Sulfur or
sulphur ( ,
see spelling below) is the
chemical elementA chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons.Common examples of elements...
that has the
atomic numberIn chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
16. It is denoted with the symbol
S. It is an abundant,
multivalentIn chemistry, valence, also known as valency or valency number, is a measure of the number of chemical bonds formed by the atoms of a given element...
non-metal. Sulfur, in its native form, is a yellow
crystalA crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is crystallography...
line solid. In
natureNature, in the broadest sense, is equivalent to the natural world, physical world, or material world. "Nature" refers to the phenomena of the physical world, and also to life in general...
, it can be found as the pure element and as
sulfideA sulfide is a chemical compound containing sulfur in its lowest oxidation number of −2.- Properties :...
and
sulfateIn inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
minerals. It is an essential element for life and is found in two
amino acidAmino acids are molecules containing an amine group, a carboxylic acid group and one of the twenty R-groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H
2NCHRCOOH, where R is an organic substituent...
s,
cysteineCysteine is an α-amino acid with the chemical formula HO
2CCHCH
2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is nonpolar and thus cysteine is usually classified as...
and
methionineMethionine is an α-amino acid with the chemical formula HO
2CCHCH
2CH
2SCH
3. This essential amino acid is classified as nonpolar.-Function:...
. Its commercial uses are primarily in
fertilizerFertilizers are chemical compounds applied to promote plant and fruit growth. Fertilizers are usually applied either through the soil or by foliar feeding...
s, but it is also widely used in black
gunpowderGunpowder, also called black powder, is a mixture of sulfur, charcoal, and potassium nitrate. It burns rapidly, producing volumes of hot solids and gases which can be used as a propellant in firearms and as a pyrotechnic composition in fireworks. The term gunpowder also refers broadly to any...
,
matchA match is a consumable tool for lighting a fire in controlled circumstances on demand. Matches are readily available, being sold by tobacconists and many other kinds of shops. Matches are rarely sold singly; they are sold in multiples, packaged in match boxes or matchbooks...
es,
insecticideAn insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
s and
fungicideFungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
s. Elemental sulfur crystals are commonly sought after by mineral collectors for their brightly colored
polyhedronA polyhedron is often defined as a geometric solid with flat faces and straight edges .This definition of a polyhedron is not very precise, and to a modern mathematician is...
shapes. In nonscientific contexts, it can also be referred to as
brimstone.
History
Sulfur (
SanskritSanskrit is a historical Indo-Aryan language, one of the liturgical languages of Hinduism and Buddhism, and one of the 22 official languages of India. It is also declared as a classical language by the government of India....
,
sulvari;
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. Through the Roman conquest, Latin spread throughout the Mediterranean and a large part of Europe...
Sulphurium) was known in ancient times and is referred to in the
TorahThe term "Torah" , refers either to the Five Books of Moses or to the entirety of Judaism's founding legal and ethical religious texts...
(Genesis).
English translations of the BibleThe efforts of translating the Bible from its original languages into over 2,000 others have spanned more than two millennia. Partial translations of the Bible into languages of the English people can be traced back to the end of the 7th century, including translations into Old English and Middle...
commonly referred to burning sulfur as "brimstone", giving rise to the name of '
fire-and-brimstoneFire and brimstone are signs of God's wrath in the Hebrew Bible , the New Testament, and the Qur'an. In the Bible, they often appear in reference to the fate of the unfaithful. "Brimstone," possibly the ancient name for sulfur, evokes the acrid odor of volcanic activity...
'
sermonA sermon is an oration by a prophet or member of the clergy. Sermons address a Biblical, theological, religious, or moral topic, usually expounding on a type of belief, law or behavior within both past and present contexts...
s, in which listeners are reminded of the fate of
eternal damnation"Damnation" is the concept of condemnation by God such that results in a being's punishment. The word "damn" or "GodDamn" is widely used as a moderate profanity.-Religious:...
that await the unbelieving and unrepentant. It is from this part of the Bible that
HellIn many religious traditions, Hell is a place of suffering and punishment in the afterlife, often in the underworld. Religions with a linear divine history often depict Hell as endless...
is implied to "smell of sulfur" (likely due to its association with volcanic activity), although sulfur, in itself, is in fact odorless. The "smell of sulfur" usually refers to either the odor of
hydrogen sulfideHydrogen sulfide is the chemical compound with the formula H
2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence....
, e.g. from rotten egg, or of burning sulfur, which produces
sulfur dioxideSulfur dioxide is the chemical compound with the formula SO
2. It is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide...
, the smell associated with burnt matches. The smell emanating from raw sulfur originates from a slow oxidation in the presence of air. Hydrogen sulfide is the principal odor of untreated
sewageSewage is water-carried wastes, in either solution or suspension, that flow away from a community. Also known as wastewater flows, sewage is the used water supply of the community. It is more than 99.9% pure water and is characterized by its volume or rate of flow, its physical condition, its...
and is one of several unpleasant smelling sulfur-containing components of
flatulenceFlatulence is the expulsion through the rectum of a mixture of gases that are byproducts of the digestion process of mammals and other animals. The mixture of gases is known as flatus, fart, or simply gas, and is expelled from the rectum in a process colloquially referred to as "passing gas" or...
(along with sulfur-containing
mercaptansIn organic chemistry, a thiol is a compound that contains the functional group composed of a sulfur-hydrogen bond . Being the sulfur analogue of an alcohol group , this functional group is referred to either as a thiol group or a sulfhydryl group...
).
A natural form of sulfur known as
shiliuhuang was known in China since the 6th century BC and found in
HanzhongHanzhong is a municipality in the southwest corner of Shaanxi province, in central China. The population in 2006 was approximately 3.74 million, in a municipal territory of 27 246 square kilometres. -History:...
. By the 3rd century, the Chinese discovered that sulfur could be extracted from
pyriteThe mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS
2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold due to its resemblance to gold...
. Chinese Daoists were interested in sulfur's flammability and its reactivity with certain metals, yet its earliest practical uses were found in
traditional Chinese medicineTraditional Chinese Medicine, also known as TCM , includes a range of traditional medical practices originating in China. Although well accepted in the mainstream of medical care throughout East Asia, it is considered an alternative medical system in much of the western world.TCM practices include...
. A
Song DynastyThe Song Dynasty was a ruling dynasty in China between 960 and 1279; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty. It was the first government in world history to issue banknotes or paper money, and the first Chinese government to establish a...
military treatise of 1044 AD described different formulas for Chinese black powder, which is a mixture of
potassium nitratePotassium nitrate is a chemical compound with the chemical formula KNO3. A naturally occurring mineral source of nitrogen, KNO3 constitutes a critical oxidizing component of black powder/gunpowder. In the past it was also used for several kinds of burning fuses, including slow...
,
charcoalCharcoal is the blackish residue consisting of impure carbon obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood, sugar, bone char, or other substances in the absence of oxygen...
, and sulfur. Early
alchemistsAlchemy is both a philosophy and a practice with an aim of achieving ultimate wisdom as well as immortality, involving the improvement of the alchemist as well as the making of several substances described as possessing unusual properties...
gave sulfur its own
alchemical symbolAlchemic symbols, originally devised as part of the protoscience of alchemy, were used to denote some elements and some compounds until the 18th century...
which was a triangle at the top of a cross.
In 1777,
Antoine LavoisierAntoine-Laurent de Lavoisier ; ), the father of modern chemistry, was a French noble prominent in the histories of chemistry and biology...
helped convince the scientific community that sulfur was an element and not a compound. In 1867, sulfur was discovered in underground deposits in
LouisianaThe State of Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state divided into parishes, which are local governments equivalent to counties...
and
TexasTexas is the second-largest U.S. state in both area and population, and the largest state in the contiguous United States.The name had wide usage among native Americans, meaning "friends" or "allies"...
. The overlying layer of earth was
quicksandQuicksand is a colloid hydrogel consisting of fine granular matter , clay, and salt water. In the name, as in that of quicksilver , "quick" does not mean "fast," but "living" ....
, prohibiting ordinary mining operations; therefore, the
Frasch processThe Frasch process is a method to extract sulfur from underground deposits. Most of the world's sulfur was obtained this way until the late 20th century, when sulfur recovered from petroleum sources became more commonplace...
was developed.
Spelling and etymology
The element has traditionally been spelled
sulphur in the United Kingdom (since the 14th century), most of the Commonwealth including India,
MalaysiaMalaysia is a country in Southeast Asia that consists of thirteen states and three Federal Territories, with a total landmass of . The capital city is Kuala Lumpur, while Putrajaya is the seat of the federal government. The population stands at over 28 million inhabitants...
, South Africa, and Hong Kong, along with the rest of the
CaribbeanThe Caribbean is a region consisting of the Caribbean Sea, its islands , and the surrounding coasts...
and
IrelandIreland is a country in north-western Europe. The modern sovereign state occupies about five-sixths of the island of Ireland, which was partitioned on 3 May 1921. It is a parliamentary democracy and a republic...
, but
sulfur in the United States, while both spellings are used in Australia, New Zealand, Canada, and the
PhilippinesThe Philippines officially known as the Republic of the Philippines, is a country in Southeast Asia with Manila as its capital city. It comprises 7,107 islands in the western Pacific Ocean....
. IUPAC adopted the spelling “sulfur” in 1990, as did the
Royal Society of ChemistryThe Royal Society of Chemistry is a learned society in the United Kingdom with the goal of "advancing the chemical sciences." The organisation carries out research, publishes journals, books and databases, as well as hosting conferences, seminars and workshops...
Nomenclature Committee in 1992. The
Qualifications and Curriculum AuthorityThe Qualifications and Curriculum Authority is an executive non-departmental public body of the Department for Children, Schools and Families in the United Kingdom...
for England and Wales recommended its use in 2000.
In Latin, the word is variously written
sulpur,
sulphur, and
sulfur (the Oxford Latin Dictionary lists the spellings in this order). It is an original Latin name and not a Classical Greek loan, so the
ph variant does not denote the Greek letter φ. Sulfur in Greek is
thion (θείον), whence comes the prefix thio-. The simplification of the Latin words p or ph to an f appears to have taken place towards the end of the classical period, with the f spelling becoming dominant in the medieval period.
Characteristics
At room temperature, sulfur is a soft, bright-yellow solid. Elemental sulfur has only a faint odor, similar to that of matches.
The odor associated with rotten eggs is due to
hydrogen sulfideHydrogen sulfide is the chemical compound with the formula H
2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence....
and organic sulfur compounds rather than elemental sulfur.
Sulfur burns with a blue flame that emits
sulfur dioxideSulfur dioxide is the chemical compound with the formula SO
2. It is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide...
, notable for its peculiar suffocating odor due to dissolving in the mucosa to form dilute
sulfurous acidSulfurous acid is the chemical compound with the formula H2SO3. There is no evidence that sulfurous acid exists in solution, but the molecule has been detected in the gas phase...
. Sulfur itself is insoluble in water, but
solubleSolubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a liquid solvent to form a homogeneous solution. The solubility of a substance strongly depends on the used solvent as well as on temperature and pressure...
in
carbon disulfideCarbon disulfide is a colorless, volatile liquid with the formula CS2. The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non-polar solvent...
— and to a lesser extent in other non-polar organic solvents such as
benzeneBenzene, or benzol, is an organic chemical compound with the molecular formula C6H6. It is sometimes abbreviated Ph–H. Benzene is a colorless and highly flammable liquid with a sweet smell and a relatively high melting point...
and
tolueneToluene, also known as methylbenzene, or Toluol, is a clear water-insoluble liquid with the typical smell of paint thinners, reminiscent of the related compound benzene. It is an aromatic hydrocarbon that is widely used as an industrial feedstock and as a solvent...
. Common
oxidation stateIn chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...
s of sulfur include −2, +2, +4 and +6. Sulfur forms stable compounds with all elements except the
noble gasThe noble gases are a group of chemical elements with very similar properties: under standard conditions, they are all odorless, colorless, monatomic gases, with a very low chemical reactivity...
es.
Sulfur in the solid state ordinarily exists as cyclic crown-shaped S
8 molecules.
The
crystallographyCrystallography is the experimental science of determining the arrangement of atoms in solids. In older usage, it is the scientific study of crystals...
of sulfur is complex. Depending on the specific conditions, the sulfur allotropes form several distinct
crystal structureIn mineralogy and crystallography, a crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a motif, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...
s, with rhombic and monoclinic S
8 best known.
A noteworthy property of sulfur is that the
viscosityViscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness." Thus, water is "thin," having a lower viscosity, while honey is "thick," having a higher viscosity...
in its molten state, unlike most other liquids, increases above temperatures of 200 °C due to the formation of
polymerA polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties.Due to the extraordinary...
s. The molten sulfur assumes a dark red color above this temperature. At higher temperatures, however, the viscosity is decreased as depolymerization occurs.
Amorphous or "plastic" sulfur can be produced through the rapid cooling of molten sulfur.
X-ray crystallographyX-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and diffracts into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture...
studies show that the amorphous form may have a
helicalA helix is a special kind of space curve, i.e. a smooth curve in three-space. As a mental image of a helix one may take the spring...
structure with eight atoms per turn. This form is metastable at room temperature and gradually reverts back to crystalline form. This process happens within a matter of hours to days but can be rapidly catalyzed.
Allotropes
Sulfur forms more than 30 solid
allotropeAllotropy or allotropism is a behavior exhibited by certain chemical elements: these elements can exist in two or more different forms, known as allotropes of that element. In each allotrope, the element's atoms are bonded together in a different manner...
s, more than any other element. Besides S
8, several other rings are known. Removing one atom from the crown gives S
7, which is more deeply yellow than S
8. HPLC analysis of "elemental sulfur" reveals an equilibrium mixture of mainly S
8, but also S
7 and small amounts of S
6. Larger rings have been prepared, including S
12 and S
18. By contrast, sulfur's lighter neighbor
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
only exists in two states of allotropic significance: O
2 and O
3.
SeleniumSelenium is a chemical element with the atomic number 34, represented by the chemical symbol Se, an atomic mass of 78.96. It is a nonmetal, chemically related to sulfur and tellurium, and rarely occurs in its elemental state in nature....
, the heavier analogue of sulfur, can form rings but is more often found as a polymer chain.
Isotopes
Sulfur has 25 known
isotopeIsotopes are different types of atoms of the same chemical element, each having a different number of neutrons. Correspondingly, isotopes differ in mass number but not in atomic number. The difference in the number of nucleons comes from a difference how many neutrons are in the atomic nucleus...
s, four of which are stable:
32S (95.02%),
33S (0.75%),
34S (4.21%), and
36S (0.02%). Other than
35S, the radioactive isotopes of sulfur are all short lived.
35S is formed from
cosmic rayCosmic rays are energetic particles originating from outer space that impinge on Earth's atmosphere. Almost 90% of all the incoming cosmic ray particles are protons, almost 10% are helium nuclei , and slightly under 1% are heavier elements and electrons...
spallationIn general, spallation is a process in which fragments of material are ejected from a body due to impact or stress. In nuclear physics, it is the process in which a heavy nucleus emits a large number of nucleons as a result of being hit by a high-energy particle, thus greatly reducing its atomic...
of
40argonArgon is a chemical element designated by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is present in the Earth's atmosphere at 0.94%. Terrestrially, it is the most abundant and most frequently used of the noble gases...
in the
atmosphereThe Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
. It has a
half-lifeHalf-life is the period of time, for a substance undergoing decay, to decrease by half. The name originally was used to describe a characteristic of unstable atoms , but may apply to any quantity which follows a set-rate decay....
of 87 days.
When sulfide
mineralA mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. A rock, by comparison, is an aggregate of minerals and/or mineraloids, and need not have a specific...
s are precipitated, isotopic equilibration among solids and liquid may cause small differences in the δS-34 values of co-genetic minerals. The differences between minerals can be used to estimate the temperature of equilibration. The δ
CCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
-13 and δS-34 of coexisting
carbonateIn chemistry, a carbonate is a salt or ester of carbonic acid, characterized by the presence of the carbonate ion, or a carbonate functional group O=C2....
s and sulfides can be used to determine the
pHpH is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations...
and
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
fugacityFugacity is a measure of a chemical potential in the form of 'adjusted pressure'. It reflects the tendency of a substance to prefer one phase over another, and can be literally defined as “the tendency to flee or escape”. At a fixed temperature and pressure, a homogeneous substance will have a...
of the ore-bearing fluid during ore formation.
In most
forestA forest is an area with a high density of trees. There are many definitions of a forest, based on the various criteria. These plant communities presently cover approximately 9.4% of the Earth's surface in many different regions and function as habitats for organisms, hydrologic flow modulators,...
ecosystems, sulfate is derived mostly from the atmosphere; weathering of ore minerals and evaporites also contribute some sulfur. Sulfur with a distinctive isotopic composition has been used to identify pollution sources, and enriched sulfur has been added as a tracer in
hydrologicHydrology is the study of the movement, distribution, and quality of water throughout Earth, and thus addresses both the hydrologic cycle and water resources...
studies. Differences in the
natural abundanceIn chemistry, natural abundance refers to the abundance isotopes of a chemical element as naturally found on a planet. The relative atomic mass of these isotopes is the atomic weight listed for the element in the periodic table...
s can also be used in systems where there is sufficient variation in the
34S of ecosystem components. Rocky Mountain lakes thought to be dominated by atmospheric sources of sulfate have been found to have different δS-34 values from lakes believed to be dominated by watershed sources of sulfate.
Occurrence
Elemental sulfur can be found near
hot springA hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are hot springs all over the earth, on every continent and even under the oceans and seas.-Definitions:...
s and volcanic regions in many parts of the world, especially along the
Pacific Ring of FireThe Pacific Ring of Fire is an area where large numbers of earthquakes and volcanic eruptions occur in the basin of the Pacific Ocean. In a 40,000 km horseshoe shape, it is associated with a nearly continuous series of oceanic trenches, volcanic arcs, and volcanic belts and/or plate movements...
. Such volcanic deposits are currently mined in
IndonesiaThe Republic of Indonesia is a country in Southeast Asia and Oceania. Indonesia comprises 17,508 islands. With an estimated population of around 237 million people, it is the world's fourth most populous country, with the world's largest population of Muslims.Indonesia is a republic, with an...
,
ChileChile, officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, and Japan.
SicilySicily is the largest island in the Mediterranean Sea. It is an autonomous region of Italy. Several much smaller islands surrounding it are considered to be part of Sicily....
is also famous for its sulfur mines. Sulfur deposits are polycrystalline, and the largest documented single crystal measured 22x16x11 cm
3.
Significant deposits of elemental sulfur also exist in salt domes along the coast of the
Gulf of MexicoThe Gulf of Mexico is the ninth largest body of water in the world. Considered a smaller part of the Atlantic Ocean, it is an ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United...
, and in
evaporiteEvaporites are water-soluble mineral sediments that result from the evaporation of bodies of surficial water. Evaporites are considered sedimentary rocks.- Formation of evaporite rocks :...
s in eastern Europe and western Asia. The sulfur in these deposits is believed to come from the action of anaerobic bacteria on sulfate minerals, especially
gypsumGypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO
4·2H
2O.-Crystal varieties:...
, although apparently native sulfur may be produced by geological processes alone, without the aid of living organisms (see below). However, fossil-based sulfur deposits from salt domes are the basis for commercial production in the United States, Poland, Russia,
TurkmenistanRepublic of Turkmenistan is a country in Central Asia. Until 1991, it was a constituent republic of the Soviet Union, the Turkmen Soviet Socialist Republic...
, and
UkraineUkraine is a country in Eastern Europe. It is bordered by Russia to the east; Belarus to the north; Poland, Slovakia, and Hungary to the west; Romania and Moldova to the southwest; and the Black Sea and Sea of Azov to the south. The city of Kiev is both the capital and the largest city of...
.
Sulfur production through
hydrodesulfurizationHydrodesulfurization is a catalytic chemical process widely used to remove sulfur from natural gas and from refined petroleum products such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils...
of oil, gas, and the
Athabasca Oil SandsThe Athabasca Oil Sands are large deposits of bitumen, or extremely heavy crude oil, located in northeastern Alberta, Canada - roughly centered around the boomtown of Fort McMurray...
has produced a surplus — huge stockpiles of sulfur now exist throughout Alberta, Canada.
Common naturally occurring sulfur compounds include the sulfide minerals, such as
pyriteThe mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS
2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold due to its resemblance to gold...
(iron sulfide),
cinnabarCinnabar, sometimes written cinnabarite, is a name applied to red mercury sulfide , or native vermillion, the common ore of mercury. The name comes from the Greek - "kinnabari" - used by Theophrastus, and was probably applied to several distinct substances. Other sources say the word comes from the...
(mercury sulfide),
galenaGalena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...
(lead sulfide),
sphaleriteSphalerite is a mineral that is the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron. When iron content is high it is an opaque black variety, marmatite. It is usually found in association with galena, pyrite, and other sulfides...
(zinc sulfide) and
stibniteStibnite, sometimes called antimonite, is a sulfide mineral with the formula Sb
2S
3. This soft grey material crystallizes in an orthorhombic space group. It is the most important source for the metalloid antimony...
(antimony sulfide); and the sulfates, such as gypsum (calcium sulfate),
aluniteAlunite, or alumstone, is a sulfate mineral that was first observed in the 15th century in Monti della Tolfa, north of Rome, where it was mined for the manufacture of alum. First called aluminilite by J.C. Delametherie in 1707, this name was contracted by François Beudant in 1824 to...
(potassium aluminium sulfate), and
bariteBaryte, or barite, is a mineral consisting of barium sulfate. The baryte group consists of baryte, celestine, anglesite and anhydrite. Baryte itself is generally white or colorless, and is the main source of barium...
(barium sulfate). It occurs naturally in volcanic emissions, such as from
hydrothermal ventA hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots....
s, and from bacterial action on decaying sulfur-containing organic matter.
The distinctive colors of
JupiterJupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with a mass slightly less than one-thousandth that of the Sun but is two and a half times the mass of all of the other planets in our Solar System combined. Jupiter is classified as a gas...
's
volcanic3. Conduit
4. Base
5. Sill
6. Dike
7. Layers of ash emitted by the volcano
8. Flank| 9. Layers of lava emitted by the volcano
10. Throat
11. Parasitic cone
12. Lava flow
13. Vent
14. Crater
15...
moon,
IoIo is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of 3,642 kilometres, the fourth-largest moon in the Solar System. It was named after Io, a priestess of Hera who became one of the lovers of Zeus.With over 400 active volcanoes, Io is the most...
, are from various forms of molten, solid and gaseous sulfur. There is also a dark area near the
LunarThe Moon is Earth's only natural satellite and the fifth largest satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is , about thirty times the diameter of the Earth. The common centre of mass of the system is located at about —a quarter the Earth's...
craterIn the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
AristarchusAristarchus is a prominent lunar impact crater that lies in the northwest part of the Moon's near side. It is considered the brightest of the large formations on the lunar surface, with an albedo nearly double that of most lunar features. The feature is bright enough to be visible to the naked eye,...
that may be a sulfur deposit.
Sulfur is present in many types of
meteoriteA meteorite is a natural object originating in outer space that survives an impact with the Earth's surface. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...
s. Ordinary chondrites contain on average 2.1% sulfur, and carbonaceous chondrites may contain as much as 6.6%. Sulfur in meteorites is normally present as
troilitePyrrhotite is an unusual iron sulfide mineral with a variable iron content: FeS . The FeS endmember is known as troilite. Pyrrhotite is also called magnetic pyrite because the color is similar to pyrite and it is weakly magnetic. The magnetism increases as the iron content decreases, and...
(FeS), but other sulfides are found in some meteorites, and carbonaceous chondrites contain free sulfur, sulfates, and possibly other sulfur compounds.
Extraction from natural resources
Sulfur is extracted by mainly two processes: the Sicilian process and the
Frasch processThe Frasch process is a method to extract sulfur from underground deposits. Most of the world's sulfur was obtained this way until the late 20th century, when sulfur recovered from petroleum sources became more commonplace...
. The Sicilian process, which was first used in
SicilySicily is the largest island in the Mediterranean Sea. It is an autonomous region of Italy. Several much smaller islands surrounding it are considered to be part of Sicily....
, was used in ancient times to get sulfur from rocks present in volcanic regions. In this process, the sulfur deposits are piled and stacked in brick kilns built on sloping hillsides, and with airspaces between them. Then powdered sulfur is put on top of the sulfur deposit and ignited. As the sulfur burns, the heat melts the sulfur deposits, causing the molten sulfur to flow down the sloping hillside. The molten sulfur can then be collected in wooden buckets.
The second process used to obtain sulfur is the Frasch process. In this method, three concentric pipes are used: the outermost pipe contains superheated water, which melts the sulfur, and the innermost pipe is filled with hot compressed air, which serves to create foam and pressure. The resulting sulfur foam is then expelled through the middle pipe.
The Frasch process produces sulfur with a 99.5% purity content, and which needs no further purification. The sulfur produced by the Sicilian process must be purified by distillation.
Chemically
The
Claus processThe Claus process is the most significant gas desulfurizing process, recovering elemental sulfur from gaseous hydrogen sulfide. First patented in 1883 by the scientist Carl Friedrich Claus, the Claus process has become the industry standard....
is used to extract elemental sulfur from
hydrogen sulfideHydrogen sulfide is the chemical compound with the formula H
2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence....
produced in
hydrodesulfurizationHydrodesulfurization is a catalytic chemical process widely used to remove sulfur from natural gas and from refined petroleum products such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils...
of petroleum or from
natural gasNatural gas is a gas consisting primarily of methane. It is found associated with fossil fuels, in coal beds, as methane clathrates, and is created by methanogenic organisms in marshes, bogs, and landfills...
.
Biologically
In the biological route, hydrogen sulfide (H
2S) from natural gas or refinery gas is absorbed with a slight alkaline solution in a
wet scrubberWet scrubber is a form of pollution control technology. The term describes a variety of devices that remove pollutants from a furnace flue gas or from other gas streams...
, or the sulfide is produced by biological sulfate reduction. In the subsequent process step, the dissolved sulfide is biologically converted to elemental sulfur. This solid sulfur is removed from the reactor. This process has been built on commercial scale. The main advantages of this process are:
- no use of expensive chemicals,
- the process is safe as the H2S is directly absorbed in an alkaline solution,
- no production of a polluted waste stream,
- re-usable sulfur is produced, and
- the process occurs under ambient conditions.
The biosulfur product is different from other processes in which sulfur is produced because the sulfur is hydrophilic. Next to straightforward reuses as source for sulfuric acid production, it can also be applied as sulfur fertilizer.
Inorganic compounds
When dissolved in water, hydrogen sulfide is acidic and will react with metals to form a series of metal sulfides. Natural metal sulfides are common, especially those of iron. Iron sulfide is called
pyriteThe mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS
2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold due to its resemblance to gold...
, the so-called
fool's gold. Pyrite can show
semiconductorA semiconductor is a material that has an electrical resistivity between that of a conductor and an insulator, that is, generally in the range 10
3 Siemens/cm to 10
−8 S/cm. Devices made from semiconductor materials are the foundation of modern electronics, including radio,...
properties.
GalenaGalena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...
, a naturally occurring lead sulfide, was the first
semiconductorA semiconductor is a material that has an electrical resistivity between that of a conductor and an insulator, that is, generally in the range 10
3 Siemens/cm to 10
−8 S/cm. Devices made from semiconductor materials are the foundation of modern electronics, including radio,...
discovered and found a use as a signal
rectifierA rectifier is an electrical device that converts alternating current to direct current , a process known as rectification. Rectifiers have many uses including as components of power supplies and as detectors of radio signals...
in the cat's whiskers of early crystal radios.
Polymeric sulfur nitridePolythiazyl ,
x, was the first conducting inorganic polymer. In addition to being an electrical conductor, it was also found to be a superconductor at very low temperatures .-Structure and bonding:...
has metallic properties even though it does not contain any
metalA metal is a chemical element that is a good conductor of both electricity and heat, forms cations and ionic bonds with non-metals. In chemistry, a metal is an element, compound, or alloy characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive ions...
atoms. This compound also has unusual electrical and optical properties. This polymer can be made from
tetrasulfur tetranitrideTetrasulfur tetranitride is an inorganic compound with the formula S4N4. This gold-poppy coloured solid is the most important binary sulfur nitride, which are compounds that contain only the elements sulfur and nitrogen...
S
4N
4.
Phosphorus sulfides are useful in synthesis. For example, P
4S
10 and its derivatives
Lawesson's reagentLawesson's reagent, or LR, is a chemical compound used in organic synthesis as a thiation agent. Lawesson's reagent was first made popular by Sven-Olov Lawesson, who did not, however, invent it...
and
naphthalen-1,8-diyl 1,3,2,4-dithiadiphosphetane 2,4-disulfideA compound related to Lawesson's reagent named NpP
2S
4 has been formed by the reaction of 1-bromonaphthalene with P
4S
10, this is a 1,3,2,4-dithiadiphosphetane 2,4-disulfide which has a naphth-1,8-diyl group holding the two phosphorus atoms together...
are used to replace oxygen from some organic molecules with sulfur.
- Sulfide
A sulfide is a chemical compound containing sulfur in its lowest oxidation number of −2.- Properties :...
s (S2−), a complex family of compounds usually derived from S2−. Cadmium sulfideCadmium sulfide is a chemical compound with the formula CdS. Cadmium sulfide is yellow in colour and is a semiconductor. It exists in nature as two different minerals, hexagonal greenockite and cubic hawleyite. Cadmium sulfide is a direct band gap semiconductor and has many applications for...
(CdS) is an example.
- Sulfites (SO32−), the salts of sulfurous acid
Sulfurous acid is the chemical compound with the formula H2SO3. There is no evidence that sulfurous acid exists in solution, but the molecule has been detected in the gas phase...
(H2SO3) which is generated by dissolving SO2 in water. Sulfurous acid and the corresponding sulfites are fairly strong reducing agents. Other compounds derived from SO2 include the pyrosulfite or metabisulfite ion (S2O52−).
- Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
s (SO42−), the salts of sulfuric acidSulfuric acid, , is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry. World production in 2001 was 165 million tonnes, with an approximate value of US$8 billion...
. Sulfuric acid also reacts with SO3 in equimolar ratios to form pyrosulfuric acid (H2S2O7).
- Thiosulfates
Sodium thiosulfate , also spelled sodium thiosulphate, is a colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3•5H2O, an efflorescent, monoclinic crystalline substance also called sodium hyposulfite or “hypo.”The thiosulfate...
(S2O32−). Sometimes referred as thiosulfites or "hyposulfites", Thiosulfates are used in photographic fixing (HYPO) as reducing agents. Ammonium thiosulfate is being investigated as a cyanideA cyanide is any chemical compound that contains the cyano group , which consists of a carbon atom triple-bonded to a nitrogen atom. Inorganic cyanides are hydrogen cyanide salts in which cyanide is generally the anion CN
-. Organic compounds that have a -C≡N functional group bonded to...
replacement in leaching goldGold is a chemical element with the symbol Au and an atomic number of 79. It has been a highly sought-after precious metal for coinage, jewelry, and other arts since the beginning of recorded history. The metal occurs as nuggets or grains in rocks, in veins and in alluvial deposits. Gold is...
.http://doccopper.tripod.com/gold/AltLixiv.html
- Sodium dithionite
Sodium dithionite is a white crystalline powder with a weak sulfurous odor. Although it is stable under most conditions, it will decompose in hot water and in acid solutions...
, , is the highly reducing dianion derived from hyposulfurous/dithionous acid.
(Na
2S
2O
6).
- Polythionic acids (H2SnO6), where n can range from 3 to 80.
- Peroxymonosulfuric acid
Peroxymonosulfuric acid, also known as persulfuric acid, peroxysulfuric acid, or as Caro's acid, is H2SO5, a liquid at room temperature...
(H2SO5) and peroxydisulfuric acidPeroxydisulfuric is a sulfur oxoacid with the chemical formula H2S2O8 . In structural terms it can be written HO3SOOSO3H. It is one of a group of sulfur oxoacids, its salts, commonly known as persulfates, are industrially important but the...
s (H2S2O8), made from the action of SO3 on concentrated H2O2Hydrogen peroxide is a very pale blue liquid, slightly more viscous than water, that appears colorless in dilute solution. It is a weak acid, has strong oxidizing properties, and is a powerful bleaching agent. It is used as a disinfectant, antiseptic, oxidizer, and in rocketry as a propellant...
, and H2SO4Sulfuric acid, , is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry. World production in 2001 was 165 million tonnes, with an approximate value of US$8 billion...
on concentrated H2O2 respectively.
- Sodium polysulfides (Na2Sx)
- Sulfur hexafluoride
Sulfur hexafluoride is an inorganic, colorless, odorless, non-toxic and non-flammable gas . has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom. It is a hypervalent molecule. Typical for a nonpolar gas, it is poorly soluble in water but soluble in...
, SF6, a dense gas at ambient conditions, is used as nonreactive and nontoxic propellant
- Sulfur nitrides are chain and cyclic compounds containing only S and N. Tetrasulfur tetranitride
Tetrasulfur tetranitride is an inorganic compound with the formula S4N4. This gold-poppy coloured solid is the most important binary sulfur nitride, which are compounds that contain only the elements sulfur and nitrogen...
S4N4 is an example.
- Thiocyanate
Thiocyanate is the anion [SCN]
− and the conjugate base of thiocyanic acid. Common compounds include the colourless salts potassium thiocyanate and sodium thiocyanate. Organic compounds containing the functional group SCN are also called thiocyanates...
s contain the SCN− group. Oxidation of thiocyanoate gives thiocyanogenThiocyanogen, 2, is a pseudohalogen derived from the pseudohalide thiocyanate, [SCN]−. This hexatomic compound exhibits C2 point group symmetry and has the connectivity NCS-SCN...
, (SCN)2 with the connectivity NCS-SCN.
Organic compounds
Many of the unpleasant odors of organic matter are based on sulfur-containing compounds such as
methyl mercaptanThe ability to detect the presence of methanethiol is also a genetic trait, and these traits are inherited separately. There is only one genetic trait mentioned. "Also" and "these" imply more than one genetic trait....
and dimethyl sulfide. Thiols and sulfides are used in the odoration of natural gas, notably, 2-methyl-2-propanethiol (t-butyl mercaptan). The odor of
garlicAllium sativum, commonly known as garlic, is a species in the onion family Alliaceae. Its close relatives include the onion, shallot, leek, and chive. Garlic has been used throughout recorded history for both culinary and medicinal purposes. It has a characteristic pungent, spicy flavor that...
and "
skunkSkunks are mammals best known for their ability to secrete a liquid with a strong, foul-smelling odor. General appearance ranges from species to species, from black-and-white to brown or cream colored. Skunks belong to the family Mephitidae and to the order Carnivora...
stink" are also caused by sulfur-containing organic compounds. Not all organic sulfur compounds smell unpleasant; for example,
grapefruit mercaptanGrapefruit mercaptan is the common name for a natural organic compound found in grapefruit. It is a monoterpenoid that contains a thiol functional group. Structurally a hydroxy group of terpineol is replaced by the thiol in grapefruit mercaptan, so it also called thioterpineol...
, a sulfur-containing
monoterpenoidTerpenes are a large and varied class of hydrocarbons, produced primarily by a wide variety of plants, particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit terpenes from their osmeterium....
is responsible for the characteristic scent of grapefruit. It should be noted that this thiol is present in very low concentrations. In larger concentrations, the odor of this compound is that typical of all thiols, unpleasant.
Sulfur-containing organic compounds include the following (R, R', and R
are organic groups such as CH3):
- Thioether
A thioether is a functional group in organic chemistry that has the structure R1-S-R2 as shown on right. Like many other sulfur-containing compounds, volatile thioethers characteristically have foul odors....
s have the form
R
-S-R′. These compounds are the sulfur equivalents of
etherEther is a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...
s.
SulfoniumA sulfonium ion, also known as sulphonium ion and sulfanium ion, is a positively charged sulfur ion carrying three alkyl groups as substituents...
ions have the formula RR'S-'R'", i.e. where three groups are attached to the cationic sulfur center. DimethylsulfoniopropionateDimethylsulfoniopropionate , is a metabolite found in marine phytoplankton, seaweeds and some species of terrestrial and aquatic vascular plants. Older scientific literature refers to it as dimethyl-β-propiothetin...
(DMSP; (CH3)2S+CH2CH2COO−) is a sulfonium ion, which is important in the marine organic sulfur cycleSulfur is one of the constituents of many proteins, vitamins and hormones. It recycles as in other biogeochemical cycles.The essential steps of the sulfur cycle are:...
.
ThiolIn organic chemistry, a thiol is a compound that contains the functional group composed of a sulfur-hydrogen bond . Being the sulfur analogue of an alcohol group , this functional group is referred to either as a thiol group or a sulfhydryl group...
s (also known as mercaptans) have the form R-SH. These are the sulfur equivalents of alcoholIn chemistry, an alcohol is any organic compound in which a hydroxyl group is bound to a carbon atom of an alkyl or substituted alkyl group. An important group of acohols is formed by the simple acyclic alcohols, the general formula for which is C
nH
2n+1OH...
s.
Thiolates ions have the form R-S-. Such anions arise upon treatment of thiolIn organic chemistry, a thiol is a compound that contains the functional group composed of a sulfur-hydrogen bond . Being the sulfur analogue of an alcohol group , this functional group is referred to either as a thiol group or a sulfhydryl group...
s with base.
SulfoxideA sulfoxide is a chemical compound containing a sulfinyl functional group attached to two carbon atoms. Sulfoxides can be considered as oxidized sulfides...
s have the form R-S(=O)-R′. The simplest sulfoxide, DMSODimethyl sulfoxide is the chemical compound with the formula
2SO. It was first synthesized in 1866 by the Russian scientist Alexander Zaytsev, who reported his findings in a German chemistry journal in 1867...
, is a common solvent.
SulfoneA sulfone is a chemical compound containing a sulfonyl functional group attached to two carbon atoms. The central sulfur atom is twice double bonded to oxygen and has two further hydrocarbon substituents. The general structural formula is R-S-R' where R and R' are the organic groups. The use of...
s have the form R-S(=O)2-R′. A common sulfone is sulfolane C4H8SO2.
See also Category: sulfur compounds and organosulfur chemistry
Applications
One of the direct uses of sulfur is in
vulcanizationVulcanization or vulcanisation refers to a specific curing process of rubber involving high heat and the addition of sulfur or other equivalent curatives. It is a chemical process in which polymer molecules are linked to other polymer molecules by atomic bridges composed of sulfur atoms or carbon...
of rubber, where
polysulfidePolysulfides are a class of chemical compounds containing chains of sulfur atoms. The two main classes of polysulfides are anions with the general formula Sn2−. These anions are the conjugate bases of the hydrogen polysulfides H2Sn...
s crosslink organic polymers. Sulfur is a component of
gunpowderGunpowder, also called black powder, is a mixture of sulfur, charcoal, and potassium nitrate. It burns rapidly, producing volumes of hot solids and gases which can be used as a propellant in firearms and as a pyrotechnic composition in fireworks. The term gunpowder also refers broadly to any...
. It reacts directly with methane to give
carbon disulfideCarbon disulfide is a colorless, volatile liquid with the formula CS2. The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non-polar solvent...
, which is used to manufacture
cellophaneCellophane is a thin, transparent sheet made of regenerated cellulose. Its low permeability to air, oils, greases, and bacteria makes it useful for food packaging...
and
rayonRayon is a manufactured regenerated cellulose fiber. Because it is produced from naturally occurring polymers, it is neither a truly synthetic fiber nor a natural fiber; it is a semi-synthetic fiber. Rayon is known by the names viscose rayon and art silk in the textile industry. It usually has a...
.
Elemental sulfur is mainly used as a precursor to other chemicals. Approximately 85% (1989) is converted to
sulfuric acidSulfuric acid, , is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry. World production in 2001 was 165 million tonnes, with an approximate value of US$8 billion...
(
HHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H
2...
2S
OOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
4), which is of such prime importance to the
world's economiesThe world economy can be evaluated in various ways, depending on the model used, and this valuation can then be represented in various ways...
that the production and consumption of sulfuric acid is an indicator of a nation's industrial development. For example, more sulfuric acid is produced in the United States every year than any other industrial chemical. The principal use for the acid is the extraction of phosphate ores for the production of fertilizer manufacturing. Other applications of sulfuric acid include oil refining, wastewater processing, and mineral extraction.
Sulfur compounds are also used in detergents,
fungicideFungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
s, dyestuffs, and agrichemicals. In silver-based
photographyPhotography is the process, activity and art of creating still or moving pictures by recording radiation on a sensitive medium, such as a photographic film, or an electronic sensor...
sodium and ammonium
thiosulfateSodium thiosulfate , also spelled sodium thiosulphate, is a colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3•5H2O, an efflorescent, monoclinic crystalline substance also called sodium hyposulfite or “hypo.”The thiosulfate...
are used as "fixing agents."
Sulfur is an ingredient in some
acneAcne is a group of skin rashes that have different causes.* Acne vulgaris - most commonly experienced around puberty, typically of the face and shoulders/chest* Cystic acne, a severe form of acne wherein small cysts form...
treatments.
http://www.drugs.com/cdi/pernox-lotion.html
An increasing application is as fertilizer. Standard sulfur is hydrophobic and therefore has to be covered with a surfactant by bacteria in the ground before it can be oxidized to sulfate. This makes it a slow release fertilizer, which cannot be taken up by the plants instantly, but has to be oxidized to sulfate over the growth season. Sulfur also improves the use efficiency of other essential plant nutrients, particularly nitrogen and phosphorus. Biologically produced sulfur particles are naturally hydrophilic due to a biopolymer coating. This sulfur is therefore easier to disperse over the land (via spraying as a diluted slurry), and results in a faster release.
SulfiteSulfites are compounds that contain the sulfite ion SO . The sulfite ion is the conjugate base of sulfurous acid. Although the acid itself is elusive, its salts are widely used.-Structure:...
s, derived from burning sulfur, are heavily used to bleach
paperPaper is thin material mainly used for writing upon, printing upon or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
. They are also used as preservatives in dried
fruitThe term fruit has different meanings dependent on context, and the term is not synonymous in food preparation and biology. Fruits are the means by which flowering plants disseminate seeds, and the presence of seeds indicates that a structure is most likely a fruit, though not all seeds come from...
.
Magnesium sulfateMagnesium sulfate is a chemical compound containing magnesium and sulfur, with the formula MgSO4. In its hydrated form the pH is 6.0 . It is often encountered as the heptahydrate, MgSO4·7H2O, commonly called Epsom salt. Anhydrous magnesium sulfate is used as a...
, better known as Epsom salts, can be used as a
laxativeLaxatives are foods, compounds, or drugs taken to induce bowel movements or to loosen the stool, most often taken to treat constipation. Certain stimulant, lubricant, and saline laxatives are used to evacuate the colon for rectal and bowel examinations, and may be supplemented by enemas in that...
, a bath additive, an exfoliant, a
magnesiumMagnesium is a chemical element with the symbol Mg, atomic number 12 and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the earth's crust by mass, although ninth in the Universe as a whole...
supplement for plants, or a
desiccantA desiccant is a hygroscopic substance that induces or sustains a state of dryness in its local vicinity in a moderately well-sealed container....
.
Specialized applications
Sulfur is used as a light-generating medium in the rare lighting fixtures known as
sulfur lampThe sulfur lamp is a highly efficient full-spectrum electrodeless lighting system whose light is generated by sulfur plasma that has been excited by microwave radiation. The technology was developed in the early 1990s, but, although it appeared initially to be very promising, sulfur lighting was...
s.
Historical applications
In the late 18th century,
furnitureFurniture is the mass noun for the movable objects intended to support various human activities such as seating and sleeping in beds, to hold objects at a convenient height for work using horizontal surfaces above the ground, or to store things...
makers used molten sulfur to produce decorative
inlayInlay is a decorative technique of inserting pieces of contrasting, often coloured materials into depressions in a base object to form patterns or pictures that normally are flush with the matrix. In a wood matrix, inlays commonly use wood veneers, but other materials like shells, mother-of-pearl,...
s in their craft. Because of the
sulfur dioxideSulfur dioxide is the chemical compound with the formula SO
2. It is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide...
produced during the process of melting sulfur, the craft of sulfur inlays was soon abandoned. Molten sulfur is sometimes still used for setting steel bolts into drilled concrete holes where high shock resistance is desired for floor-mounted equipment attachment points. Pure powdered sulfur was also used as a medicinal tonic and laxative. Sulfur was also used in baths for people who had seizures.
Fungicide and pesticide
Sulfur is one of the oldest fungicides and pesticides. Dusting sulfur, elemental sulfur in powdered form, is a common fungicide for grapes, strawberry, many vegetables and several other crops. It has a good efficacy against a wide range of powdery mildew diseases as well as black spot. In organic production, sulfur is the most important fungicide. It is the only fungicide used in organically farmed apple production against the main disease
apple scabApple scab is a disease of apple trees caused by the ascomycete fungus Venturia inaequalis. The disease manifests as dull black or grey-brown lesions on the surface of tree leaves, buds or fruits. Lesions may also appear less frequently on the woody tissues of the tree. Fruits and the undersides...
under colder conditions. Biosulfur (biologically produced elemental sulfur with hydrophilic characteristics) can be used well for these applications.
Standard-formulation dusting sulfur is applied to crops with a sulfur duster or from a dusting plane. Wettable sulfur is the commercial name for dusting sulfur formulated with additional ingredients to make it water soluble. It has similar applications, and is used as a
fungicideFungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
against
mildewMildew refers to certain kinds of mold or fungus. In Old English, it meant honeydew , and later came to mean mildew in the modern sense....
and other mold-related problems with plants and soil.
Sulfur is also used as an "
organicOrganic farming is the form of agriculture that relies on crop rotation, green manure, compost, biological pest control, and mechanical cultivation etc.....
" (i.e. "green")
insecticideAn insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
(actually an acaricide) against
tickTick is the common name for the small arachnids in superfamily Ixodoidea that, along with other mites, constitute the Acarina. Ticks are ectoparasites , living by hematophagy on the blood of mammals, birds, and occasionally reptiles and amphibians...
s and
mitesMITES, or Minority Introduction to Engineering and Science, is a six-week summer program for rising high school seniors held at the Massachusetts Institute of Technology. Its purpose is to expose students from minority, or otherwise disadvantaged backgrounds, to the fields of science and engineering...
. A common method of use is to dust clothing or limbs with sulfur powder. Some
livestockLivestock are one or more domesticated animals raised in an agricultural setting to produce commodities such as food or fiber, or labor...
owners set out a sulfur salt block as a
salt lickA salt lick is a salt deposit that animals regularly lick. In an ecosystem, salt/mineral licks often occur naturally, providing the sodium, calcium, iron, phosphorus and zinc required in the springtime for bone, muscle and other growth in deer and other wildlife, such as moose, elephants, cattle,...
.
Biological role
See
sulfur cycleSulfur is one of the constituents of many proteins, vitamins and hormones. It recycles as in other biogeochemical cycles.The essential steps of the sulfur cycle are:...
for more on the inorganic and organic natural transformations of sulfur.
Sulfur is an essential component of all living
cellsThe cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos...
.
Inorganic sulfur forms a part of
iron-sulfur clusterFor biological Fe-S clusters, see iron-sulfur proteins.Iron-sulfur clusters are ensembles of iron and sulfide centres. Fe-S clusters are most often discussed in the context of the biological role for iron-sulfur proteins. Many Fe-S clusters are known in the area of organometallic chemistry and as...
s, and sulfur is the bridging ligand in the
CuCopper is a chemical element with the symbol Cu and atomic number 29.It is a ductile metal with very high thermal and electrical conductivity. Pure copper is rather soft and malleable and a freshly-exposed surface has a pinkish or peachy color...
A site of
cytochrome c oxidaseThe enzyme cytochrome c oxidase or Complex IV is a large transmembrane protein complex found in bacteria and the mitochondrion.It is the last enzyme in the respiratory electron transport chain of mitochondria located in the mitochondrial membrane...
, a basic substance involved in utilization of oxygen by all aerobic life.
Sulfur may also serve as chemical food source for some primitive organisms: some forms of bacteria use
hydrogen sulfideHydrogen sulfide is the chemical compound with the formula H
2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence....
(H
2S) in the place of water as the
electronAn electron is a subatomic particle that carries a negative electric charge. It has no known substructure and is believed to be a point particle. An electron has a mass that is approximately 1836 times less than that of the proton. The intrinsic angular momentum of the electron is a half integer...
donor in a primitive
photosynthesisPhotosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of Bacteria, but not in Archaea...
-like process in which oxygen is the electron receptor. The
photosyntheticPhotosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of Bacteria, but not in Archaea...
green and purple sulfur
bacteriaThe bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
and some chemolithotrophs use elemental oxygen to carry out such oxidization of hydrogen sulfide to produce elemental sulfur (S
o), oxidation state = 0. Primitive bacteria which live around deep ocean volcanic vents oxidize hydrogen sulfide in this way with oxygen: see
giant tube wormGiant tube worms, Riftia pachyptila, are marine invertebrates in the phylum Annelida related to tubeworms commonly found in the intertidal and pelagic zones...
for an example of large organisms (via bacteria) making metabolic use of hydrogen sulfide as food to be oxidized.
The so-called sulfur bacteria, by contrast, "breathe sulfate" instead of oxygen. They use sulfur as the electron acceptor, and reduce various oxidized sulfur compounds back into sulfide, often into hydrogen sulfide. They also can grow on a number of other partially oxidized sulfur compounds (e. g. thiosulfates, thionates, polysulfides, sulfites). The hydrogen sulfide produced by these bacteria is responsible for the smell of some intestinal gases and decomposition products.
Sulfur is a part of many bacterial defense molecules. For example, though sulfur is not a part of the
lactamA lactam is a cyclic amide. Prefixes indicate how many carbon atoms are present in the ring: β-lactam , γ-lactam , δ-lactam...
ring, it is a part of most beta lactam antibiotics, including the
penicillinPenicillin is a group of antibiotics derived from Penicillium fungi. Penicillin antibiotics are historically significant because they are the first drugs that were effective against many previously serious diseases such as syphilis and Staphylococcus infections...
s, cephalosporins, and monobactams.
Sulfur is absorbed by
plantPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
s via the
rootIn vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s from soil as the
sulfateIn inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
ionAn ion is an atom or molecule where the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge...
and reduced to sulfide before it is incorporated into
cysteineCysteine is an α-amino acid with the chemical formula HO
2CCHCH
2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is nonpolar and thus cysteine is usually classified as...
and other organic sulfur compounds (see
sulfur assimilationSulfur is an essential element for growth and physiological functioning of plants, however, its content strongly varies between plant species and it ranges from 0.1 to 6 % of the plants' dry weight. Sulfate taken up by the roots is the major sulfur source for growth, though it has to be reduced to...
for details of this process).
Sulfur is regarded as secondary nutrient although plant requirements for sulfur are equal to and sometimes exceed those for phosphorus. However sulfur is recognized as one of the major nutrients essential for plant growth, root nodule formation of legumes and plants protection mechanisms. Sulfur deficiency has become widespread in many countries in Europe. Because atmospheric inputs of sulfur will continue to decrease, the deficit in the sulfur input/output is likely to increase, unless sulfur fertilizers are used.
In plants and animals the
amino acidAmino acids are molecules containing an amine group, a carboxylic acid group and one of the twenty R-groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H
2NCHRCOOH, where R is an organic substituent...
s
cysteineCysteine is an α-amino acid with the chemical formula HO
2CCHCH
2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is nonpolar and thus cysteine is usually classified as...
and
methionineMethionine is an α-amino acid with the chemical formula HO
2CCHCH
2CH
2SCH
3. This essential amino acid is classified as nonpolar.-Function:...
contain sulfur, as do all polypeptides,
proteinProteins are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer chain are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues...
s, and
enzymeEnzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at...
s which contain these amino acids.
HomocysteineHomocysteine is an amino acid with the formula HSCH2CH2CHCO2H. It is a homologue of the amino acid cysteine, differing by an additional methylene group. It is biosynthesized from methionine by the removal of its terminal Cε methyl group...
and
taurineTaurine, or 2-aminoethanesulfonic acid, is an organic acid. It is also a major constituent of bile and can be found in the lower intestine and in small amounts in the tissues of many animals, including humans. Taurine is a derivative of the sulfur-containing amino acid, cysteine...
are other sulfur-containing acids which are similar in structure, but which are not coded for by
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
, and are not part of the
primary structureIn biochemistry, the primary structure of a biological molecule is the exact specification of its atomic composition and the chemical bonds connecting those atoms...
of proteins.
GlutathioneGlutathione is a tripeptide. It contains an unusual peptide linkage between the amine group of cysteine and the carboxyl group of the glutamate side chain. Glutathione, an antioxidant, helps protect cells from reactive oxygen species such as free radicals and peroxides...
is an important sulfur-containing tripeptide which plays a role in cells as a source of chemical reduction potential in the cell, through its sulfhydryl (-SH) moiety. Many important cellular enzymes use prosthetic groups ending with -SH moieties to handle reactions involving acyl-containing biochemicals: two common examples from basic metabolism are
coenzyme ACoenzyme A is a coenzyme, notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle...
and alpha-lipoic acid.
Disulfide bondIn chemistry, a disulfide bond is a covalent bond, usually derived by the coupling of two thiol groups. The linkage is also called an SS-bond or disulfide bridge. The overall connectivity is therefore C-S-S-C. The terminology is widely used in biochemistry...
s (S-S bonds) formed between cysteine residues in peptide chains are very important in protein assembly and structure. These strong covalent bonds between peptide chains give proteins a great deal of extra toughness and resiliency. For example, the high strength of feathers and hair is in part due to their high content of S-S bonds and their high content of cysteine and sulfur (eggs are high in sulfur because large amounts of the element are necessary for feather formation). The high disulfide content of hair and feathers contributes to their indigestibility, and also their odor when burned.
Traditional medical role for elemental sulfur
In traditional medical skin treatment which predates modern era of scientific medicine, elemental sulfur has been used mainly as part of creams to alleviate various conditions such as psoriasis, eczema and acne. The mechanism of action is not known, although elemental sulfur does oxidize slowly to sulfurous acid, which in turn (through the action of
sulfiteSulfites are compounds that contain the sulfite ion SO . The sulfite ion is the conjugate base of sulfurous acid. Although the acid itself is elusive, its salts are widely used.-Structure:...
) acts as a mild reducing and antibacterial agent.
Precautions
Elemental sulfur is non-toxic, but it can burn as an oxidizer or a reducing agent, producing combustion products that are toxic, such as
carbon disulfideCarbon disulfide is a colorless, volatile liquid with the formula CS2. The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non-polar solvent...
,
carbon oxysulfideCarbonyl sulfide is the chemical compound with the formula OCS. Commonly written as COS, it is a colourless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl group double bonded to a sulfur atom...
,
hydrogen sulfideHydrogen sulfide is the chemical compound with the formula H
2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence....
, and
sulfur dioxideSulfur dioxide is the chemical compound with the formula SO
2. It is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide...
.
Although
sulfur dioxideSulfur dioxide is the chemical compound with the formula SO
2. It is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide...
is sufficiently safe to be used as a
food additiveFood additives are substances added to food to preserve flavour or improve its taste and appearance.Some additives have been used for centuries; for example, preserving food by pickling , salting, as with bacon, preserving sweets or using sulfur dioxide as in some wines...
in small amounts, at high concentrations it reacts with moisture to form
sulfurous acidSulfurous acid is the chemical compound with the formula H2SO3. There is no evidence that sulfurous acid exists in solution, but the molecule has been detected in the gas phase...
which in sufficient quantities may harm the lungs, eyes or other
tissuesTissue is a cellular organizational level intermediate between cells and a complete organism. Hence, a tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function...
. In organisms without lungs such as insects or plants, it otherwise prevents
respirationIn animal physiology, respiration is the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...
.
Hydrogen sulfideHydrogen sulfide is the chemical compound with the formula H
2S. This colorless, toxic and flammable gas is partially responsible for the foul odor of rotten eggs and flatulence....
is toxic. Although very pungent at first, it quickly deadens the sense of smell, so potential victims may be unaware of its presence until death or other symptoms occur.
Sulfur trioxideSulfur trioxide is the chemical compound with the formula SO3. In the gaseous form, this species is a significant pollutant, being the primary agent in acid rain...
, a volatile liquid at standard temperature and pressure, is extremely dangerous, especially in contact with water, which reacts with it to form
sulfuric acidSulfuric acid, , is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry. World production in 2001 was 165 million tonnes, with an approximate value of US$8 billion...
with the generation of much heat. Sulfuric acid poses extreme hazards to many objects and substances.
Environmental impact
The burning of
coalCoal is a readily combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
and/or
petroleumPetroleum or crude oil is a naturally occurring, flammable liquid found in rock formations in the Earth consisting of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds.The term "petroleum" was first used in the treatise De Natura Fossilium, published in...
by industry and power plants generates
sulfur dioxideSulfur dioxide is the chemical compound with the formula SO
2. It is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide...
(S
OOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
2), which reacts with atmospheric water and oxygen to produce
sulfuric acidSulfuric acid, , is a strong mineral acid. It is soluble in water at all concentrations. Sulfuric acid has many applications, and is one of the top products of the chemical industry. World production in 2001 was 165 million tonnes, with an approximate value of US$8 billion...
(H
2SO
4). This sulfuric acid is a component of
acid rainAcid rain is rain or any other form of precipitation that is unusually acidic, i.e. elevated levels of hydrogen ions . It has harmful effects on plants, aquatic animals, and infrastructure. Acid rain is mostly caused by emissions of compounds of sulfur, nitrogen, and carbon which react with the...
, which lowers the
pHpH is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations...
of
soilSoil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics. It is composed of particles of broken rock that have been altered by chemical and...
and freshwater bodies, sometimes resulting in substantial damage to the
environmentThe biophysical environment is the symbiosis between the physical environment and the biological life forms within the environment, and includes all variables that comprise the Earth's biosphere. The biophysical environment can be divided into two categories: the natural environment and the built...
and chemical weathering of statues and structures. Fuel standards increasingly require sulfur to be extracted from
fossil fuelFossil fuels or mineral fuels are fuels formed by natural resources such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...
s to prevent the formation of acid rain. This extracted sulfur is then refined and represents a large portion of sulfur production. In coal fired power plants, the flue gases are sometimes purified. In more modern power plants that use syngas the sulfur is extracted before the gas is burned.
See also
- Sulfur cycle
Sulfur is one of the constituents of many proteins, vitamins and hormones. It recycles as in other biogeochemical cycles.The essential steps of the sulfur cycle are:...
- Stratospheric sulfur aerosols
Stratospheric sulfur aerosols are tiny sulfur-rich particles of solid or liquid, or a mixture of the two, which exist in the stratosphere region of the Earth's atmosphere...
- Disulfide bond
In chemistry, a disulfide bond is a covalent bond, usually derived by the coupling of two thiol groups. The linkage is also called an SS-bond or disulfide bridge. The overall connectivity is therefore C-S-S-C. The terminology is widely used in biochemistry...
- Sulfonium
A sulfonium ion, also known as sulphonium ion and sulfanium ion, is a positively charged sulfur ion carrying three alkyl groups as substituents...
S+, S+R3
- Ultra-low sulfur diesel
Ultra-low sulfur diesel is a term used to describe a standard for defining diesel fuel with substantially lowered sulfur contents...
- Claus process
The Claus process is the most significant gas desulfurizing process, recovering elemental sulfur from gaseous hydrogen sulfide. First patented in 1883 by the scientist Carl Friedrich Claus, the Claus process has become the industry standard....
- Shell-Paques sulfide removal/sulfur recovery process
External links