MATERIALS TESTE pyrite

In all of the functional group tests of kerogen, the inorganic material removed from the oil shale by attrition grinding was used as a mineral blank. Because pyrite was concentrated with the kerogen and was not separated with the mineral, pyrite equivalent to that present in the kerogen concentrate was added to the mineral blank. 

The notion that naturally occurring organic polysulfides in coal decompose to form elemental sulfur has also been tested in another way. Buchanan and his associates have shown that the 32S/34S ratios of the elemental sulfur and the pyrite in another Illinois Basin Coal Sample Program coal are similar and different from the 32S/34S ratio for the organic material in the same coal (Buchanan, D., private communication, 1989). This result infers that pyrite is the source of elemental sulfur. Thus, we conclude that oxidative chemical and bacteriological processes convert pyrite to elemental sulfur when pristine coals are exposed to the atmosphere. 

Analytical Procedures. The samples of bituminous coals were analyzed for pyritic sulfur, sulfate sulfur and total sulfur using conventional wet chemical procedures adapted from the American Society of Testing Materials (23, 24). The ASTM D 3177-75, The Eschka method was used for the total sulfur, and ASTM D-2492-79was used for sulfate and pyritic sulfur determinations. The treated samples were filtered through a Whatman 2 filter paper to separate the coal particles from the liquid medium. The filtered sample was washed with 0.1 N HCl followed by distilled water to remove traces of absorbed sulfate and iron. 

First, the question of where nucleotide monomers may have come from is critical. Given that the formose reaction is the most likely candidate for the synthesis of prebiotic ribose, but yields very little pure material, the role of stereoselective catalysts (clays, amino acids, or lipid aggregates) in directing the reaction should be fully explored. In this respect, Wachters-hauser16 has advanced a scheme for nucleotide synthesis based on pyrite catalysis than can be readily tested. 

Generally, (1) the rate of oxidation of pyrite increases with the exposed, that is, available, pyrite surface the coal must be in a finely divided state to expose a maximum of the embedded pyrite. (2) F. ferrooxidans can accelerate the oxidation of diverse pyritic materials and coarsely crystalline marcasite, but not the oxidation of coarsely crystalline pyrite. (3) Thiobacillus thioox-idans does not enhance the oxidation of the experimental materials, with the possible exception of marcasite this organism appears to play no role in pyrite oxidation. (4) Lattice imperfections or the presence of some impurity in the mineral affects the ability of the test organisms to accelerate oxidation—coarsely crystalline pyrite proved resistant to oxidation, whereas coarsely crystalline marcasite and pyrite concretions and concentrates from coal were oxidizable (Silverman et al., 1961). 

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