铝先生的诊疗

自铝第一次被化学家发现并在实验室制备至今,铝一直与人类如影随形,铝及其化合物在生产和生活中有着重要的应用。本文将铝拟人化,以"诊疗"的形式,采用对话体,回顾了铝的发现史和应用史。     

沸石结构中骨架铝、非骨架铝固体~(27)Al NMR研究

应用乙酰丙酮络合沸石结构中非骨架铝的性质。建立了固体静态~(27)Al NMR定量测定沸石结构中骨架铝、非骨架铝比率的方法。论证了小角度脉冲和自旋晶格弛豫时间是准确定量的重要条件。同时还考察了水和乙酰丙酮对沸石骨架铝、非骨架铝结构的影响,认为干燥沸石中骨架铝存在于不对称结构中,水分子可以改变其周围电荷分布,提高其结构对称性。非骨架铝存在于极端不对称结构中,其与乙酰丙酮的络合物溶于乙醇溶液中,并具有液体核磁共振行为,因而在计算骨架铝信号强度时须乘上35/9换算因子。     

移动氢源用铝合金制氢技术研究

铝具有资源丰富、价格低廉、易保存、水解产氢量大(1244mLg-1)等特点,是NaBH4水解产氢的理想替代品[1].本文用机械球磨法制备了系列铝合金,并对其与水反应产氢的性能进行了研究.结果表明:锡和铋能提高铝的活性,其与铝形成的合金能在常温下与水反应.但铝锡合金在常温下与水反应速度缓慢,而铝铋合金能与水迅速反应,产氢率可达80%.     

铝在氢氧化钠溶液中的电化学行为研究

铝是地壳中含量丰富的元素 ,分布广泛 ,由于其具有价格低、能量密度高、导电性良好及无毒性等优点 ,因而是阳极材料的首选物质 ,铝电池的研究也已经成为近年来研究开发的热点课题之一[1～ 3] 。探讨铝在强碱性溶液中的溶解机理 ,对铝电池的研究和开发将具有一定的理论指导意义。1　实验部分1 1　仪器与试剂ＢＡＳ 1 0 0Ａ电化学系统 (美国ＢＡＳ仪器公司 ) ;ＣＳ5 0 1型恒温槽 ;工作电极为直径是 0 .3ｍｍ的铂圆盘电极 ,参比电极是标准甘汞电极 (ＳＣＥ)。铝( 99.99% ) (天津化学试剂厂 ) ,氢氧化钠为分析纯(上海化学试剂厂 ) ,水为二次蒸…     

由烷氧铝合成有机铝聚合物及其主要应用

本文就从烷氧铝合成有机铝聚合物的方法及有机铝聚合物的分类,作较详细的综合评述,并对其主要的应用作归纳和总结。     

铝基材料水解制氢技术

氢能作为一种高焓值的绿色能源在解决未来能源危机和环境污染中备受关注,而铝水反应在众多制氢途径中被认为是最具优势的方法之一。本文着重论述了近几年铝基材料水解制氢技术的研究进展。铝水制氢是一种很有发展前景的储存和运输氢能的方式,但Al表面致密的氧化层阻碍了铝水反应的进行,使其难以在常温常压情况下产生氢气。为充分开发利用氢能源,可采用添加碱、氢化物、金属氧化物、无机盐等方式,或将金属单质与Al通过烧结、熔炼、球磨等先进的技术手段进行复合,能够有效地活化Al,从而实现低环境温度、短诱导时间、快产氢速率、高转化率的铝水反应,为燃料电池电动汽车现场供氢。     

铝对人类智能的损害及其对策的研究

论述了铝对人类智能的影响。铝的来源主要包括环境铝,食物性铝,炊具中的铝和药源性铝。铝对人类智能危害的基本原理是铝可进入大脑,与脑神经结合形成脑组织神经原纤维缠结和老年斑。防治的方法是减少污染,及时应用铝络合剂排出体内的铝。     

钴铝和锌铝水滑石的合成

采用低过饱和共沉淀法合成了一系列锌铝和钴铝水滑石,其结构经IR和XRD表征。研究结果表明,两类水滑石晶体结构相似;钴铝水滑石的稳定性高于锌铝水滑石。     

铝/水反应可控制氢

铝是地壳中最富有的金属元素,理论上可100%重复利用。铝/水反应所提供的绿色能源--氢能,很有可能解决人类将面临的能源短缺和环境污染问题。本文介绍了铝/水反应可控制氢的原理、反应机理、制氢方法及制氢装置的最新研究进展,并讨论了研发中需解决的问题。铝/水反应制氢的关键在于破坏或抑制铝表面固有的或原位再生的致密钝化膜。该制氢系统的实际应用需具备快速的反应动力学,而制氢装置的设计应综合考虑反应热的利用、燃料电池产生的水循环利用、燃料盒和膜分离技术的应用,使用回收的废铝将降低其生产成本,实现铝基制氢系统的商业化应用。     

脱铝丝光沸石的吸附性能研究

丝光沸石是优良的吸附剂和工业生产对二甲苯的实用催化剂。脱铝是使丝光沸石改性的有效方法。Chen报道了脱铝丝光沸石对环己烷的吸附量在硅铝比为15～50范围内随硅铝比增加而减少,而在50～90范围内变化很小。张红浪等用高温水蒸气处理结合酸洗的方法脱铝,得到不同硅铝比的丝光沸石,并研究了脱铝对其结构、酸性和催化性能的影响。本     

Analysis of Toxic Aluminium Species in Natural Waters

Aluminium is known to be toxic to a wide range of aquatic organisms under certain conditions. Monomeric hydroxy ions have been found to be primarily responsible for aluminium aquatic toxicity.A survey of aluminium toxicity and a brief discussion of speciation schemes are presented. The fast reaction of Al³⁺ with pyrocatechol violet (PCV) followed by spectrophotometric analysis is a frequently used method for aluminium speciation. By using a flow system, one obtains fairly exact and reproducible control of the reaction time, and as a result it provides a direct method of analysis for free aluminium (including inorganic monomeric aluminium).The PCV-method has been adapted for the determination of aluminium in carbonate-rich natural waters using an improved buffering system. Thus it is possible to monitor aluminium concentrations in lake water as well as in pore water of the sediments of eutrophicated hardwater lakes that has been treated with aluminium salts as a restoration measure.     

Characteristics of CuAl<Subscript>2</Subscript>-Cu<Subscript>9</Subscript>Al<Subscript>4</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> nanocomposites synthesized by mechanical treatment

Summary Reactive milling of Cu-hydroxycarbonate - powder aluminium mixture brings many complex chemical reactions such as decomposition, aluminothermic reduction and mechanical alloying resulting in the formation of nanometer size composites that contain intermetallic phases, -Cu₉Al₄ and -CuAl₂, with aluminium oxide.     

Thermal decomposition of sodium aluminium sulphate crystallohydrate

Dynamic TG investigations were carried out to elucidate the mechanism of thermal decomposition of aluminium sodium sulphate crystallohydrate. Shimadzu 31H and MOM Derivatograph X-ray diffraction and other techniques were used to determine data on the decomposition, activation energy, structure and phases in the solid products. Isothermal study in the temperature ranges 883–958 K and 983–1113 K in air or a reducing gas atmosphere revealed different reaction mechanisms. Depending on the experimental conditions, mainly Al₂O₃ can be obtained.     

Formation of YAG from coprecipitated yttrium aluminium hydroxides

Thermal decomposition of the amorphous coprecipitate of yttrium and aluminium hydroxides forming yttrium aluminium garnet has been investigated employing thermal analyses, X-ray diffraction and IR spectroscopy. On heating, the coprecipitate progressively loses water forming a stable but highly disordered hydroxy garnet which crystallizes at 1180 K and decomposes to YAG at 1290 K. Nucleation of the crystalline phase appears to begin at 800 K.The authors thank Dr. P. V. Ravindran of the Analytical Chemistry and Shri N. K. Kulkarni of the Fuel Chemistry Divisions of BARC for their assistance in the thermoanalytical experiments.     

Thermal transformations of the products of partial hydrolysis of hydrous aluminium nitrate

Thermal analysis, mass spectrometry, infrared spectrophotometry, X-ray phase analysis, scanning electron microscopy, and sorption methods were used in the study of thermal transformations of the products of partial hydrolysis of hydrous aluminium nitrate in ammonia medium. It has been found that the process of aluminium nitrate hydrolysis under the conditions applied and in the presence of ammonia gives boehmite as the main product, with some admixture of a basic salt.Aluminium oxide obtained from the products of partial hydrolysis of hydrous aluminium nitrate in ammonia medium at 550°C has a crystalline -Al₂O₃ structure. Its specific surface, as determined by low-temperature adsorption of nitrogen, exceeds 200 m²g^–1. Features of the products are well developed mesopore structure and considerable ability of benzene adsorption. Calcination of the obtained aluminium oxide for 2 h at 900°C reduces its specific surface to about 110 m² g^–1.This revised version was published online in November 2005 with corrections to the Cover Date.     

Direct complexometric determination of aluminium in "alzinoy"

A simple and precise method for the complexometric determination of aluminium in "Alzinoy" (a binary alloy of aluminium and zinc) is described. After dissolution of the sample in hydrochloric acid, aluminium, zinc and any lead and iron are complexed with excess of EDTA. The excess of EDTA is titrated with lead solution, with Xylenol Orange as indicator. Ammonium fluoride is then added to decompose the Al-EDTA complex, and the EDTA liberated is titrated with lead solution. Four samples can be analysed in about 45 min.     

Attachment of Polymer Films to Aluminium Surfaces by Photochemically Active Monolayers of Phosphonic Acids

Summary: We describe a simple photochemical process that allows the covalent attachment of a variety of different polymers at room temperature onto aluminium surfaces. The system is based on a photoreactive benzophenone derivative that is bound to aluminium surfaces by a phosphonic acid anchor. The synthesis of the phosphonic acid is described and the immobilization of this compound is studied by X‐ray photoelectron and FT‐IR spectroscopy. After deposition of the polymeric coating, UV light illumination at 365 nm, and solvent extraction of the substrate, polymer monolayers are obtained that are chemically bound to the surface.

Covalent attachment of polymers to the aluminium‐bound benzophenone phosphonic acid.     

Aluminium speciation: Clinical and environmental aspects

The speciation of aluminium in serum and in water is discussed. Ultramicrofiltration and HPLC techniques have been used to show that > 90% of the aluminium in serum is non-ultrafiltrable and bound to the protein transferrin. Regarding the toxicity and speciation of aluminium in natural waters the literature is plagued by disparities. The present lack of designed protocols and reference waters for the determination of the toxic aluminium species is thought to play a key role in producing these disagreements.     

Electron Rutherford back‐scattering case study: oxidation and ion implantation of aluminium foil

Electron Rutherford back scattering (ERBS) is a new spectroscopy for determining the composition of surfaces. In this work the surface sensitivity of ERBS was investigated by changing the entrance and exit angle of the electron beam while keeping the scattering angle constant. It was found that in this way the surface sensitivity of the technique can be varied considerably. We use aluminium as a test case for ERBS, as it is well studied. The technique has been used to investigate the oxide film of aluminium foil as manufactured and the native oxide (Al₂O₃) film formed on a clean aluminium surface exposed to air. We have also used ERBS to investigate the presence of Xe, implanted during the sputter cleaning process, at a variety of depths within an aluminium matrix. Copyright © 2007 John Wiley & Sons, Ltd.     

The influence of aluminium and aluminium oxide on the effects of mechanical activation of nickel hydroxocarbonate

The chemical and physical processes occurring during the grinding of nickel hydroxocarbonate and mixtures of nickel hydroxocarbonate with aluminium and aluminium oxide were discussed. For mechanical treatment a planetary ball mill was used. The phase analyses of ground products were carried out using thermogravimetry and X-ray diffraction methods. The amount of Ni₂(OH)₂CO₃ undecomposed and Al₂O₃xH₂O, xNiO, Ni⁰, Ni_xAl_y alloys and remained Al⁰ in the systems strongly depends on the proportion of components and on the duration of grinding in a mill which was used in the study. The comparative results are presented.This revised version was published online in November 2005 with corrections to the Cover Date.