Aluminium speciation

Figure 4.10 — Flow-through sensor for aluminium speciation coupled to an FI manifold for implementation of the Driscoll method. SV switching valve IV...

Prokisch et al. [85] described a simple method for determining chromium speciation in soils. Separation of different chromium species was accomplished by the use of acidic activated aluminium oxide. Polarographic methods have been applied in speciation studies on chromium(VI) in soil extracts [86]. Mi-lacic et al. [88] have reviewed methods for the determination of chromium(VI) in soils. 

Matthias, A., Maurer, M., and Parlar, H. (2003). Comparative aluminium speciation and quantification in soil solutions of two different forest ecosystems by 27A1NMR. Fresenius Environ. Bull. 12,1263-1275. 

Total concentration of aluminium in equilibrium with gibbsite. In the above calculation a total concentration may have been specified in which the solubility of a mineral phase may have been exceeded therefore, it would be appropriate to calculate the speciation and total aluminium in equilibrium with a specified mineral phase, e.g. gibbsite. 

In addition to the soluble chemical species and possible solid phase species described in the previous sections no discussion on speciation can be complete without the consideration of surface species. These include the inorganic and organic ions adsorbed on the surface of particles. Natural systems such as soils, sediments and waters abound with colloids such as the hydrous oxides of iron, aluminium, manganese and silicon which have the potential to form surface complexes with the various cationic and anionic dissolved species (Evans, 1989). 

Aluminium speciation in acidic stream water. It is often necessary to estimate the speci-... 

Oilman, L.-O. and Sjoberg, S. (1988) Thermodynamic calculations with special reference to the aqueous aluminium system. In Metal Speciation Theory, Analysis and Application (eds Kramer, J.R. and Allen, H.E.). Lewis Publishers, Chelsea, MI, pp. 1-40. 

Sjoberg, S. and Ohman, L.-O. (1985) Equilibrium and structural studies of silicon (IV) and aluminium (III) in aqueous solution. Part 13. A potentiometric and 27A1 nuclear magnetic resonance study of speciation and equilibria in the aluminium(III)-oxalic acid-hydroxide system.f. Chem. Soc. Dalton Trans., 12, 2665-2669. 

Berggren, D. (1989) Speciation of aluminium, cadmium, copper, and lead in humic soil solutions - a comparison of the ion exchange column procedure and equilibrium dialysis. Int.J. Environ. Anal. Chem., 35, 1-15. 

Direct methods for determining the combinational form of an element or its oxidation state include infrared absorption spectrometry, X-ray diffraction and, more recently, electron paramagnetic resonance - nuclear magnetic resonance -and Mossbauer spectrometry. With such techniques the combinational forms of major elements in soil components such as clay minerals, iron, manganese and aluminium oxyhydroxides and humic materials and the chemical structures of these soil components have been elucidated over the past 50 years. These direct, mainly non-destructive, methods for speciation are dealt with in some detail in Chapter 3 and are not further discussed here. 

Research has continued on the speciation of aluminium in water and in soil related particularly to the effects of acid precipitation. Species of particular concern are Alm, Al(OH)2+ and Al(OH)4. These species are the most toxic with regard to fish and plants. The presence of fluoride, sulfate and organic compounds that can form complexes with aluminium result in a lower degree of toxicity. Consequently, the objectives of a number of investigations have been the relationship of... 

Stabilities of lake and tap water samples for aluminium speciation were investigated (Fairman etal., 1994). Concentrations of 25-1000mgl 1 total aluminium in high-density polyethylene containers were stable for 30 days. Thereafter, increases in pH resulted in the precipitation of aluminium hydroxy species. 

Parker, D.R., Kinraide, T.B. and Zelazny, L.W. (1988a) Aluminium speciation and phytotoxicity in dilute hydroxy-aluminium solutions. Soil Sci. Soc. Am.J., 52, 538-544. 

Mitrovic, B., R. Milacic, B. Pihlar, and P. Simoncic. 1998. Speciation of trace amounts of aluminium in environmental samples by cation-exchange FPLC-ETAAS. Analysis 26 381-388. 

A. K. Flaten, W. Lund, Speciation of aluminium in tea infusions studied by size exclusion chromatography with detection by post-column reaction, Sci. Total Environ., 207 (1997), 21D28. 

Aluminium is an environmentally abundant element and has no known biological function in living cells. On the other hand, A1 exhibits biological toxicity as demonstrated in experimental models." " Intake and output of aluminium for the healthy population from various sources, biological monitoring of occupational aluminium exposure in serum and speciation analysis of the amount and composition of A1 species with high and low molecular masses, have been reviewed by several groups. Besides the use of mass spectrometric and non-mass spectrometric techniques (e.g., ETAAS after separation of human serum proteins ) ESI-MS-MS analysis has also been performed to identify the A1 species. 

Owen, L.M.W., Crews, H.M. and Massey, R.C., Aluminium in tea SEC-ICP-MS speciation studies of infusions and simulated gastro-intestinal digests. Chem. Spec. Bioavail., 4(3) (1992) 89-96. 

Many of the important chemical reactions controlling arsenic partitioning between solid and liquid phases in aquifers occur at particle-water interfaces. Several spectroscopic methods exist to monitor the electronic, vibrational, and other properties of atoms or molecules localized in the interfacial region. These methods provide information on valence, local coordination, protonation, and other properties that is difficult to obtain by other means. This chapter synthesizes recent infrared, x-ray photoelectron, and x-ray absorption spectroscopic studies of arsenic speciation in natural and synthetic solid phases. The local coordination of arsenic in sulfide minerals, in arsenate and arsenite precipitates, in secondary sulfates and carbonates, adsorbed on iron, manganese, and aluminium hydrous oxides, and adsorbed on aluminosilicate clay minerals is summarized. The chapter concludes with a discussion of the implications of these studies (conducted primarily in model systems) for arsenic speciation in aquifer sediments. 

Figure 7 Speciation profiles in the anode vicinity in the case of aluminium...

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