Volatile elements

Table 111. Elemental volatilization and transformation of chemical and physical properties in the fire environment.

The element volatilizes and it is condensed under water as white phosphorus. 

In several previous chapters, we have discussed element volatility. Here we focus on some of the most volatile constituents in meteorites - organic compounds, noble gases, and ices. Each of these actually constitutes a voluminous subject of its own in cosmochemistry, and we can only provide overviews of these interesting components. 

Nevertheless, we can make some general statements about the geochemistry of differentiated planets. The planetesimals from which they accreted had compositions determined largely by element volatility. Once assembled into a planet and heated, the partitioning of elements into cores and mantles was governed by their siderophile or lithophile affinities. Further differentiation of mantles to form crusts was controlled by the compatible or incompatible behavior of elements. 

The element volatilizes as a mix of neutral and singly charged positive atoms and perhaps is a pseudo-S-L process. 

In recent years predominantly continuous isothermal chromatography has been applied in gas chemical studies of transactinides. This technique offers the possibility to combine a continuous separation of volatile species with an in-situ detection of the products on the basis of single atom counting. To reach this ambitious goal, novel devices have been developed such as the On- Line Gas chemistry Apparatus (OLGA) [10] or, in a modified version, the Heavy Element Volatility Instrument (HEVI) [11] see also Chapter 4. 

Commercial production is by reduction of phosphate rock with coke and silica in an electric furnace. The element volatilizes and is condensed under water as white phosphorus, a soft, white, waxy solid (mp 44.1°C, bp 280°C) ... 

The bulk trace element abundance patterns in CAIs are generally agreed to reflect element volatility, with the most refractory elements enriched relative to solar (Cl chondrite) abundances, and volatile elements depleted. 

Figure 7 Siderophile element concentrations in averaged medium-Ti mare and terrestrial basalts, normalized to Cl chondrites. The elements are plotted in order of Cl-depletion factors in average medium-Ti mare basalt, but for some elements volatility may account in large part for the depletion. Data are from same sources as for Figure 6. To avoid an over-complex diagram, individual terrestrial compositions are not plotted, but all show similar patterns at the scale of this diagram the most noteworthy exceptions being low iridium (9 X 10 times Cl) and nickel (10 times Cl) in BCR-1, and relatively low osmium and iridium (virtually identical to mare basalts) and antimony (0.11 times Cl)...

During the combustion process, the low volatile trace elements tend to stay in the bottom ash or to be distributed between the bottom and fly ash. The more volatile trace elements (volatile and especially highly volatile trace elements) are vaporized in the furnace and they may be incorporated... 

Table 7 Char yields and elemental volatilization data for brominated polyester resins...

Resin Synergist (phr) Char yield Br Elemental volatilization Sn Zn Sh... 

All trace elements (volatile, non-volatile and intermediate) show the inverse concentration— particle size dependence, more pronounced in the material from runs with recirculation. One notable exception among the trace elements is Mn which shows a direct concentration—particle size dependence in the material from runs with recirculation and no dependence in the run without recirculation. 

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