Hydrogen sulfide layer

For determing the concentration of hydrogen sulfide in the product gas, a Gow-Mac thermal conductivity cell (Model 10-952) was used. The cell was equipped with four matched pairs of AuW filaments, especially used because of their resistance to corrosion from the hydrogen sulfide. Layers of styrofoam were used to insulate the cell from changes in ambient temperature. This detector was found to be very sensitive to changes in the flow-rate. 

The horizontal extent of the H2S-containing zone is determined by the local bathymetry and the depth of the upper boundary of the hydrogen sulfide layer. The zone tends to be confined to the deepest portion of the western basin. We know that, at least sometimes, there exists also a separate pool of H2S in the relatively deep Chernyshev Bay [14], disconnected from the main western basin by a sUl, but this location is undersampled. 

Electrochemical treeing is appHed in those cases of water treeing in which the water contains solute ions which move under the action of an electric field and are detected within the insulation layer, or at an electrode surface after having passed through the insulation. They are not encountered as often as the first two classes, for example, trees formed in a cable exposed to a hydrogen sulfide environment called sulfide trees. 

Black Liquor Soap Acidulation. Only two-thirds of a typical black Hquor soap consists of the sodium salts of fatty acids and resin acids (rosin). These acids are layered in a Hquid crystal fashion. In between these layers is black Hquor at the concentration of the soap skimmer, with various impurities, such as sodium carbonate, sodium sulfide, sodium sulfate, sodium hydroxide, sodium Hgnate, and calcium salts. This makes up the remaining one-third of the soap. Cmde tall oil is generated by acidifying the black Hquor soap with 30% sulfuric acid to a pH of 3. This is usually done in a vessel at 95°C with 20—30 minutes of vigorous agitation. Caution should be taken to scmb the hydrogen sulfide from the exhaust gas. 

This 0 -benrylmercaptopropionylglycine (60 g) is dissolved in 400 ml of liquid ammonia, kept at about -50 C, and 12g of sodium metal is gradually added thereto. After the reaction, excess ammonia is removed therefrom, the residue is dissolved in water, washed with ether and the residual aqueous layer is adjusted to pH 1 with hydrochloric acid and concentrated in vacuo in a stream of hydrogen sulfide. The crystalline residue is dried and recrystallired from ethyl acetate to give 25 g of 0 -mercaptopropionylglycine of melting point 95°C to 97°C. 

For the corrosion process to proceed, the corrosion cell must contain an anode, a cathode, an electrolyte and an electronic conductor. When a properly prepared and conditioned mud is used, it causes preferential oil wetting on the metal. As the metal is completely enveloped and wet by an oil environment that is electrically nonconductive, corrosion does not occur. This is because the electric circuit of the corrosion cell is interrupted by the absence of an electrolyte. Excess calcium hydroxide [Ca(OH)j] is added as it reacts with hydrogen sulfide and carbon dioxide if they are present. The protective layer of oil film on the metal is not readily removed by the oil-wet solids as the fluid circulates through the hole. 

Copper and the Copper Alloys. Copper and its alloys are relatively resistant to corrosion dry, unpolluted air rarely affects them at normal temperatures surfaces of the metal or its alloys exposed to polluted air, even under ordinary atmospheric conditions, however, are tarnished by pollutants such as hydrogen sulfide and/or carbon dioxide. Given sufficient time, the activity of the pollutants result in the formation of a usually green layer, known as patina, which coats and surrounds the bulk of the metal or alloy (see Fig. 40). If the patina is chemically stable, that is, if it is hard, is non-porous, and covers the entire surface of an object, it protects the underlying metal core from further corrosion. Such a patina consists mostly of basic... 

Hydrogen Sulfide. Hydrogen sulfide is a foul-smelling gas that is released into the atmosphere from volcanoes as well as in the course of decay of animal tissues. As an air pollutant, it reacts with almost all metals, with the exception of gold, forming a dark-colored corrosive layer of metal sulfide, commonly known as tarnish, which discolors the exposed surface of most metals. 

The potential production of sulfide depends on the biofilm thickness. If the flow velocity in a pressure main is over 0.8-1 ms-1, the corresponding biofilm is rather thin, typically 100-300 pm. However, high velocities also reduce the thickness of the diffusional boundary layer and the resistance against transport of substrates and products across the biofilm/water interphase. Totally, a high flow velocity will normally reduce the potential for sulfide formation. Furthermore, the flow conditions affect the air-water exchange processes, e.g., the emission of hydrogen sulfide (cf. Chapter 4). 

The growth mechanism for the IF-MS2 (M = Mo,W) materials by the sulfidi-zation of the respective oxide nanoparticles has been studied in detail (12, 31). The growth mechanism is schematically illustrated in Fig. 4 (31a). Here oxide nanoparticles are sulfidized on the surface at temperatures between 800 and 950 °C in an almost instantaneous reaction. Once the first sulfide layer enfolds the oxide nanoparticle its surface is completely passivated, and hence sintering of the nanoparticles is avoided. In the next step, which may last a few minutes, reduction of the oxide nanoparticle core by hydrogen takes place. In the third step, which is rather slow and may take a few hours, depending on the size of the nanoparticles... 

Decomposition of hydrogen sulfide. M0S2 catalyst either in layer form (see inner layer in previous column) or in pellet form (see alternative systems 1 and 2, below)... 

The corrosion behavior and dissolution mechanism of nickel in acid solutions with hydrogen sulfide (H2S) was studied. It was found that the dissolution of nickel is influenced by both the nickel sulfide layer formed on the electrode surface and the acceleration effect of H2S [56]. 

Traces of sulfides were determined by CSV at pH 10 in the presence of cobalt(II) ions. Cobalt sulfide was accumulated at —0.5 V (versus SCE), probably in the form of colloidal particles occluded into the mercury sulfide layer [73]. In the cathodic scan, CoS catalyzed evolution of hydrogen, which was reflected in the current peak at about —1.6 V. 

Fig. 3.5.6 Absorbance spectra of 190-layer cadmium-10, 12-diynoatc LB films after exposure to (a) hydrogen sulfide, (b) hydrogen selenide, or (c) hydrogen telluride. The spectra have been corrected for background (quartz and film). (From Ref. 31.)...

Malo-lactic Bacteria. Promptly separating the new wine from the thick layer of yeast and pulp particles is most important. Many wines are spoiled by procrastination. The yeast cells, if left in a thick layer, will begin to digest themselves and produce bad-smelling materials. Some breakdown products from this action have odors reminiscent of rotten eggs—the odor of hydrogen sulfide. Once the wine has acquired a rotten egg odor it is very difficult to remove it. 

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