Solid state speciation

Arai, Y., Lanzirotti, A., Sutton, S.R. et al. (2006) Spatial and temporal variability of arsenic solid-state speciation in historically lead arsenate contaminated soils. Environmental Science and Technology, 40(3), 673-79. 

Figure 7.2 Solid-state speciation in a crustal aerosol collected close to the Saharan Desert and an urban aerosol collected in the UK (Spokes et al., 1994). Results are expressed as a percentage of the total elemental concentration and obtained using a three stage sequential leach using the method of Chester et al. (1989). Stage one uses 1.0 M ammonium acetate to release loosely bound metals. Stage two involves addition of 1.0M hydroxylamine hydrochloride in 25% acetic acid to the residue to release metals held within the oxide and carbonate phases. Stage three uses nitric acid and hydrofluoric acid to break down the aluminosilicate lattice and release metals associated with the crustal fraction of the aerosol.

Quantitative chromium solid-state speciation in chromite ore processing residue (COPR) has defined the mineral species and the processes controlling the retention and release of Cr(VI) from CO PR-contaminated sites (Hillier et al, 2003). Information that, used within a process-based modelling framework, has helped to predict the impact of changes in physicochemical conditions on the COPR, to test the extent to which the system may be considered at equilibrium and that, therefore, need to be considered within the context of informed remediation (Geelhoed et al, 2001). 

Chester R., Thomas A., Lin F.-J., Basaham A. S. and Jacinto G. (1988) The solid state speciation of copper in surface water particulates and oceanic sediments. Mar. Chem. 24, 261-292. 

Nowadays, solid-state speciation or molecular identification of inorganic analytes is a hot topic in analytical chemistry. Molecular speciation allows individual components to be identified in mixtures, an impossible task for element or functional group detection methods. In fact, LMMS has been a forerunner in this field. Figure 3 illustrates the speciation scheme used in FT-LMMS. Basically, the miz difference between prominent signals from atomic ions and their adducts, the isotope patterns, and structural fragments such as oxide (adduct) ions in the case of oxysalts readily allow the molecular composition... 

Sodium-silicate glass, 151 Sol-gel films, 120, 173 Solid electrodes, 110 Solid state devices, 160 Solvents, 102 Speciation, 84 Spectroelectrochenristry, 40 Spherical electrode, 6, 8, 9, 61 Square-wave voltammetry, 72, 92 Staircase voltammetry, 74 Standard potential, 3 Standard rate constant, 12, 18 Stripping analysis, 75, 79, 110 Supporting electrolyte, 102 Surface-active agents, 79... 

Applications Table 8.58 shows the main fields of application of inorganic mass spectrometry. Mass-spectrometric techniques find wide application in inorganic analysis, and are being used for the determination of elemental concentrations and of isotopic abundances for speciation and surface characterisation for imaging and depth profiling. Solid-state mass spectrometry is usable as a quantitative method only after calibration by standard samples. 

From a structural point of view Bruno s hypothesis is sound. In chemical terms the hydrolysis proceeds with the formation of hydroxide bridges up to the formation of the trimer. Then at high concentrations trimeric units are fused together to form the higher aggregates, that can be seen as precursors to the structure adopted by Be(OH)2 in the solid state. (See Section IV, C, precipitation equilibria). Speciation diagrams for Bruno s model are shown in Fig. 3. Two points are noteworthy in these diagrams. In the first place the concentrations of the... 

As already stated, speciation is the characteristic distribution of various ionic and/or neutral species in an aqueous solution. Speciation calculation, allowing practical estimation of the reactive properties of an aqueous solution, acidity, redox state, the degree of saturation of the various solids, and so on, is carried out on a thermodynamic basis starting from the chemical composition of the solution of interest and using the reaction constants of the various equilibria of the type seen in equation 8.19. 

The use of these methods for speciation in solid materials requires that two essential assumptions—electrochemical reversibility and diffusive control—apply. Under these circumstances, theoretical CVs for ion-insertion solids are essentially identical to those for speeies in solution [206]. Since solid-state processes involve coupled... 

Very recent studies have examined the possibility of using 33S MAS spectroscopy in the study of some structural problems in cementitious materials107 108 and in sulphur speciation in silicate melts.109 Several processes of the deterioration of cements and more generally lapideous materials can be correlated to the stability of sulphate, to changes in the sulphate phase and to the interaction of sulphate ions with water molecules and hydrates.108 Since sulphate anion is one of the species that can be studied more easily by 33S NMR solid-state spectroscopy, this technique can be a valuable tool in studying... 

S solid-state MAS spectra at 19.6 T have been acquired for some bulk compounds representative of sulphate speciation in cement paste ettringite, [Ca6Al2(S04)3(0H)6 26H20],107,108 and three different samples of gypsum, [CaS04 -2H20].108 At 33S natural abundance, the acquisition of spectra with a... 

Nuzzio D. B. (2001) Sulfur speciation monitored in situ with solid state gold amalgam voltammetric microelectrodes polysulfides as a special case in sediments, microbial mats and hydrothermal vent waters. J. Environ. Monitor. 3, 61-66. 

Solid-phase speciation has been measured both by wet chemical extraction and, for arsenic, by instrumental methods principally X-ray absorption near edge structure spectroscopy (XANES) (Brown et al., 1999). La Force et al. (2000) used XANES and selective extractions to determine the likely speciation of arsenic in a wetland affected by mine wastes. They identified seasonal effects with As(El) and As(V) thought to be associated with carbonates in the summer, iron oxides in the autumn and winter, and silicates in the spring. Extended X-ray absorption fine stmcture spectroscopy (EXAES) has been used to determine the oxidation state of arsenic in arsenic-rich Californian mine wastes (Eoster et al., 1998b). Typical concentrations of arsenic in sods and sediments (arsenic <20 mg kg ) are often too low for EXAFS measurements, but as more powerful photon beams become available, the use of such techniques should increase. 

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