It is a colorless crystalline solid that dissolves in water to make a basicsolution.
It is commonly available in powder or granular form and has many industrial and household uses, including as a pesticide, as a metal soldering flux, as a component of glass, enamel, and pottery glazes, for tanning of skins and hides, for artificial aging of wood, as a preservative against wood fungus, and as a pharmaceutic alkalizer. In chemical laboratories, it is used as a buffering agent.[1][8]
The terms tincal and tincar refer to native borax, historically mined from dry lake beds in various parts of Asia.[9]
History
Borax was first discovered in dry lake beds in Tibet. Native tincal from Tibet, Persia, and other parts of Asia was traded via the Silk Road to the Arabian Peninsula in the 8th century AD.[9]
The words tincal and tincar were adopted into English in the 17th century from Malaytingkal and from Urdu/Persian/Arabicتنکارtinkār/tankār; thus the two forms in English. These all appear to be related to the Sanskritटांकणṭānkaṇa.[14][15]
From the chemical perspective, borax contains the [B4O5(OH)4]2− ion. In this structure, there are two four-coordinate boron centers and two three-coordinate boron centers.
It is a proton conductor at temperatures above 21°C. Conductivity is maximum along the b-axis.[16]
Borax is also easily converted to boric acid and other borates, which have many applications. Its reaction with hydrochloric acid to form boric acid is:
Molten borax dissolves many metal oxides to form glasses. This property is important for its uses in metallurgy and for the borax bead test of qualitative chemical analysis.
Borax is soluble in a variety of solvents; however, it is notably insoluble in ethanol.[1]
The term borax properly refers to the so-called "decahydrate" Na2B4O7·10H2O, but that name is not consistent with its structure. It is actually octahydrate. The anion is not tetraborate[B4O7]2− but tetrahydroxy tetraborate[B4O5(OH)4]2−,[16] so the more correct formula should be Na2B4O5(OH)4·8H2O. However, the term may be applied also to the related compounds. Borax "pentahydrate" has the formula Na2B4O7·5H2O, which is actually a trihydrate Na2B4O5(OH)4·3H2O. It is a colorless solid with a density of 1.880kg/m3 that crystallizes from water solutions above 60.8°C in the rhombohedral crystal system. It occurs naturally as the mineral tinkhanite.[19] It can be obtained by heating the decahydrate above 61°C.[20] Borax "dihydrate" has the formula Na2B4O7·2H2O, which is actually anhydrous, with the correct formula Na2B4O5(OH)4. It can be obtained by heating the "decahydrate" or "pentahydrate" to above 116-120°C.[20] Anhydrous borax is sodium tetraborate proper, with formula Na2B4O7. It can be obtained by heating any hydrate to 300°C.[20] It has one amorphous (glassy) form and three crystalline forms – α, β, and γ, with melting points of 1015, 993 and 936 K respectively. α-Na2B4O7 is the stable form.[20]
Naturally occurring borax (known by the trade name Rasorite–46 in the United States and many other countries) is refined by a process of recrystallization.[22]
Borax is used in pest control solutions because it is toxic to ants and rats. Because it is slow-acting, worker ants will carry the borax to their nests and poison the rest of the colony.[23]
Borate ions (commonly supplied as boric acid) are used in biochemical and chemical laboratories to make buffers, e.g. for polyacrylamide gel electrophoresis of DNA and RNA, such as TBE buffer (borate buffered tris-hydroxymethylaminomethonium)[28][29] or the newer SB buffer or BBS buffer (borate buffered saline) in coating procedures. Borate buffers (usually at pH 8) are also used as preferential equilibration solutions in dimethyl pimelimidate (DMP) based crosslinking reactions.[citation needed]
Borax as a source of borate has been used to take advantage of the co-complexing ability of borate with other agents in water to form complex ions with various substances. Borate and a suitable polymer bed are used to chromatograph non-glycatedhemoglobin differentially from glycated hemoglobin (chiefly HbA1c), which is an indicator of long-term hyperglycemia in diabetes mellitus.
Borax alone does not have a high affinity for hardness cations, although it has been used for water-softening. Its chemical equation for water-softening is given below:
In artisanal gold mining, borax is sometimes used as part of a process known as the borax method (as a flux) meant to eliminate the need for toxic mercury in the gold extraction process, although it cannot directly replace mercury. Borax was reportedly used by gold miners in parts of the Philippines in the 1900s.[32][33] There is evidence that, in addition to reducing the environmental impact, this method achieves better gold recovery for suitable ores and is less expensive. This borax method is used in northern Luzon in the Philippines, but miners have been reluctant to adopt it elsewhere for reasons that are not well understood.[34] The method has also been promoted in Bolivia[35] and Tanzania.[36]
Borax, given the E numberE285, is used as a food additive but this use is banned in some countries, such as Australia, China, Thailand and the United States.[39] As a consequence, certain foods, such as caviar, produced for sale in the United States contain higher levels of salt to assist preservation.[40] In addition to its use as a preservative, borax imparts a firm, rubbery texture to food. In China, borax (Chinese:硼砂; pinyin:péng shā or Chinese:月石; pinyin:yuè shí) has been found in foods including wheat and rice noodles named lamian (Chinese:拉面; pinyin:lāmiàn), shahe fen (Chinese:沙河粉; pinyin:shāhéfěn), char kway teow (Chinese:粿條; pinyin:guǒ tiáo), and chee cheong fun (Chinese:肠粉; pinyin:chángfěn)[clarification needed][41] In Indonesia, it is a common, but forbidden,[42] additive to such foods as noodles, bakso (meatballs), and steamed rice. When consumed with boric acid, numerous studies have demonstrated a negative[clarification needed] association between borax and various types of cancers.[43] Boric acid and borax are low in toxicity for acute oral exposures, at approximately the same acute toxicity as salt. The average dose for asymptomatic ingestion cases, which accounts for 88% of all ingestions, is around 0.9 grams. However, the range of reported asymptomatic doses is wide, from 0.01 to 88.8 g.[44]
Pulverized for the prevention of stubborn pests (e.g. German cockroaches) in closets, pipe and cable inlets, wall panelling gaps, and inaccessible locations where ordinary pesticides are undesirable[49]
In particle physics as an additive to nuclear emulsion, to extend the latent image lifetime of charged particle tracks. The first observation of the pion, which was awarded the 1950 Nobel Prize, used this type of emulsion.[61][62]
Toxicity
According to one study, borax is not acutely toxic. Its LD50 (median lethal dose) score is tested at 2.66 g/kg in rats, meaning that a significant dose of the chemical is needed to cause severe symptoms or death. The lethal dose is not necessarily the same for humans. On pesticide information websites it is listed as a non-lethal compound and of no hazardous concerns.[citation needed]
Borax has been in use as an insecticide in the United States with various restrictions since 1946. All restrictions were removed in February 1986 due to the low toxicity of borax, as reported in two EPA documents relating to boric acid and borax.[63][64]
EPA has determined that, because they are of low toxicity and occur naturally, boric acid and its sodium salts should be exempted from the requirement of a tolerance (maximum residue limit) for all raw agricultural commodities.[63]
Although it cited inconclusive data, a re-evaluation in 2006 by the EPA still found that "There were no signs of toxicity observed during the study and no evidence of cytotoxicity to the target organ."[65] In the reevaluation, a study of toxicity due to overexposure was checked and the findings were that "The residential handler inhalation risks due to boric acid and its sodium salts as active ingredients are not a risk concern and do not exceed the level of concern..." but that there could be some risk of irritation to children inhaling it if used as a powder for cleaning rugs.
Overexposure to borax dust can cause respiratory irritation, while no skin irritation is known to exist due to external borax exposure. Ingestion may cause gastrointestinal distress including nausea, persistent vomiting, abdominal pain, and diarrhea. Effects on the vascular system and human brain include headaches and lethargy but are less frequent. In severe cases, a "beefy" red rash affecting the palms, soles, buttocks and scrotum has occurred.[66]
The Indonesian Directorate of Consumer Protection warns of the risk of liver cancer with high consumption of borax over a period of 5–10 years.[60]
Borax was added to the Substance of Very High Concern (SVHC) candidate list on December 16, 2010. The SVHC candidate list is part of the EU Regulations on the Registration, Evaluation, Authorisation and Restriction of Chemicals 2006 (REACH), and the addition was based on the revised classification of borax as toxic for reproduction category 1B under the CLP Regulations. Substances and mixtures imported into the EU which contain borax are now required to be labelled with the warnings "May damage fertility" and "May damage the unborn child".[67] It was proposed for addition to REACH Annex XIV by the ECHA on July 1, 2015.[68] If this recommendation is approved, all imports and uses of borax in the EU will have to be authorized by the ECHA.[needs update]
A review of the boron toxicity (as boric acid and borates) published in 2012 in the Journal of Toxicology and Environmental Health concluded: "It clearly appears that human B [boron] exposures, even in the highest exposed cohorts, are too low to reach the blood (and target tissue) concentrations that would be required to exert adverse effects on reproductive functions."[69] A draft risk assessment released by Health Canada in July 2016 has found that overexposure to boric acid has the potential to cause developmental and reproductive health effects. Since people are already exposed to boric acid naturally through their diets and water, Health Canada advised that exposure from other sources should be reduced as much as possible, especially for children and pregnant women.
The concern is not with any one product, but rather multiple exposures from a variety of sources. With this in mind, the department also announced that certain pesticides that contain boric acid, which are commonly used in homes, will have their registrations cancelled and be phased out of the marketplace. As well, new, more protective label directions are being introduced for other boric acid pesticides that continue to be registered in Canada (for example, enclosed bait stations and spot treatments using gel formulations).[70]
↑ It is also written as Na2B4O7·10H2O, which shows that it is a decahydrated tetraborate.
Related Research Articles
Boron is a chemical element. It has the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the boron group it has three valence electrons for forming covalent bonds, resulting in many compounds such as boric acid, the mineral sodium borate, and the ultra-hard crystals of boron carbide and boron nitride.
Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula B(OH)3. It may also be called hydrogen orthoborate, trihydroxidoboron or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolves in water, and occurs in nature as the mineral sassolite. It is a weak acid that yields various borate anions and salts, and can react with alcohols to form borate esters.
A borate is any of a range of boron oxyanions, anions containing boron and oxygen, such as orthoborate BO3−3, metaborate BO−2, or tetraborate B4O2−7; or any salt of such anions, such as sodium metaborate, Na+[BO2]− and borax (Na+)2[B4O7]2−. The name also refers to esters of such anions, such as trimethyl borate B(OCH3)3 but they are alkoxides.
Ulexite sometimes called TV rock or TV stone due to its unusual optical properties, is a hydrous borate hydroxide of sodium and calcium with the chemical formula NaCaB5O6(OH)6·5H2O. The mineral occurs as silky white rounded crystalline masses or in parallel fibers. Ulexite was named for the German chemist Georg Ludwig Ulex (1811–1883), who first discovered it.
Sodium hypochlorite is an alkaline inorganic chemical compound with the formula NaOCl. It is commonly known in a dilute aqueous solution as bleach or chlorine bleach. It is the sodium salt of hypochlorous acid, consisting of sodium cations and hypochlorite anions.
Diborane(6), commonly known as diborane, is the chemical compound with the formula B2H6. It is a highly toxic, colorless, and pyrophoric gas with a repulsively sweet odor. Given its simple formula, borane is a fundamental boron compound. It has attracted wide attention for its electronic structure. Several of its derivatives are useful reagents.
Copper(II) sulfate is an inorganic compound with the chemical formula CuSO4. It forms hydrates CuSO4·nH2O, where n can range from 1 to 7. The pentahydrate (n = 5), a bright blue crystal, is the most commonly encountered hydrate of copper(II) sulfate, while its anhydrous form is white. Older names for the pentahydrate include blue vitriol, bluestone, vitriol of copper, and Roman vitriol. It exothermically dissolves in water to give the aquo complex [Cu(H2O)6]2+, which has octahedral molecular geometry. The structure of the solid pentahydrate reveals a polymeric structure wherein copper is again octahedral but bound to four water ligands. The Cu(II)(H2O)4 centers are interconnected by sulfate anions to form chains.
Sodium sulfate (also known as sodium sulphate or sulfate of soda) is the inorganic compound with formula Na2SO4 as well as several related hydrates. All forms are white solids that are highly soluble in water. With an annual production of 6 million tonnes, the decahydrate is a major commodity chemical product. It is mainly used as a filler in the manufacture of powdered home laundry detergents and in the Kraft process of paper pulping for making highly alkaline sulfides.
Sodium borate is a generic name for any salt of sodium with an anion consisting of boron and oxygen, and possibly hydrogen, or any hydrate thereof. It can be seen as a hydrated sodium salt of the appropriate boroxy acid, although the latter may not be a stable compound.
Boron trifluoride is the inorganic compound with the formula BF3. This pungent, colourless, and toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds.
Tetrasodium pyrophosphate, also called sodium pyrophosphate, tetrasodium phosphate or TSPP, is an inorganic compound with the formula Na4P2O7. As a salt, it is a white, water-soluble solid. It is composed of pyrophosphate anion and sodium ions. Toxicity is approximately twice that of table salt when ingested orally. Also known is the decahydrate Na4P2O7· 10(H2O).
Boron trioxide or diboron trioxide is the oxide of boron with the formula B2O3. It is a colorless transparent solid, almost always glassy (amorphous), which can be crystallized only with great difficulty. It is also called boric oxide or boria. It has many important industrial applications, chiefly in ceramics as a flux for glazes and enamels and in the production of glasses.
In chemistry, tetraborate or pyroborate is an anion with formula B4O2−7; or a salt containing that anion, such as sodium tetraborate, Na2B4O7. It is one of the boron oxoacids, that is, a borate.
Sodium perborate is chemical compound whose chemical formula may be written NaH2BO4, Na2H4B2O8, or, more properly, [Na+]2[B2O4(OH)4]2−. Its name is sometimes abbreviated as PBS.
Tetrahydroxyborate is an inorganic anion with the chemical formula [BH4O4]− or [B(OH)4]−. It contributes no colour to tetrahydroxyborate salts. It is found in the mineral hexahydroborite, Ca(B(OH)4)2 · 2 H2O, originally formulated CaB2O4 · 6 H2O. It is one of the boron oxoanions, and acts as a weak base. The systematic names are tetrahydroxyboranuide (substitutive) and tetrahydroxidoborate(1−) (additive). It can be viewed as the conjugate base of boric acid.
Disodium octaborate is a borate of sodium, a chemical compound of sodium, boron, and oxygen — a salt with elemental formula Na2B8O13 or (Na+)2[B8O13]2−, also written as Na2O·4B2O3. It is a colorless crystalline solid, soluble in water.
Eti Maden is a Turkish state-owned mining and chemicals company focusing on boron products. It holds a government monopoly on the mining of borate minerals in Turkey, which possesses 72% of the world's known deposits. In 2012, it held a 47% share of global production of borate minerals, ahead of its main competitor, Rio Tinto Group, which held 23%.
Sodium metaborate is a chemical compound of sodium, boron, and oxygen with formula NaBO2. However, the metaborate ion is trimeric in the anhydrous solid, therefore a more correct formula is Na3B3O6 or (Na+)3[B3O6]3−. The formula can be written also as Na2O·B2O3 to highlight the relation to the main oxides of sodium and boron. The name is also applied to several hydrates whose formulas can be written NaBO2·nH2O for various values of n.
Allkem Limited, known as Orocobre Limited until 30 November 2021, is an Argentinian mining company that is a wholly-owned subsidiary of Arcadium Lithium. Headquartered in Buenos Aires, Argentina, Allkem's portfolio includes lithium brine operations in Argentina, a hard-rock lithium operation in Australia and a lithium hydroxide conversion facility in Japan. Allkem is dual listed on the Australian Securities Exchange and Toronto Stock Exchange. In May 2023, Allkem agreed terms to merge with Livent. In January 2024, Allkem and Livent merged to form the NYSE-listed Arcadium Lithium.
Trisodium borate is a chemical compound of sodium, boron, and oxygen, with formula Na3BO3, or (Na+)3[BO3]3−. It is a sodium salt of the orthoboric acid B(OH)3.
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↑ "American Borax Production". Scientific American. Vol.37, no.12. September 22, 1877. pp.184–185. JSTOR26062263.. The article states that the distance between Columbus, Nevada and Wadsworth, Nevada is "about 360 miles" whereas today the distance on modern roads is about 160 miles.
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↑ Wehr, Hans (1979). "بورق". In Cowan, J. Milton (ed.). A Dictionary of Modern Written Arabic (4thed.). Ithaca, NY: Spoken Language Services. p.100. ISBN0-87950-003-4.
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↑ Klotz, John H.; Greenberg, Les; Amrhein, Christopher; Rust, Michael K. (August 1, 2000). "Toxicity and Repellency of Borate-Sucrose Water Baits to Argentine Ants (Hymenoptera: Formicidae)". Journal of Economic Entomology. 93 (4): 1256–1258. doi:10.1603/0022-0493-93.4.1256. PMID10985039. S2CID17829851.
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↑ Peacock, Andrew C.; Dingman, C. Wesley (1967). "Resolution of Multiple Ribonucleic Acid Species by Polyacrylamide Gel Electrophoresis". Biochemistry. 6 (6): 1818–1827. doi:10.1021/bi00858a033. PMID6035921.
↑ "The borax method"(PDF). Borax replacing mercury in small-scale mining. The Geological Survey of Denmark and Greenland (GEUS). Archived from the original(PDF) on December 6, 2008. Retrieved August 2, 2008.
↑ "Caviar glossary". The Caviar Guide a gourmet review of caviars & fish roe. Hanson Ltd, Geneva, Switzerland. Archived from the original on December 8, 2008. Retrieved July 7, 2008.
↑ Suárez, Juan C. (2011), "Bioadhesives", in da Silva, Lucas F. M.; Öchsner, Andreas; Adams, Robert D. (eds.), Handbook of Adhesion Technology, Springer Berlin Heidelberg, pp.1385–1408, doi:10.1007/978-3-642-01169-6_53, ISBN978-3-642-01168-9
↑ Lattes, C.M.G.; Fowler, R.H.; Cuer, R. (1947). "Range-Energy Relation for Protons and a-Particles in the New Ilford 'Nuclear Research' Emulsions". Nature. 159: 301–302. doi:10.1038/159301a0.
↑ Bolt, Hermann M.; Başaran, Nurşen; Duydu, Yalçın (2012). "Human Environmental and Occupational Exposures to Boric Acid: Reconciliation with Experimental Reproductive Toxicity Data". Journal of Toxicology and Environmental Health, Part A. 75 (8–10): 508–514. Bibcode:2012JTEHA..75..508B. doi:10.1080/15287394.2012.675301. PMID22686310. S2CID31972554.
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