Thermal aluminium compounds

To aid chemical uses, the separation of urushiol on cation exchange resins has been employed (ref. 320). Recent work has concentrated on the preparation of various salts from Al, Sb (ref.321), Ti (IV), Fe(ll) and Cu(ll) (ref. 322). Aluminium compounds possessed good thermal stability, antimony compounds flame-retardant properties and titanium componds excellent anticorrosion action. 2 1 Complexes... 

Refs. 18, 113), and Zfiv 185,186 Aluminium compounds are of interest as possible precursors for the generation of catalytically active forms of AIF3 (cf Section 3.1) by thermal decomposition. Iron and manganese compounds are of interest because of their low-dimensional magnetic properties (see Section 4.1). 

Due to the very high gas temperature, long residence times, and inert atmosphere in the plasma, chemical interferences caused by the formation of thermally stable compounds or radicals are unlikely, especially in ICPs. For example, the interferences caused by phosphate and aluminium in the determination of calcium appear in combustion flames, DCPs, CMPs, and MIPs, but not in conventional ICPs. However, with low power ICPs these effects might exist to some extent. In general, with increased plasma power, chemical interferences become smaller. 

Table b.1-ir2 Linear thermal expansion coefficient a of aluminium compounds... 

When nitrobenzene is in the presence of aluminium chloride at a temperature greater than 90 C the mixture obtained is thermally unstable. Its decomposition is explosive pressure rises considerably and in a very short period of time. The following reaction that leads to the formation of very unstable compounds has been identified ... 

Aluminium hydroxide is essentially non-toxic, but does require high addition levels to be effective. As a result, the physical properties of the compound usually suffer. Its fire retardancy action results from the endothermic reaction which releases water under fire conditions and produces a protective char . The endothermic reaction draws heat from the rubber/filler mass and thus reduces the thermal decomposition rate. The water release dilutes the available fuel supply, cooling the rubber surface and mass. 

In the earliest days of flame AAS, air-propane and air-butane flames were often used to atomize samples, largely because they had a reputation for being simple and safe in operation. However it was soon found that such flames were not satisfactory for breaking up many thermally stable chemical compounds into the free atoms required to obtain atomic absorption. If samples and standards are not atomized to the same extent, erroneous results are obtained. Nowadays the most commonly used flame is the air-acetylene flame. This flame is safe and relatively inexpensive to use, and sufficiently hot at ca. 2200 °C to atomize molecules of many common elements. However it is not sufficiently hot to break the element-oxygen bonds of some elements, the so-called refractory oxide-forming elements. These include, for example, aluminium and silicon. Such determinants require a hotter flame. Also atomization efficiency of some elements may be influenced by matrix elements and ions. For example, phosphate or aluminium depress the atomic absorption signals of calcium in an air-acetylene flame. Thus there is a need for a safe, inexpensive and reliable higher temperature flame in AAS. 

It was shown in [18] that practically monophase fine barium hexaaluminate can be obtained by mechanical activation of a mixture of barium oxide with Y-AI2O3, which exhibits acid properties to a larger extent than a-Al203, and by consequent thermal treatments at increased temperature. The product then is grinded in the presence of water. The synthesis was shown to proceed almost completely after activation for 5 min in the AGO-2 planetary mill and thermal treatment at 1300°C for 1 h. Mechanical activation of the mixture of aluminium hydroxide with barium oxide, followed by thermal treatment at 900°C, results in the formation of the final product and a-Al203 as an admixture which remains even at 1300°C. Mechanochemical synthesis helped also to synthesize barinm hexaaluminate in which a part of aluminium cations is replaced with manganese, iron, cobalt cations. Such compounds are nsed as active ceramics in catalysis [17]. 

Cordierite synthesis method based on mechanical activation of mixtures of hydrated oxides of calcium, aluminium and silicon, as well as natural hydrated compounds (talc, kaolinite and gibbsite), has been developed in [2, 3]. Mechanical activation of these mixtures does not lead to the formation of new phases but provides good mixing at the cluster level giving aggregates that form cordierite during the subsequent thermal treatment. 

Warm the air up (by absorbing solar radiation and thermal-lR radiation) black carbon, iron, and aluminium, polycyclic and nitrated aromatic compounds. 

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