Sulfur analysis of Bolu-Mengen lignite before and after microbiological treatment using reductive pyrolysis and gas chromatography/mass spectrometry

Atmospheric pressure-temperature programmed reduction coupled with on-line mass spectrometry (AP-TPR/MS) is used for the first time on microbiologically treated coal samples as a technique to monitor the degree of desulfurization of the various sulfur functionalities. The experimental procedure enables the identification of both organic and inorganic sulfur species present in the coal matrix. A better insight in the degradation of the coal matrix and the accompanying processes during the AP-TPR experiment is obtained by a quantitative differentiation of the sulfur. The determination of the sulfur balance for the reductive pyrolysis gives an overview of the side reactions and their relative contribution in the total process. The volatile sulfur species are unambiguously identified using AP-TPR off-line coupled with gas chromatography/mass spectrometry (GC/MS). In this way, fundamental mechanisms and reactions that occur during the reductive pyrolysis could be quantified, explaining the differences in AP-TPR recoveries. Therefore, this study gives a clearer view on the possibilities and limitations of AP-TPR as a technique to monitor sulfur functionalities in coal

MECHANISM OF OXIDATION OF REDUCED SULPHUR COMPOUNDS BY THIOBACILLI

The mechanism of transport sulphur both outside and inside the cells was studied. Macroroentgen structural analysis and electronicmicroscopic researches showed that the membrane structures of thiobacilli carry out not only the oxidation function, but the transport function as well, which consists in the extraction of the formed sulphur from cell. This mechanism of sulphur deposition develops ac-— cording to the exocytosis type. The transport of elemental sulphur inside the cell involves the surface membrane structures (vesicles), while oxidation of the sulphur to sulphuric acid takes place on the outer surface of the cytoplasmic membrane. The vesicles are supposed also to participate in the primary dissolution of elemental sulphur at the site of contact of the cells with the mineral. The study of bacterial oxidation of sulphide minerals has shown the electrochemical nature of microbiological oxidation of sulphide minerals, which takes place at the level of its electronic structure. Pyrite with hole conductivity (with the cation deficit in composition) is oxidized by means of Thiobacillus ferrooxidans not only much more intensively, but also continuously as compared to pyrite with electron conductivity. Thiobacilli play a leading role in the oxidation of reduced sulphur compounds under natural conditions. The mechanism of this process however have not been studied sufficiently well so far. The main purpose of this work was to study the mechanism of sulphur transport, when sulphur was deposited or oxidized by thiobacilli, by means of cytological and cytochemical techniques. We believed that the mechanism,of sulphur transport either from, or into, the cell must be closely related to the submicroscopic organization of thiobacill