Editing Hydrogen sulfide (section)

==Uses==
===Production of sulfur===
Hydrogen sulfide is mainly consumed as a precursor to elemental sulfur. This conversion, called the [[Claus process]], involves partial oxidation to sulfur dioxide.  The latter reacts with hydrogen sulfide to give elemental sulfur. The conversion is catalyzed by alumina.<ref>{{Cite book |last=Lee |first=J. D. |title=Concise inorganic chemistry |date=1998 |publisher=Blackwell Science |isbn=978-0-632-05293-6 |edition=5. ed., reprinted |location=Oxford |page=538}}</ref>

:{{chem2|2H2S + SO2→ 3S + 2H2O}}

===Production of thioorganic compounds===
Many fundamental [[organosulfur compound]]s are produced using hydrogen sulfide. These include [[methanethiol]], [[ethanethiol]], and [[thioglycolic acid]].<ref name=ullmann/>  Hydrosulfides can be used in the production of [[thiophenol]].<ref>{{cite journal |last1=Khazaei |first1=Ardeshir |last2=Kazem-Rostami |first2=Masoud |last3=Moosavi-Zare |first3=Ahmad |last4=Bayat |first4=Mohammad |last5=Saednia |first5=Shahnaz |title=Novel One-Pot Synthesis of Thiophenols from Related Triazenes under Mild Conditions |journal=Synlett |date=August 2012 |volume=23 |issue=13 |pages=1893–1896 |doi=10.1055/s-0032-1316557 |s2cid=196805424 }}</ref>

===Production of metal sulfides===
Upon combining with [[alkali metal]] bases, hydrogen sulfide converts to alkali hydrosulfides such as [[sodium hydrosulfide]] and [[sodium sulfide]]:
:{{chem2|H2S + NaOH → NaSH + H2O}}
:{{chem2|NaSH + NaOH → Na2S + H2O}}
Sodium sulfides are used in the [[paper making]] industry. Specifically, salts of {{chem2|SH−}} break bonds between lignin and cellulose components of [[pulp (paper)|pulp]] in the [[Kraft process]].<ref name=ullmann/>

As indicated above, many metal ions react with hydrogen sulfide to give the corresponding metal sulfides.  Oxidic ores are sometimes treated with hydrogen sulfide to give the corresponding metal sulfides which are more readily purified by [[flotation process|flotation]].Metal parts are sometimes [[Passivation (chemistry)|passivated]] with hydrogen sulfide. Catalysts used in [[hydrodesulfurization]] are routinely activated with hydrogen sulfide.<ref name=ullmann/>

=== Occurrence ===
[[Image:Deposit from hydrogen sulphide.jpg|thumb|Deposit of [[sulfur]] on a rock, caused by [[volcanic gas]]]]

[[Volcano]]es and some [[hot spring]]s (as well as [[Mineral spring|cold springs]]) emit some {{chem2|H2S}}. Hydrogen sulfide can be present naturally in well water, often as a result of the action of [[sulfate-reducing bacteria]].<ref>{{cite web|title=Hydrogen Sulphide In Well Water|url=https://extension.psu.edu/hydrogen-sulfide-rotten-egg-odor-in-water-wells|access-date=4 September 2018}}</ref>{{better source needed|date = January 2020}} Hydrogen sulfide is produced by the human body in small quantities through bacterial breakdown of proteins containing sulfur in the intestinal tract; it therefore contributes to the characteristic odor of flatulence. It is also produced in the mouth ([[halitosis]]).<ref name="ATSDR">{{cite web|author=Agency for Toxic Substances and Disease Registry|date=July 2006|title=Toxicological Profile For Hydrogen Sulfide|url=http://www.atsdr.cdc.gov/toxprofiles/tp114.pdf|access-date=2012-06-20|page=154}}</ref>

A portion of global {{chem2|H2S}} emissions are due to human activity. By far the largest industrial source of {{chem2|H2S}} is [[oil refinery|petroleum refineries]]: The [[hydrodesulfurization]] process liberates sulfur from [[petroleum]] by the action of hydrogen. The resulting {{chem2|H2S}} is converted to elemental sulfur by partial combustion via the [[Claus process]], which is a major source of elemental sulfur. Other anthropogenic sources of hydrogen sulfide include [[coke (fuel)|coke]] ovens, [[paper mill]]s (using the Kraft process), tanneries and [[sewerage]]. {{chem2|H2S}} arises from virtually anywhere where elemental sulfur comes in contact with organic material, especially at high temperatures. Depending on environmental conditions, it is responsible for deterioration of material through the action of some sulfur oxidizing microorganisms. It is called [[biogenic sulfide corrosion]].{{cn|date=January 2025}}

In 2011 it was reported that increased concentrations of {{chem2|H2S}} were observed in the [[Bakken formation]] crude, possibly due to oil field practices, and presented challenges such as "health and environmental risks, corrosion of wellbore, added expense with regard to materials handling and pipeline equipment, and additional refinement requirements".<ref>{{cite web|url=http://www.onepetro.org/mslib/servlet/onepetropreview?id=SPE-141434-MS|title=Home - OnePetro|author=OnePetro|work=onepetro.org|access-date=2013-08-14|archive-date=2013-10-14|archive-url=https://web.archive.org/web/20131014053027/http://www.onepetro.org/mslib/servlet/onepetropreview?id=SPE-141434-MS|url-status=dead}}</ref>

Besides living near gas and oil drilling operations, ordinary citizens can be exposed to hydrogen sulfide by being near [[Sewage treatment|waste water treatment]] facilities, [[landfill]]s and farms with manure storage. Exposure occurs through breathing contaminated air or drinking contaminated water.<ref>{{cite web|title=Hydrogen Sulfide|url=https://www.atsdr.cdc.gov/toxfaqs/tfacts114.pdf|publisher=Agency for Toxic Substances and Disease Registry|date=December 2016}}</ref>

In [[Landfill|municipal waste landfill sites]], the burial of [[Organic matter|organic material]] rapidly leads to the production of [[anaerobic digestion]] within the waste mass and, with the humid atmosphere and relatively high temperature that accompanies [[biodegradation]], [[biogas]] is produced as soon as the air within the waste mass has been reduced. If there is a source of sulfate bearing material, such as plasterboard or natural [[gypsum]] (calcium sulfate dihydrate), under anaerobic conditions [[Sulfate-reducing microorganisms|sulfate reducing bacteria]] converts this to hydrogen sulfide. These bacteria cannot survive in air but the moist, warm, anaerobic conditions of buried waste that contains a high source of carbon – in inert landfills, paper and glue used in the fabrication of products such as [[Drywall|plasterboard]] can provide a rich source of carbon<ref>{{Cite journal |doi = 10.1016/S1093-0191(00)00056-3|title = Sulfate leaching from recovered construction and demolition debris fines|journal = Advances in Environmental Research|volume = 5|issue = 3|pages = 203–217|year = 2001|last1 = Jang|first1 = Yong-Chul|last2 = Townsend|first2 = Timothy| bibcode=2001AdvER...5..203J }}</ref> – is an excellent environment for the formation of hydrogen sulfide.

In industrial anaerobic digestion processes, such as [[Wastewater treatment|waste water treatment]] or the [[Anaerobic digestion|digestion of organic waste from agriculture]], hydrogen sulfide can be formed from the reduction of sulfate and the degradation of amino acids and proteins within organic compounds.<ref>{{Cite web|url=http://www.valorgas.soton.ac.uk/Pub_docs/JyU%20SS%202011/CC%201.pdf|title=Anaerobic digestion fundamentals|last=Cavinato|first=C. |date=2013|orig-year=2013}}</ref> Sulfates are relatively non-inhibitory to [[Methanobacteria|methane forming bacteria]] but can be reduced to {{chem2|H2S}} by [[Sulfate-reducing microorganisms|sulfate reducing bacteria]], of which there are several genera.<ref>{{cite journal |last1=Pokorna |first1=Dana |last2=Zabranska |first2=Jana |title=Sulfur-oxidizing bacteria in environmental technology |journal=Biotechnology Advances |date=November 2015 |volume=33 |issue=6 |pages=1246–1259 |doi=10.1016/j.biotechadv.2015.02.007 |pmid=25701621 }}</ref>

===Removal from water===
A number of processes have been designed to remove hydrogen sulfide from [[drinking water]].<ref>{{cite web |last1=Lemley |first1=Ann T. |last2=Schwartz |first2=John J. |last3=Wagenet |first3=Linda P. |title=Hydrogen Sulfide in Household Drinking Water |url=http://waterquality.cce.cornell.edu/publications/CCEWQ-07-HydrogenSulfide.pdf |publisher=Cornell University |archive-url=https://web.archive.org/web/20190819132148/http://waterquality.cce.cornell.edu/publications/CCEWQ-07-HydrogenSulfide.pdf |archive-date=19 August 2019 |url-status=dead}}</ref>

; Continuous chlorination: For levels up to 75&nbsp;mg/L [[chlorine]] is used in the purification process as an oxidizing chemical to react with hydrogen sulfide. This reaction yields insoluble solid sulfur. Usually the chlorine used is in the form of [[sodium hypochlorite]].<ref>{{cite web|title=Hydrogen Sulfide (Rotten Egg Odor) in Pennsylvania Groundwater Wells|url=http://extension.psu.edu/natural-resources/water/drinking-water/water-testing/pollutants/hydrogen-sulfide-rotten-egg-odor-in-pennsylvania-groundwater-wells|website=Penn State|publisher=Penn State College of Agricultural Sciences|access-date=1 December 2014|archive-date=4 January 2015|archive-url=https://web.archive.org/web/20150104222350/http://extension.psu.edu/natural-resources/water/drinking-water/water-testing/pollutants/hydrogen-sulfide-rotten-egg-odor-in-pennsylvania-groundwater-wells|url-status=dead}}</ref>

; Aeration: For concentrations of hydrogen sulfide less than 2&nbsp;mg/L [[aeration]] is an ideal treatment process. Oxygen is added to water and a reaction between oxygen and hydrogen sulfide react to produce odorless sulfate.<ref>{{cite web|last1=McFarland|first1=Mark L.|last2=Provin|first2=T. L.|title=Hydrogen Sulfide in Drinking Water Treatment Causes and Alternatives|url=http://soiltesting.tamu.edu/publications/L-5312.pdf|publisher=Texas A&M University|access-date=1 December 2014|archive-date=30 July 2020|archive-url=https://web.archive.org/web/20200730113102/http://soiltesting.tamu.edu/publications/L-5312.pdf|url-status=dead}}</ref>

===Removal from fuel gases===
Hydrogen sulfide is commonly found in raw natural gas and biogas. It is typically removed by [[amine gas treating]] technologies. In such processes, the hydrogen sulfide is first converted to an ammonium salt, whereas the natural gas is unaffected.<ref name=Kohl>{{cite book|author1=Arthur Kohl |author2=Richard Nielson |title=Gas Purification|edition=5th|publisher=Gulf Publishing|year=1997|isbn=0-88415-220-0}}</ref><ref name=Gary>{{cite book|author1=Gary, J.H.  |author2=Handwerk, G.E.|title=Petroleum Refining Technology and Economics|edition=2nd|publisher=Marcel Dekker, Inc|year=1984|isbn=0-8247-7150-8}}</ref>
: {{chem2|RNH2 + H2S ⇌ [RNH3]+ + SH−}}
The bisulfide anion is subsequently regenerated by heating of the amine sulfide solution. Hydrogen sulfide generated in this process is typically converted to elemental sulfur using the [[Claus Process]].

[[Image:AmineTreating.png|frame|center|[[Process flow diagram]] of a typical amine treating process used in petroleum refineries, natural gas processing plants and other industrial facilities]]