固相反应合成温度低约 70 0℃ .测定了样品的电导率和阻抗谱 .XPS测试表明 ,掺杂碱土氧化物后吸附氧浓度明显增大 ,氧空位增多 ,电导率和氧离子迁移数增大 ,改善了CeO2 基固体电解质的性能 .讨论了碱土及稀土离子对电性质的影响 .(Ce0 .8Sm0 .2 ) 1-0 .0 5 Ca0 .0 5 O2 -δ80 0℃时电导率0 1 2 6S·cm-1,氧离子迁移数 0 .99.

Synthesis and characterization of poly(amide imide)s containing cyclohexylidene moieties with bulky substituents

Novel poly(amide imide)s (PAI) containing alkyl-substituted cyclohexylidene moieties were synthesized by conventional polycondensation of trimellitic anhydride chloride with novel aromatic diamines followed by chemical imidization using acetic anhydride and pyridine. The inherent viscosities of the resulting PAIs are relatively high and range from 71 to 112 mt g(-1). The prepared PAIs show excellent thermal stability and good solubility. The glass transition temperatures (T-g) measured by DSC are observed in the range of 312-342 degrees C. Furthermore, all the polymers are readily soluble in less hygroscopic organic solvents like cyclohexanone, gamma-butyrolactone as well as aprotic polar solvents.

可溶性聚酰亚胺LB膜对碳钢的缓蚀作用的研究

应用可溶性聚酰亚胺(PI)Langmuir-Blodgett(LB)膜沉积在碳钢电极上，研究其在中性及酸性介质中对碳钢的缓蚀作用．结果表明PILB膜在中性及酸性介质中对碳钢有较好的缓蚀作用，单分子层数目对缓蚀效率有很大的影响.

甲烷与二氧化碳重整制取合成气反应的研究 (I)Sr_(1-x)La_xNiAl_(11)O_(19)催化活性表征

对具有磁铅石结构的Ｓｒ１－ｘＬａｘＮｉＡｌ１１Ｏ１９对甲烷与二氧化碳重整反应的催化活性、积炭量和稳定性进行了研究．不同还原温度下催化剂的ＸＲＤ和催化活性的实验结果表明，金属镍是ＣＨ４＋ＣＯ２重整反应的活性组分，金属镍含量越大，反应活性越高．反应后催化剂积炭量的分析结果说明，在相同镍含量和分散度的情况下，Ｌａ３＋离子对Ｓｒ２＋离子调变，可以降低催化剂的表面酸性，提高催化剂的抗积炭能力．ＬａＮｉＡｌ１１Ｏ１９是一种具有较好催化活性、稳定性和抗积炭性能的催化剂.

Study on the two class glass transition and ion transport of a comb polymer electrolyte

The thermal behaviour and ion-transport properties of a comb polymer electrolyte CP350/LiSCN based on methyl vinyl ether/maleic anhydride copolymer with oligo-oxyethylene side chains were studied by means of DSC and ac impedance method. The two glass transition temperatures which can be attributed to side chains and main chains respectively were found to increase with increasing salt concentration. Conductivities which displayed non-Arrhenius behaviour were analyzed by using Vogel-Tammann-Fulcher equation and interpreted on the basis of the configurational entropy model derived by Gibbs and coworkers. The optimum ionic conductivity at 25 degrees C achieved was 2.19x10(-5)S/cm.

Pd(OAc)_2/FePc催化环己烯氧化合成环己酮的研究

考察了几种Ｆｅ大环配合物与Ｐｄ（ＯＡｃ）２组成的双组分催化体系，在乙腈酸性水溶液中环己烯氧化合成环己酮的催化活性．实验结果表明，其中以酞菁铁（ＦｅＰｃ）与Ｐｄ（ＯＡｃ）２组成的催化体系活性最高，而ＦｅＴＰＰＣｌ与Ｐｄ（ＯＡｃ）２催化体系，虽然催化活性较高，但催化剂的稳定性较低．各种因素对Ｐｄ（ＯＡｃ）２／ＦｅＰｃ催化活性影响的研究结果指出，在无水和酸存在的非水溶液中，Ｐｄ（ＯＡｃ）２／ＦｅＰｃ对环己烯氧化未显现出任何催化活性．认为在乙腈酸性水溶液中，Ｐｄ（ＯＡｃ）２／ＦｅＰｃ催化环己烯氧化合成环己酮的作用机理与Ｗａｃｋｅｒ催化剂的作用机理相似，ＦｅＰｃ是起再生作用的催化剂.

梳状高分子固体电解质的二级玻璃化转变及离子传输研究

研究了交替马来酸酐共聚物多缩乙二醇酯(CP350)-LiSCN配合物的热行为及离子传输特性.实验表明:CP350/LiSCN配合物在所研究[Li]/[EO]配比范围呈均相无定形并具有二级玻璃化转变.两种玻璃化转变温度均随盐含量的增加而上升.离子电导率随盐浓度的变化而出现一极大值,室温电导率最大可达2.19×10~(-5)S/cm.导电行为符合VTF方程.

钒元素在铬铝丙烷氧化脱氢催化剂中的助催化作用

研究了丙烷在以钒元素为助剂的ＣｒＡｌＯ催化剂上的氧化脱氢反应性能。利用ＸＲＤ、ＤＲＳ、ＸＰＳ等方法，讨论了钒元素的助催化作用。实验结果表明，钒元素的添加，使得催化剂表面产生Ｏ物种，并且可以改变催化剂的表面组成，提高催化剂表面Ｃｒ３＋的浓度，从而影响催化剂的氧化脱氢活性。

《热分析》评介

热分析技术应用甚广,尤其自80年代初我国开始热分析学会活动以来,10余年间我国在该领域取得了长足的进步,尽管相继出现了一些热分析的译著和专著,但适于作教材的著述,由蔡正千编写的《热分析》(高等教育出版社1993年出版)还是第一本。作者基于多年从事热分析教学和科研的切身体会和坚实基础,用简明的语言,阐述了热分析的一些基本问题,作到了言简意赅,深入浅出。表现出如下一些明显特点: ·本书作为教材详简适度,布局合理。全书258页,21万字。首先从基本的物理化学概念,如物质的热学性质和热量传递等入手,接着讲解几种主要的热分析方法,再讲一些典型的应用示例。从上述几个侧面,可让学习者通过为数不多的课时就可了解热分析总的概貌。

二茂铁-AQ修饰碳纤维微葡萄糖传感器的研究

本文用二茂铁、AQ成功地制备了微葡萄糖传感器。Eastman-AQ(AQ-55D,AQ29D)是一种新型的聚合物(磺酸酯)阳离于交换剂,涂于电极表面上,形成的膜除具有强的附着力外,同时还具有预富集、离子交换及防污性能。制得的电极具有制作方法简单、快速、重现性好,抗干扰能力强等特点。检测上限15.0 mmol/L,响应时间小于6s。由于AQ强的附着力,二茂铁及酶的流失较小。电极的稳定性有所提高。

电子束法沉积ITO膜的XPS研究

采用电子束蒸发法制备了均匀、致密、透明导电的ITO膜。讨论了其光电性能,并用XPS技术研究了ITO膜的表面组成、结构和状态。