Hydrogen Sulfide

Hydrogen sulfide is used commercially to purifY hydrochloric and sulfuric acid, to precipitate sulfides of metals, and to manufacture elemental sulfur and organosulfur compounds. Chemical production processes using hydrogen sulfide include the manufacture of mercaptans; pharmaceuticals; plastics; adhesives; television, cathode ray tubes (CRT), and fluorescent tube phosphors; dyes; pigments; biodegradable pesticides; ethylene; nylon; soda ash; sodium hydrosulfide; heavy water; and others. Hydrogen sulfide is used as a reducing agent in cresylic acid recovery. It is also used as a reagent in analytical chemistry. In waste water cleanup and groundwater restoration projects, hydrogen sulfide is used to immobilize heavy metals.
Hydrogen sulfide is generally found as a pungent colorless flammable gas, although it is commonly shipped as liquefied compressed gas (NIOSH, 2011). Its characteristic odor of “rotten eggs” cannot be considered indicative of its concentration, as olfactory fatigue occurs quite rapidly, even at relatively low concentration levels (100–150 ppm). It has a vapor density of 1.19, which makes it heavier than air and will cause it to accumulate in low lying areas rather than disperse easily in air and thus can present a hazard for workers in basements, subterranean locations, and confined spaces. It is soluble in water to a maximum of 0.4% by mass at room temperature. The auto ignition temperature is 260 °C and the flammable limits in air, % by volume are 4.5 (lower) and 45.5 (upper).