Partitioning aluminum

Aluminum occurs widely in nature in silicates such as micas and feldspars, complexed with sodium and fluorine as cryolite, and in bauxite rock, which is composed of hydrous aluminum oxides, aluminum hydroxides, and impurities such as free silica (Cotton and Wilkinson 1988). Because of its reactivity, aluminum is not found as a free metal in nature (Bodek et al. 1988). Aluminum exhibits only one oxidation state (+3) in its compounds and its behavior in the environment is strongly influenced by its coordination chemistry. Aluminum partitions between solid and liquid phases by reacting and complexing with water molecules and anions such as chloride, fluoride, sulfate, nitrate, phosphate, and negatively charged functional groups on humic materials and clay. 

Agee C. B. and Walker D. (1990) Aluminum partitioning between olivine and ultrabasic silicate liquid to 6 GPa. Contrib. Mineral. Petrol. 105, 243 -254. 

Chapter 3 through Chapter 8 deal with the basic aspects of the practical uses of PLC. Chapter 3 describes sorbent materials and precoated layers for normal or straight phase (adsorption) chromatography (silica gel and aluminum oxide 60) and partition chromatography (silica gel, aluminum oxide 150, and cellulose), and precoated layers for reversed-phase chromatography (RP-18 or C-18). Properties of the bulk sorbents and precoated layers, a survey of commercial products, and examples of substance classes that can be separated are given. 

Aluminum oxides, similar to silica gels, are available as bulk materials and as precoated plates, to be used not only for straight phase adsorption chromatography, but also for partition PLC (see Table 3.3 and Table 3.4). In particular, the aluminum oxide type 150 (i.e., mean pore diameter 150 A [15 tun]) is suitable for partition chromatographic purposes. 

Coprecipitation is a partitioning process whereby toxic heavy metals precipitate from the aqueous phase even if the equilibrium solubility has not been exceeded. This process occurs when heavy metals are incorporated into the structure of silicon, aluminum, and iron oxides when these latter compounds precipitate out of solution. Iron hydroxide collects more toxic heavy metals (chromium, nickel, arsenic, selenium, cadmium, and thorium) during precipitation than aluminum hydroxide.38 Coprecipitation is considered to effectively remove trace amounts of lead and chromium from solution in injected wastes at New Johnsonville, Tennessee.39 Coprecipitation with carbonate minerals may be an important mechanism for dealing with cobalt, lead, zinc, and cadmium. 

If the analysis reports the amount of ferric iron, this value is accepted and aluminum is partitioned between Vl-fold and IV-fold coordinated sites, according to... 

Whereas several specific soil attributes are advocated as being responsible for DOC sorption in the mineral soil (Table V), it appears that the greater the clay or aluminum and iron oxide content of a soil, the greater its adsorptive capacity for DOC. For example, there is a positive correlation between m (the measure of the affinity of a substance for the sorbent or the partition coefficient) and soil clay content, dithionite extractable iron (Fej), and oxalate extractable aluminum (Al0) (Moore et al., 1992 Nelson et al., 1993 Kaiser and Zech, 1998). Direct measurements of the surface area of soil particles also correlate very well with DOC adsorption capacity (Nelson et al., 1993). Furthermore, Nelson et al. (1993) report that riverine DOC concentrations are negatively correlated to the clay content of watershed... 

Indicates the pore space available for water and roots influenced by soil composition (mineral content, mineral type, and organic matter) and soil texture Affects adsorption of the chemical Affects the surface area where adsorption can take place Influences partitioning and availability of chemicals Affects ability of a soil to transmit water or air Dictates the porosity of the soil Affects the form, reactivity, solubility, availability, and toxicity of some contaminants Affects the toxicity of some substances (mainly heavy metals) with binding or antagonistic mechanisms, for example, by alkaline-earth metals and aluminum Organic matter content, type, and % carbon Influences soil sorption properties for heavy metals and... 

The aqueous process portion of this paper describes attempts to improve the recovery of americium. The first part deals with modifications to the cation exchange step the second describes development of a solvent extraction process that will recover americium from residues containing aluminum as well as other common impurities. (The anion exchange process cannot partition americium and aluminum.) Results of laboratory work are described. 

Partition Chromatography. Unlike the other types of chromatography discussed thus far, this type is usually used for analytical (rather than preparative) applications. In addition, this type of chromatography is often performed in a thin-layer (rather than a column) format. The stationary phase in partition chromatography is usually a glass plate (rigid) or polyester sheet (flexible) coated with a very thin layer of the desired adsorbent. For most applications, the adsorbent is a cellulose, silica, polyamine, or aluminum oxide-based matrix. In... 

Partitioning and mobility of metal ions, metal complexes, and ligands in soils or sediments are affected by their adsorption onto a variety of substrates. As mentioned earlier (see Section 6.3.1), natural oxides offer suitable adsorption sites for some of these species and may even undergo dissolution as a result. Here, an understanding of the bonding phenomena is crucial. For example, the adsorption of [Co(III)EDTA] (here written as [ML]-) on hydrated aluminum oxide surfaces (written as =A10H) can be represented as ... 

Trioctahedral micas, such as phlogopite or biotite, are characterized by four distinct cation lattice sites tetrahedral (Z) sites occupied by silicon and aluminum octahedral (Y) sites, denoted Ml and M2, occupied by Al, Cr, Fe +, Ti, Fe +, Mg, and Mn and a large 12-fold coordinated interlayer X-site occupied by potassium, sodium, calcium, and other large cations. The low partition coefficients for lanthanides, uranium and thorium in phlogopite (<2X 10 ) indicate, however, that large highly charged cations cannot... 

The lower mantle is made predominantly of magnesium perovskite, and thus a solid understanding of element partitioning between perovskite and silicate melt is relevant to the early history of the Earth. Much of the early work with perovskite was done on aluminum-free or low-aluminum materials. However, magnesium perovskite can accommodate AI2O3 into its structure (Wood, 2000 Stebbins et ai, 2001),... 

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