Boron – Its Compounds & Applications
Boron is an amazing element whose uses are diverse and effective. From keeping plants and animals healthy to providing a powerful decarbonization option, borates – the boron compounds can be found naturally all around us, making it incredibly accessible for many applications.
Boron occurs in the form of borates in the oceans, coal, sedimentary rocks, and some soils. It is a semimetal of main Group 13. It is abundant in nature, with 10 mg/kg concentrations in the Earth’s crust and about 4.5 mg/liter in the ocean. It is indispensable for plant growth and has wide industrial and agricultural applications.
The most important commercial borate products and minerals are borax pentahydrate, borax, sodium perborate, boric acid, colemanite, and ulexite.
Borax pentahydrate (Na2B4O7·5H2O), also known under various aliases such as Borax 5 Mol or Sodium Tetraborate, is an incredible substance made up of white crystalline granules. The insulation industry is most commonly employed to strengthen glass fiber materials, while ceramics utilize its high water solubility for glazing purposes. Its exceptional protection from the heat also makes it useful within non-ferrous metal sectors; when melted under extreme temperatures, borax pentahydrate creates an incredibly smooth liquid that acts like a protective slag former and fusing accelerator.
The compound of sodium tetraborate with water (NaBO·xH20) is commonly known as borax or sodium olefin. It can be obtained by acidifying an aqueous solution containing it, which then evolves hydrogen gas due to the interaction between these two materials. Borates are alkaline enough for pH balancing without lowering the base concentration. It is widely used as an agricultural pesticide or herbicide and is found in household products like detergents, bleach, paint, leather, and other cleaning agents. Borax-based ultra-high-strength steel has been discovered to make automobiles lighter and less prone to corrosion. At the same time, ceramic frits created with borax aid in making tough glazes on tiles, roofs, silos, appliances, etc. For soldering or welding, it is utilized as flux.
Sodium perborate is a versatile chemical compound with various uses. Its molecular formula, NaBO3·nH2O, and forms can be encountered as anhydrous or hexahydrates when crystallized. These salts are odorless white solids that easily dissolve in water to produce granular nuggets known as sodium metaborates upon being pulverized at 100 Celsius using fluid-bed reactors – the oldest type of bleaching agent. It also has anti-microbial properties, which makes it ideal for ophthalmic medicines for dry eyes, forensic applications, and disinfecting use. Since 2004, Health Canada has licensed perboric acid in the form of sodium perborate for use as a disinfectant for medical devices.
Boric acid, also known as hydrogen borate or orthoboric acid, is a naturally occurring mineral found in rocks, soil plants, and streams. It’s most commonly used to control pests such as insects, spiders, and mites, but it can also act as a fertilizer for plants and a preservative for wood products. Found in concentrations ranging from 1-100%, Boric acid has industrial uses like sewage systems management and uses within cosmetics, lotions, soaps & more. Products that contain this ingredient have been registered domestically (in America) since 1948.
Colemanite (Ca2B6O11·5H2O) is hydrated calcium borate, an altered variation of borax. Over 200 minerals contain boron, but only colemanite has been commercially important due to its 50% B2O3 content which ultimately makes it useful for the manufacturing industry, oil refining revitalization, detergents, and textiles industry, etc. It is a popular mineral among collectors. It forms at lower pHs and warmer temperatures than other similar compounds like ulexite. Colemanite is found all over the world, especially near granite rocks.
Ulexite (NaCaB5O6(ΟH)6·5H2O) is a mineral that consists of hydrated sodium and calcium borates. Individual crystals are colorless, but they can form into more common nodular or lenslike aggregates (often resembling cotton balls) to give off a white luster like silk. Ulexites are useful for their fiber-optic properties; this property led it to be called “television rock.” Ulexite fibers are optical fibers transporting light along their lengths by internal reflection. A good-quality specimen of ulexite will exhibit an image of whichever surface is next to its opposite side when cut with flat polished sides perpendicular to the direction of the fibers. Ulexite is rare but may be derived from boron leached out of sediments and pyroclastic rocks by flowing waters.
It exists in different forms, the most common of which is amorphous boron, a dark powder. At standard temperatures, boron is a poor electrical conductor but is a good conductor at high temperatures. It doesn’t react to oxygen, water, acids, and alkalis, but it reacts with metals to form borides.
How is Boron Extracted and Prepared?
Boron occurs combined as borax, kernite, and tincalconite (hydrated sodium borates), the major commercial boron minerals, especially concentrated in the arid regions of California, and as widely dispersed minerals such as colemanite, ulexite, and tourmaline. The most important source of boron is rasorite, located in the Mojave Desert in California. Sassolite—natural boric acid—occurs, especially in Italy. Boron occurs as an orthoboric acid in some volcanic spring waters and as borates in the minerals borax and colemanite. Major borax deposits can be found in Turkey.
Pure boron is prepared by reducing boron trichloride or tribromide with hydrogen on electrically heated filaments. Impure, or amorphous, boron can be prepared by heating the trioxide with magnesium powder.
Properties of Boron
Pure crystalline boron is a black, lustrous semiconductor; i.e., it conducts electricity like a metal at high temperatures and is almost an insulator at low temperatures. It is hard enough to scratch some abrasives, such as carborundum, but too brittle for tool use. It absorbs radiation very well. It constitutes about 0.001 percent by weight of Earth’s crust.
As stated in britannica.com, pure boron exists in at least four allotropes. Closed cages containing 12 boron atoms arranged in the form of an icosahedron occur in the various crystalline forms of elemental boron. Crystalline boron is almost inert chemically at ordinary temperatures. Boiling hydrochloric acid does not affect it, and hot concentrated nitric acid only slowly converts finely powdered boron to boric acid (H3BO3). Boron exhibits non-metallic characteristics.
Applications of Boron
Boron serves a variety of purposes in multiple fields:
Boron is increasingly recognized as a vital mineral for human health. It plays important roles in many bodily processes, including maintaining healthy bones and joints, improving cognitive function, managing inflammation, and more in healthcare, boron supplements treatments for conditions such as osteoporosis and arthritis. As research into its health benefits continues to expand, it is becoming clear that this element could be useful in various medical treatments. One major area of research involves using boron to create targeted drug therapies. The element has been found to bind with certain proteins on cells, allowing drugs or other compounds to be delivered directly to diseased cells without harming surrounding healthy tissue. This could have far-reaching implications for treating conditions like cancer and other diseases.
Boron has a variety of uses for improving sustainability and helping combat climate change. Not only can it be used to reduce the carbon intensity of industrial emissions, but also, when mixed with coal or other fuels, it helps lower greenhouse gas emission levels.
Borates are also an essential ingredient in renewable energy sources like LED lights powered by solar, wind, or hydropower, as well as components necessary for building nuclear power plants and operating turbines/panels; all aiding in reducing dependence on traditional fuel sources while saving money on utility bills.
Boron is an essential micronutrient for plant health and growth, integral to building cell walls and reproductive structures. Without enough, the crops can suffer from empty pollen grains, weak vitality, and reduced numbers of flowers per plant; stunting or rough leaves may also occur with interveinal chlorosis on the leaf blades indicative of a deficiency.
Not only that, but by helping maintain root membrane function and structure, it improves the uptake of other important nutrients such as phosphorus (P) ad potassium (K). Boron fertilizers play an invaluable role in sustainably increasing yields and safeguarding food security now and into the future too. In addition, its use extends to pesticides making this an incredible micronutrient with various applications.