PubMed · 600111
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B M Vaĭnshteĭn. [Hydrogen sulfide oxidation by thionic bacteria].. https://pubmed.ncbi.nlm.nih.gov/600111/
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To improve the sulfur removing capacity of the conventional Zn-Ti-based H2S removal sorbents, a new Zn-Ti based sorbent (ZT-cp) was prepared by the coprecipitation method and tested in a packed bed reactor at middle temperature conditions (H2S absorption at 480 degrees C, regeneration at 580 degrees C). The new Zn-Ti-based sorbent showed excellent sulfur removing capacity without deactivation, even after 10 cycles of absorption and regeneration. The conventional Zn-Ti-based sorbents (ZT-700, ZT-1000), however, that were prepared by physical mixing, were continuously deactivated. In particular, the initial sulfur removing capacity of the ZT-cp sorbent showed a very high absorption value (0.22 g S/g sorbent), which corresponded to 91.6% of theoretical absorption amount. These results can be explained by the difference in physical properties such as pore volume, surface area, and particle size. It was also found that the sulfides formed from the ZT-cp and ZT-1000 sorbents with spinel structure were easily regenerated even at 580 degrees C. Those from the ZT-700 sorbent, with separated ZnO and TiO2 structures, needed a temperature higher than 610 degrees C for regeneration.
Accumulation of sulfur-containing compounds and their bacterial mediated reductions have led to the emission of pungent odors from stagnant water bodies. This study is focused on the contribution of inorganic sulfur compounds in the emission of hydrogen sulfide. The measured dissolved oxygen levels have demonstrated good negative correlations with the dissolved sulfide levels implying the oxygen deficiency is the key for the reduction of sulfate ion and sulfite ion to sulfide ion. Particularly, the dissolved molar fractions of sulfide from the total dissolved sulfur compounds (sulfates, sulfites and sulfides) have a very good correlation with the dissolved oxygen for the stagnant water bodies except the artificially aerated prawn farms. For the stagnant water bodies with significant correlations, linear regressions are reported for them to be utilized in estimating one component of the regression from the measurement of the other. The measured data were further utilized to estimate the levels of hydrogen sulfide gas. The pH of the water bodies has confined much of the dissolved sulfides in the form of bisulfide ion and they can be easily escaped to the atmosphere upon acidification due to industrial discharges and/or acidic precipitations. The estimated levels of hydrogen sulfide just above the water surface were plotted for the most polluted stagnant water body in Sri Lanka for the pH range of 5-10 and temperature range of 25-35 degrees C.
In Japan, it is required to measure the hydrogen sulfide (H2S) concentration before sewerage work can commence, in order to prevent toxic accidents caused by H2S. The actual H2S concentration of the sewerage hole is often different from that initially measured, and there is often a more than fatal concentration because of rapidly volatilizing H2S. However, no countermeasures for this have been developed, nor has any system for the measurement of the H2S held in sewerage water and sludge been established yet. In this paper, therefore, the measurement of H2S dissolved in water was investigated, and the actual form of the H2S held in the water and the sludge was analyzed. Prevention measures against toxic accidents were also investigated. Water and sludge were collected from an actual sewerage hole, and the quantities of H2S held in them were measured by the new method with the stripping which we developed. We also determined the quantity of H2S volatilized from the water surface during work, and estimated the change of air quantity necessary to reduce the concentration of H2S to a safety level for workers. As a result, it was shown that even if the H2S concentration of the gas phase before the work is regarded as at a safety level for workers, they may be in an extremely dangerous situation resulting from the rapid volatilization of H2S during their work.(ABSTRACT TRUNCATED AT 250 WORDS)