Sodium-iron-sulfur system

Nguyen TB, Ermolenko L, Al-Mourabit A (2015) Sodium sulfide a sustainable solution for unbalanced redox condensation reaction between o-nitroanilines and alcohols catalyzed by an iron-sulfur system. Synthesis 47 1741-1748. doi 10.1055/s-0034-1380134 (Art ID ss-2014-c0749-st)... 

Among high-temperature batteries, the lithium-iron sulfide systems are reasonably safe, although there are some hazards connected with the 450-500°C operating temperature. The sodium-sulfur-system impact failure hazards are primarily connected with the possibility of SO2 emissions, sodium oxide dust, and fires resulting from sodium exposure to moisture. 

Nitrogenase is a complex enzyme which catalyzes the reduction of a variety of substrates (Table IV) with the concomitant hydrolysis of ATP. It contains two, easily separable, iron-sulfur proteins one of which contains molybdenum. These require a reductant, a reducible substrate, an ATP-generating system, and an anaerobic environment to function. The ATP-generating system is necessary because ADP inhibits nitrogenase activity. Two important discoveries have helped to simplify the assay for nitrogenase. First, sodium dithionite proved to be an adequate reductant to replace the complex and unstable pyruvate phosphoroclastic system (Bulen et al., 1965) and, second, nitrogenase reduces acetylene to ethylene (Dilworth, 1966 Schollhorn and Burris, 1967) which can be measured at nanomolar concen-... 

Onysko SJ, Kleinmann RLP, Erickson PM (1984) Ferrous iron oxidation by Thiobacillus ferroxo-dans inhibition with benzoic acid, sorbic acid, and sodium lauryl sulfate with benzoic acid, sorbic acid, and sodium lauryl sulfate. Appl Environ Microbiol 48 229-231 Osterloh F, Saak W, PoU S, Kroeckel M, Meier C, Trautwein AX (1998) Synthesis and characterization of neutral hexanuclear iron sulfur clusters containing stair-like [Fe6(u3-S)4(u2-SR)4] and nest-like [Fe6(u3-S)2(u2-S)2(u4-S)(u2-SR)4]. Inorg Chem 37 3581-3587 Palamo A, Femaddez-Jimenez A, Kovalchuk G, Ordonez LM, Naranjo MC (2007) Opc-fly ash cementitious systems study of gel binder produced during alkaline hydration. J Mater Sci 42 2958-2966... 

An example of a continuous aqueous dispersion process is shown in Figure 6 (24). A monomer mixture composed of acrylonitrile and up to 10% of a neutral comonomer, such as methyl acrylate or vinyl acetate, is fed continuously. Polymerization is initiated by feeding aqueous solutions of potassium persulfate (oxidizer), sulfur dioxide (reducing agent), ferrous iron (promoter), and sodium bicarbonate (buffering agent). Alternately the system may employ a sodium bisulflte/sulfur... 

Oxidation may be achieved in the presence of oxygen or air. Other suitable oxidants include sulfur, sodium polysulfide, iron (III) chloride, potassium ferro-cyanide (III) or potassium dichromate, peroxydisulfate or salts of aromatic nitro-sulfonic acids. An aqueous/alkaline medium is used in the presence of a high boiling organic solvent which is not miscible with water or which is almost immiscible with water. Cyclization with chlorosulfonic acid can be followed directly by oxidation with bromine to afford the thioindigo system, without separation of the intermediate. 

The major elements phosphorus and sulfur and the trace elements sodium, potassium, magnesium, calcium, chlorine, iodine, manganese, iron, cobalt, nickel, copper, and zinc, and a few others, play specific, critical roles in life. Several others occur in living systems but may not be essential for life. 

Among the elements that make up rocks and minerals, silicon, magnesium, and iron are of almost equal abundance followed by sulfur, aluminum, calcium, sodium, nickel, and chromium. Two of the most common minerals in meteorites and in the terrestrial planets are olivine ((Mg,Fe)2Si04) and pyroxene ((Mg,Fe,Ca)Si03). The composition obtained by averaging these two minerals is very similar to the bulk solar system composition, so it is really no surprise that they are so abundant. 

A battery system closely related to Na-S is the Na-metal chloride cell. The cell design is similar to Na-S however, iu addition to the /3-alumina electrolyte, the cell also employs a sodium chloroaluminate, NaAlCL . molten sail electrolyte. Tlie positive electrode active material consists of a transition metal chloride such as iron(II) chloride, FeCL, or nickel chloride, NiCty, in lieu of molten sulfur. This technology is in a younger state of development than the Na-S. 

A chemistry of cobalt-sulfide-thiolate molecular clusters comparable with that of iron systems has also begun to emerge. Treatment of [Co4( -SPh)6(SPh)4]2- with HS- in acetone affords the octanuclear cluster [Co8(ji4-S)6(SPh)8]4 isolated as its Pr4N+ salt.988 In MeCN solution the complex is red-purple with intense sulfur-core charge transfer bands which obscure the Co" d-d transitions. This behaviour contrasts with that of both mono- and poly-nuclear cobalt"-thiolate complexes, which all display LMCT bands below 440 nm and have well-developed v2 and v3 features. The [Co8(/j4-S6)]4+ core sustains reversible one-electron oxidation and reduction (E]l2 = —0.54, — 1.18 V, MeCN) and chemical reduction with sodium acenaphthylenide in THF gives [Co8(/r4-... 

The process of treating coal with CO2/water has been shown to remove as much as 15% of the ash. Ash removal apparently increases with increasing CO2 concentration in the system up to approximately 24g/L and is invariant with higher concentrations. It has been shown that, in addition to ash, sulfur is removed with treatment and that the volatiles content and heating value are unchanged. Specific ash elements which have been shown to be removed include silicon, aluminum, calcium, magnesium, sodium, and iron. The overall effect is a reduction in the basic fraction in the ash which could be very beneficial in raising the ash fusion temperature. 

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