Iron bisulfide

Sulfides are usually present as a low-temperature forming, black iron sulfide (FeS) or a high-temperature forming, brown-black iron bisulfide (FeS2). Iron bisulfide can contain flecks of fool s gold, which has a metallic luster. Copper sulfide (CuS), which is a gray, dense, lustrous material, can also be present. Corrosion deposits containing sulfides are usually the result of process contamination. 

The deposits found here are primarily inorganic and usually are iron sulfide, iron bisulfide, or iron oxides. Quite often a combination of all three is found. This can be the most fouled part of a hydrofiner, as the metals are of lower alloys and there will be very little instrumentation on these systems. One refiner found his problem when he could not close his valves to bring down the unit. Considerable iron bisulfide also may be present. The compressors will have lube and seal oil systems that will also require cleaning. 

Reaction in the simulation begins slowly, but proceeds more rapidly as biomass accumulates, reflecting the reaction s autocatalytic nature. The reaction rate continues to increase until most of the acetate is consumed, at which point it slows abruptly to a near stop. In the simulation, dissolved ferrous iron is present in excess amount. The bisulfide produced as a result of bacterial sulfate reduction reacts with the iron,... 

This process is widespread in marine sediments but is most important at the continental margin sediments, where organic matter accumulation is fastest. Sulfate reduction can occur even meters below the sediment/water interface as long as seawater sulfate can diffuse, or be pumped by bioturbation induced through the actvities of sediment-dweUing organisms. The reaction yields the bisulfide anion (HS ), much of which diffuses upward and is reoxidized to SO in oxygenated seawater closer to the sediment surface. However, — 10% of the HS precipitates soluble Fe(II) to yield iron monosulfide ... 

This reaction leads to the production of sulfide species, such as H2S (hydrogen sulfide), I IS (bisulfide), and 82 (sulfide ion), which are the most reduced forms of sulfur. Sulfides are toxic most popularly known is H2S, which forms in rotten eggs and gives them their characteristic pungent odor. Sulfides are also important in causing the chemical precipitation of many metals, such as iron, copper, lead, and zinc, which form solids (such as FeS, CuS, PbS, ZnS) on reaction with S2. ... 

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