Mineral matrices

Furthermore, specific mineral matrices for use in conditioning separated radio nuclides are also elaborated and studied on the basis of mineral structures, known in nature for their selective-insertion capabihties with respect to certain radio nuclides and their stabihty over time. Among those phases, hollandite, zirconoUte, apatite and monazite are particularly studied. 

Certain manganese porphyrins adsorbed on silica or alumina, or intercalated in different mineral matrices such as montmorillonite, are also very efficient in alkane hydroxylation.150 151 Alcohol yields and alcohol ketone ratios are remarkably higher than those obtained with the corresponding soluble manganese porphyrins. Manganese tetra(4-Al-methylpyridiniumyl)porphyrin supported on montmorillonite, for instance, is efficient in the hydroxylation of compounds of low reactivity such as n-pentane and n-heptane.151... 

At the end of this section dealing with the question What are carbonaceous chondrites and before trying to answer the question Where do they come from and what is their age , it seems necessary to emphasise the fact that the carbon present in the Cl and CM and to a lesser extent in the CO and CV chondrites exists as elemental carbon (Cl, CM, CO, CV), organic molecules (Cl and CM) and an ill-defined macromolecular compound (Cl, CM, CO, CV). The exact composition of this complex mixture will be discussed below. The only point that we would like to stress in this section is that organic matter is always found intimately mixed with mineral matrices. 

It is important to realise that a large portion of the potentially soluble organic matter is extractable only after demineralisation. This observation proves that low molecular-weight organic matter is trapped in mineral matrices probably in interlayer sites or at grain boundaries. The hydration of silicates and the synthesis of non-maeromoleeular organic matter were probably two strongly interrelated processes. 

It has been suggested [95] that the synthesis of structured porphyrins with controllable steric ambience is a strategic direction in the reproduction of enzyme protein cavities, which control the selectivity and stability of biochemical reactions such as cytochrome P-450. Such an approach to the synthesis of biomimics has considerable potential, especially in their application on mineral matrices silicon dioxide, alumina and zeolites. Data exist on the synthesis of a biomimic [96] with a complex porphyrin complex (5-pentafluorophenyl-10,15,20-tri(2,6-dichlorophenyl)porphyrin (FeMPFDCPP)) covalently linked to aminopropyl silicon dioxide, which is applied in oxidation of ds-cyclooctene, cyclohexene, cyclohexane and adamantane with participation of iodosylbenzene dissolved in dichloromethane. 

Barloy, L., Lallier, J. P., Battioni, P., Mansuy, D., Piffard, Y Tournous, M., Yalim, J. B. and Jones, W. (1992). Manganese porphyrins adsorbed or intercalated in different mineral matrices - preparation and compared properties as catalyst for alkene and alkane oxidation. New J. Chem. 16, 71. 

Figure 4. Relative yields of acetate for (72 h) hydrous pyrolysis experiments with three terrestrial mudrocks of identical thermal rank and similar mineral matrices. (Reproduced with permission from Ref. 14. Copyright 1987 Pergamon Journals).

Bioleaching processes use microorganisms to solubilize heavy metals or heavy-metal oxides from mineral matrices by biological catalyzed oxidation-rednction processes. In both soil washing or bioleaching processes, the elnted heavy metal ions are then removed from the aqueous stream by the various chemical or biological process technologies (see details in Rorrer, 1999). 

Laurencin CT, Attawia MA, Elgendy HE, Herbert KM (1996) Tissue engineered bone-regeneration using degradable polymers The formation of mineralized matrices. Bone 19 S93-S99 Laurencin CT, Ambrosio AMA, Borden MD, Cooper JA (1999) Tissue engineering Orthopaedic applications. Ann Rev Biomed Eng 1 19-46... 

R 106 N. Nestle, NMR Studies on Heavy Metal Immobilization in Biosorbents and Mineral Matrices , p. 215... 

Inorganic mineral matrices are often the major bulk constituent (>90 wt%) of soils and sediments, and these may in some cases play important roles in equilibria and rates of HOC sorption. Schwarzenbach and Westall (30) have shown that exposed external and internal pore surfaces of inorganic mineral domains contribute significantly to equilibrium sorption of HOCs if a soil or sediment has a low value (e.g., < 0.001). It is widely believed that the diffusion of HOC molecules into meso- (pore diameter = 20-500 A) and micropores (pore diameter < 20 A) is very slow, and thus responsible for the overall slow rates of sorption typically exhibited by soils and sediments. 

Eigure 9.4 presents the emission lines of the Dq Fi transition revealing two kind of environment in Eu -doped complex nuclear borosilicate glass. There are attributed to (1) a borate environment and (2) a silicate (me, by compariscm of the ligand field parameters B2 with referenced glassy matrices (Ollier et al. 2002). Eurthermore, specific mineral matrices for use in conditioning separated radio nuclides are also elaborated and studied on the basis of mineral structures, known in nature for their selective-insertion capabilities with respect to certain radio nuclides and their stability over time. Among those phases, hollandite, zirconolite, apatite and monazite are particularly studied. 

Shale-normalized data from a 255 m sample illustrate the major features observed by Sholkovitz et al. (1994) (fig. 16). Included in this comparison is the lanthanide composition of dust collected in Bermuda within a few months of the water sample collection (Sholkovitz et al. 1993). The major observation is that surface coatings have a lanthanide composition which is distinct from that of seawater, dust and the two mineral phases of the suspended particles. The mineral matrix of suspended particles and the atmospheric dust are similar in composition. Both mineral matrices have crustlike patterns indicating a detrital source from the atmosphere. About 40-70% of the lanthanides are contained in the acetic acid digest the strong acid digest carries 10-30% and the bomb digest carries 15-25%. At the heavy end of the series (Yb and Lu) the three fractions contribute equal proportions. These observations indicate that the surface... 

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