Coated particles hydroxide

The small (10 -lm) coating particles are typically aluminum oxide [1344-28-1/, Al O. These particles can have BET surface areas of 100 to 300 m /g. The thermal and physical properties of alumina crystalline phases vary according to the starting phase (aluminum hydroxide or hydrate) and thermal treatment (see ALUMINUM COMPOUNDS, ALUMINUM OXIDE). 

Sodium residues. Bottles containing sodium wire previously used for solvent drying constitute a fire and explosion hazard. The sodium, sometimes heavily coated with hydroxide or oxide film, should be covered with propan-2-ol and set aside with occasional swirling until all the sodium particles are destroyed (at least 2 hours). The contents of the bottle should then be poured into a large excess of water (water should not be added to the bottle) and the bottle washed out several times with industrial spirit. Only then can the bottle be safely rinsed with water. 

Concentrated dispersions have been prepared [158] of samples with relatively thick sihca shells around the gold cores (core diameter = 15 nm, total diameter =184 nm), and with the outer surface coated with 3-(trimethoxysilyl) propylmethacrylate (TPM). The TPM coated particles (which we denote Au—Si02-TPM) are slightly charged due to the presence of residual hydroxide ions on the silica surface [63], and the sols are stable in solvents... 

A significant fraction of lead carried by river water is expected to be in an undissolved form, which can consist of colloidal particles or larger undissolved particles of lead carbonate, lead oxide, lead hydroxide, or other lead compounds incorporated in other components of surface particulate matters from runoff. Lead may occur either as sorbed ions or surface coatings on sediment mineral particles, or it may be carried as a part of suspended living or nonliving organic matter in water. The ratio of lead in suspended solids to lead in dissolved form has been found to vary from 4 1 in rural streams to 27 1 in urban streams (Getzetal. 1977). 

Electron probe microscopy indicated that finer particles of oxide lead and silver were coated with ultra-fine slimes of Fe-hydroxide. 

Effects of Flooding and Redox Conditions onfs. I know of no published data on this. Bnt it is likely that the natnre of particle surfaces in intermittently flooded soils wonld restrict snrface mobility. For ions to diffuse freely on the surface there must be a continuous pathway of water molecules over the surface and uniform cation adsorption sites. But in intermittently flooded soils the surface typically contains discontinuous coatings of amorphous iron oxides on other clay minerals, and on flooding reduced iron is to a large extent re-precipitated as amorphons hydroxides and carbonates as discussed above, resulting in much microheterogeneity with adsorption sites with disparate cation affinities. 

Figure 1.1.19 illustrates such hematite particles coated with chromium hydroxide in which the latter was produced by the hydrolysis of a chrome alum solution in the presence of a-Fe203 cores on aging the dispersion at 85°C. For greater efficiency the chromium salt solution was either preheated or preheated with KOH (but avoiding precipitation of chromium hydroxide) (144). 

Fig. 9. The effect of magnesium hydroxide filler type on the dynamic storage modulus G of polypropylene (PP) at 200 °C (strain amplitude 10%, filler level 60% by weight). Magnesium hydroxide fillers differed in origin particle size and treatment. Mean particle size (pm) type A ( ), 7.7 type B (+), 0.9 type C ( ), 4.0 type D ( ), 0.53 type E, stearate-coated version of type A, (X), 3.7 unfilled PP (O) [36]...

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