Sulfides Sulfite addition

Others recommend treatment to remove the compound. Hydrogen sulfide can be removed or reduced from RO feed water using some iron filters (such as manganese greensand and Filox, see Chapter 8.1.5) or a complicated combination of oxidation, coagulation and filtration, sulfite addition, and rechlorination.9... 

Visible Light-Induced Formation of Addition of sulfite shown to enhance the clea-Hydrogen and Thiosulfate from vage of H2S into H2 and S. See also Refs. 495-Aqueous Sulfide/Sulfite Solutions 497 and Ref. 500 for follow-up work, in CdS Suspensions. 499... 

Fdred as electron donor. Some S, exchangeable with H S, was also associated with a protein fraction. Chlorella extracts also catalyzed the reduction of [ S]APS to [ S]sulfide. In addition S, exchangeable with HjS, was incorporated into protein at rates similar to those using GS- SOj. When either GS- S03 or ([ S]APS plus GSH) was supplied in the absence of Fd, was incorporated into the protein in a form which exchanged with sulfite. After incubation with Fd d the S exchanged with sulfide. These results suggest that GS-SOj, which can be formed from GSH and APS, is protein bound and is reduced to protein-bound-GS-S by Fdred ... 

Sulfides, sulfites and thiosulfates can be quantitatively oxidized to sulfates by addition of a few drops of 10 % hydrogen peroxide. 

Mapson (14) found that in solutions of pH 0.6 there is no significant condensation of formaldehyde with ascorbic acid. However, at this pH sulfides, sulfites, and thiol compounds combine readily with formaldehyde. He, therefore, proposed that the indophenol titration be carried out at pH 0.6 after the addition of formaldehyde to estimate ascorbic acid in the presence of the interfering sulfur compounds. 

These three methods are employed commercially. In addition, decomposition of polythionates in alkaline solution or their reaction with sulfide or sulfite gives thiosulfates ... 

Sodium thiosulfate is determined by titration with standard iodine solution (37). Sulfate and sulfite are determined together by comparison of the turbidity produced when barium chloride is added after the iodine oxidation with the turbidity produced by a known quantity of sulfate iu the same volume of solution. The absence of sulfide is iadicated when the addition of alkaline lead acetate produces no color within one minute. 

Many carbonate, sulfite, and sulfide precipitates can be dissolved by the addition of acid, because the anions react with the acid to form a gas that bubbles out of solution. For example, in a saturated solution of zinc carbonate, solid ZnCO, is in equilibrium with its ions ... 

Sulfite reductase catalyzes the six-electron reduction of sulfite to sulfide, m essential enzymatic reaction in the dissimilatory sulfate reduction process. Several different types of dissimilatory sulfite reductases were already isolated from sulfate reducers, namely desul-foviridin (148-150), desulforubidin (151, 152), P-582 (153, 154), and desulfofuscidin (155). In addition to these four enzymes, an assimila-tory-type sulfite reductase was also isolated from D. vulgaris. Although all these enzymes have significantly different subunit composition and amino acid sequences, it is interesting to note that, as will be discussed later, all of them share a unique type of cofactor. 

Reducing smelting furnaces that produce a high-sulfidity, kraft-like green liquor are now employed at sodium-based sulfite mills. U.S. EPA anticipates that it would be necessary to replace the existing recovery boilers at ammonia-based mills if chemical substitution to a sodium base were employed. Additionally, it is likely that, because the heat value of sodium spent liquor is lower than ammonia spent liquor, evaporator modification may he required if excess capacity does not already exist. 

The synthesis of polysulfide elastomers involves the use of a small amount of trichloroalkane in addition to dichloroalkane and sodium sulfide in order to form a branched polymer. The prepolymer is treated with a mixture of sodium hydrosulfide and sodium sulfite followed by acidification to convert all end-groups to thiol groups. Further polymerization and crosslinking is achieved by oxidative coupling of the thiol end-groups by treatment with lead dioxide, p-quinone dioxime, or other oxidizing agent... 

ATS [Ammonium thiosulfate] A process for removing residual sulfur dioxide from Claus tail gas by absorption in aqueous ammonia to produce ammonium sulfite and bisulfite. Addition of hydrogen sulfide from the Claus unit produces saleable ammonium thiosulfate. Developed by the Pritchard Corporation and first operated by the Colorado Interstate Gas Company at Table Rock, WY. 

Addition of certain sulfur-containing nucleophiles constitutes the basis of several analytical procedures. Among these nucleophiles arc Rodium sulfite,1 75 sodium thiosulfate,1491 and hydrogen sulfide.635 In each case, OH ions released after attack of the nucleophile on the epoxide can be titrated continuously with standard acid to maintain a constant pH.1491... 

Figure 2. Radioactivity chromatogram of sulfur compounds derivatized with monobromobimane. The reversed-phase HPLC separation is based on the hydrophobic properties of the bimane-sulfur adducts but peak area is based on "S-radioactivity of the compounds. At time 0 sulfite and thiosulfate impurities are present before addition of the hepatopancrease tissue homogenate. This was a 60 min experiment to determine the sulfide detoxifying functions of the hepatopancrease of the hydrothermal vent crab Bythograea thermydron. During this time the proportion of radioactivity in sulfide rapidly decreases and thiosulfate and sulfate accumulate as end products. Two intermediates, pi and p2 accumulate then decrease during the experiment. The two intermediates are believed to be polysulfides based on similar elution times of polysulfide standards. (Figure is the unpublished chromatograms from the data in Vetter et al. (24)-) continued on next page.

Figure 5. The metabolism of 3S-S radiolabeled sulfide by boiled and intact isolated Solemya reidi mitochondria. Time zero is prior to addition of mitochondria. When mitochondria are added there is a rapid decrease in sulfide concentration caused partially by dilution of the total volume and partially by binding of sulfide to protein. In the boiled preparation there is very little oxidation of sulfide and no appearance of oxidized products. In the healthy mitochondria the sulfide is rapidly oxidized to thiosulfate. Sulfite and sulfate did not appear as oxidation products. The health of the isolated mitochondria was monitored by oxygen consumption rate in the chamber with succinate as substrate and by the ability to inhibit succinate stimulated respiration with respiratory inhibitors such as cyanide. Error bars represent plus and minus one standard deviation of the mean of three runs.

A major contribution of this paper was pointing out the importance of bioturbation and bioirrigation on chemical processes associated with carbonate dissolution. In the movement of sulfidic sediment from depth to near the interface by biological processes, oxidation of the sediment produces sulfuric acid which ends up titrating alkalinity, lowering pH, and thus lowers saturation state (e.g., Berner and Westrich, 1985). Actually this process is very complex, involving many reactive intermediate compounds such as sulfite, thiosulfate, polythionates, etc. Aller and Rude (1988) demonstrated an additional complication to this process. Mn oxides may oxidize iron sulfides by a bacterial pathway that causes the saturation state of the solution to rise with respect to carbonate minerals, rather than decrease as is the case when oxidation takes place with oxygen. 

Addition Reaction. The double bond of dehydroalanine and e-methyl dehydroalanine formed by the e-elimination reaction (Equation 6) is very reactive with nucleophiles in the solution. These may be added nucleophiles such as sulfite (44). sulfide (42), cysteine and other sulfhydryl compounds (20,47), amines such as a-N-acetyl lysine (47 ) or ammonia (48). Or the nucleophiles may be contributed by the side chains of amino acid residues, such as lysine, cysteine, histidine or tryptophan, in the protein undergoing reaction in alkaline solution. Some of these reactions are shown in Figure 1. Friedman (38) has postulated a number of additional compounds, including stereo-isomers for those shown in Figure 1, as well as those compounds formed from the reaction of B-methyldehydroalanine (from 6 elimination of threonine). He has also suggested a systematic nomenclature for these new amino acid derivatives (38). As pointed out by Friedman the stereochemistry can be complicated because of the number of asymmetric carbon atoms (two to three depending on derivative) possible. 

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