Sulphur species

Carlson et al. (1999b) compared laboratory spectra and Galileo data and suggested that hydrated sulphuric acid is the main component in the dark surface material, which probably also contains sulphur polymers modified by radiation chemistry. A sulphur cycle involving three sulphur species is suggested sulphuric acid (H2SO4), sulphur dioxide (SO2) and sulphur polymers (S ). 

Boye K, Almkvist G, Nilsson SI, Eriksen J, Persson I. Quantification of chemical sulphur species in bulk soil and organic sulphur fractions by S K-edge XANES spectroscopy. Eur. J. Soil Sci. 2011 62 874-881. 

Alternative oxidation reactions may lead to the production of oxy-sulphur species 2MS + 7H20==2M(0H)2 + 8203 +... 

In the light of Eq. (2-7), the potential of surface oxidation of sulphide minerals to form elemental sulphur or oxy-sulphur species could be calculated. 

Unlike the specifically bound metals which participate in reversible redox reactions extraneously bound transition metals are well able to induce uncontrolled oxidation of sulphur containing ligands The so called metal driven Haber Weiss reaction is responsible for the formation of oxidised sulphur species leading to sulphonic acid. For example ... 

The 0 radical is well able to oxidise all sorts of sulphur species up to S(VI). 

It may appear rather strange to measure a strictly inorganic compound. However, there is one important correlation to biopolymers. In proteins the polypeptide chain imposes considerable strain on metal-sulphur binding centres which may lead to sulphur radical species. Such species have been discussed for cytochrome c oxidase and plastocyanin Likewise the polysilicates could take over the same role. They are capable to polarize the sulphur species and the existence of sulphur radicals are debated. 

The power of XPS-spectroscopy must be seen in the fast and efficient control of the homogeneity of an isolated protein. Commercial samples are sometimes not homogeneous enough or tend to show age dependent deterioration. These can readily be seen by XPS. When rapid and thorough isolation of a protein can be accomplished, no oxidised sulphur species are seen. A good example proved to be Cd, Zn-thionein which had no active redox metals. 

The cysteine rich Zn, Cd-thionein displays one homogeneous thiolate sulphur signal at 161.7 eV. Virtually no higher oxidation state of the sulphur is seen. Upon treatment with excessive H2O2, sulphonic acid is the exclusive detectable sulphur species at 167.4 eV (Fig. 4). 

Fouillac, C., Fouillac, A. M. Criaud, A. 1990. Sulphur and oxygen isotopes of dissolved sulphur species in formation waters from the Dogger geothermal aquifer, Paris Basin, France. Applied Geochemistry, 5, 415-427. 

Anderson RF, Vojnovic B, Patel KB, Michael BD (1986) Reaction of alcohol radicals with cyclic disulfides. An optical and conductometric pulse radiolysis study. Radiat Phys Chem 28 219-222 Anklam E, Margaretha P (1989) Organic sulfuranyl radicals. Res Chem Intermed 11 127-155 Armstrong D (1990) Applications of pulse radiolysis for the study of short-lived sulphur species. In Chatgilialoglu C, Asmus K-D (eds) Sulfur-centered reactive intermediates in chemistry and biology. Plenum, New York, pp 121-134... 

The proton exchange membrane has to be improved so as to reduce resistance across the membrane and the transfer of sulphur species across the membrane that results in the deposition of sulphur on the cathode thereby poisoning the cathode. The focus will initially be on testing membranes developed for fuel cells. The NWU will be acquiring and testing fuel cell membranes which include the three top membranes in meeting the minimum requirements as set by US DOE for 2008, from Professor P. Pintauro (Vanderbilt University, Nashville, USA), Dr. R. Wycisk (Case Western Reserve University, Cleveland, USA) and Giner Electrochemical Systems Inc. 

The best way to remove sulphur compounds is to convert the organic sulphur species to H2S over a hydrodesulphurization catalyst. The next step is sulphur removal with an absorbent. The same catalyst can usually convert any organo-chloride species to give HC1 and also act as an absorbent for most problematic metal species. A second absorbent is used for chloride removal70. 

If extra purification is needed to protect and extend the life of nickel-based, pre-forming and steam-reforming catalysts or precious metal-based catalysts, an ultra-purification absorbent may be used. This absorbent can be installed below the ZnO-based, H2S removal absorbent. It removes more H2S and organo-sulphur species so that the feed stream contains very low, parts-per-billion levels of sulphur70. 

Volkov II, Rozanov AG, Demidova TP (1992) Reduced inorganic sulphur species and dissolved manganese in the water of the Black Sea. In Vinogradov ME (ed) Winter state of the ecosystem of the open part of the Black Sea, Shirshov Institute of Oceanology RAS, Moscow, p 38 (in Russian)... 

While analyzing chemical processes in the Black Sea, the general features of the vertical structure and variability of the principal ingredients were considered. The analysis involved the distributions of the main parameters of dissolved oxygen, nutrients, sulphur species, metals, etc. In so doing, the redox layer was in the focus of our attention. The analysis was based on the use of the recent observation data of 1997-2006. 

Donato, P, de, C. Mustin, R. Benoit, and R. Erre. 1993. Spatial distribution of iron and sulphur species on the surface of pyrite. Appl. Surf. Sci. 68 81-93. 

Murray R C, 1983, Thermodynamics of Aqueous Sulphur Species. Journal of the Electrochemical Society, 130(7), 866-869. 

Equilibrium concentrations of gas phase SO2 and dissolved sulphur species in the same oxidation state (SO2, HSO s) are reached in a few seconds for droplets smaller than 100 pm diameter. However, for the time scales involved in rainout, oxidation of S(IV) to S(VI) dominates this mechanism for the accumulation of S by cloud droplets. The oxidation may proceed through the variety of mechanisms previously described ranging from catalytic reactions in solution often assisted by the presence of NHj,... 

We have made both field and laboratory measurments of the emission of CH4 and CO2 from both higher and lower termite families (Macro-termes, mound building species, Cubitermes, soil feeders, Trinervitermes, Reticulitermes, lower termites, and Gnathermitermes). Similarly, we have made laboratory measurements of the emission of CH4, CO2, CO, H2, C2 to Cio hydrocarbons, and reduced sulphur species from Reticulitermes and Gnathermitermes species. In addition, emissions from arboreal nests of an unidentified species of Nasutitermitinae were sampled in the field in Guatemala and analyzed for CH4 and C2 to Cio hydrocarbons [9]. 

Savoie, D.L., Prospero, J.M., Larsen, R.J., Huang, F., Izaguirre, M.A., Huang, T., Snowden, T.H., Custals, L. and Sanderson, C.G., Nitrogen and sulphur species in Antarctic aerosols at Mawson, Palmer Station, March (King George Island). J. Atmos. Chem., 17 (1993) 95-122. 

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