Hydrogen sulfide is present in very large amounts in raw natural gas and also occurs in large amounts during the refining of petroleum crude oil. In fact, the vast majority of the 66,000,000 metric tons of elemental sulfur produced worldwide in 2006 was by-product sulfur from petroleum refining and natural gas processing plants. It is also present in volcanic gases and some water well sources
Hydrogen sulfide is a highly toxic and flammable gas (flammability range: 4.0 to 46 volume % in air). It is heavier than air and tends to accumulate at the bottom of poorly ventilated, confined spaces.
At high temperature (about 1000 °C) and with the use of a catalyst, sulfur dioxide will react with hydrogen sulfide to form elemental sulfur and water (in the form of steam). This is commonly accomplished by the Claus process, the primary method of converting hydrogen sulfide into elemental sulfur.
Hydrogen sulfide is readily soluble in water, amounting to 4.1 grams per litre of water at 20 °C which is equivalent to 0.41 weight %. When it is in solution in water, the H2S forms a weak acid (sometimes referred to as hydrosulfuric acid) containing hydrosulfide and sulfide ions (HS− and S2−). The solubility is further enhanced in alkaline solutions due to increased ionization.
Hydrogen sulfide reacts with alcohols to form thiols.
- 0.00047 ppmv is the recognition threshold, the concentration at which 50% of humans can detect the characteristic foul odor of hydrogen sulfide.
- At 100 – 150 ppmv, the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger.
- At 200 ppmv, the central nervous system is depressed.
- At 500 ppmv, the cardiovascular system is depressed.
- At 1000 ppmv, the central nervous system is paralyzed and death occurs.
- Sulfur production report by the United States Geological Survey
- Carl L. Yaws (June 25, 2001). Matheson Gas Data Handbook, 7th Edition. McGraw-Hill. ISBN 0-07-135851-4.
- Air Liquide Gas Encyclopedia
- CCOHS Chemical Name: Hydrogen sulfide From the website of the Canadian Centre for Occupational Health and Safety (CCOHS)
- Toxicological Profile for Hydrogen Sulfide July 2006, U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry (ATSDR)
- Odor perception and physiological response
- Peter D. Bryson (September 1996). Comprehensive Review In Toxicology For Emergency Clinicians, Third Edition. Taylor and Francis, p. 368. ISBN 1-56032-612-3.