Boric acid, chemically represented as H3BO3, is a naturally occurring compound containing three elements - boron, hydrogen, and oxygen. The element boron doesn't exist by itself in nature. It combines with other elements, such as with sodium to form salts, and with oxygen to form boric acid.
Boric acid crystals are white in color. They are odorless, nearly tasteless, and appear similar to table salt in the granular form, and like talcum powder in the powdered form. The derivatives of boric acid, that is, the boron-containing oxyanions known as borates are most commonly found in the dried salt lake beds of deserts or arid regions.
Boric acid is found naturally in soil, rocks, and seawater. It is also present in many foods such as fruits, vegetables, and grains. So, an average person would be consuming some amount of it everyday through his/her diet.
The uses of this acid have been known to man for thousands of years. The Chinese have traditionally used it as a food preservative, cleansing agent, and as an antiseptic. It is also believed that they would use borax to glaze ceramic containers. The Arabs would use boric acid to preserve their gold and silver.
Boric acid crystals were first made by Wilhelm Homberg in 1702, and were soon found to be an effective eye wash and a mild antiseptic. Today, there are many uses of this mild acid, including medicinal, industrial treatments, and in pesticides. A few important ones among these are elaborated on in the following section.
Various Uses of Boric Acid
Boric acid is registered as an insecticide for controlling household pests like cockroaches, termites, fire ants, fleas, silverfish, and other insects.
Available in both gel and powder form, this acid can be dabbed on or sprinkled near sinks, counters, refrigerators, stoves, or in places where the infestation is more. It is also available in the form of aerosols, wettable powders, dust, and pellets.
It is usually used as an antiseptic for treating minor burns and cuts, since it inhibits the growth of micro-organisms in the body. Boric acid eye wash is considered to be an effective remedy for pink eye (conjunctivitis) and other eye infections.
It is also used in contact lens solutions and other eye disinfectants. Its anti-bacterial property allows it to be used in acne treatments and for the prevention of athlete's foot. Using it on yeast infections has been known to prevent candidiasis or vaginal yeast infections.
Fiberglass and Glass
It is widely used in the manufacturing of borosilicate and other heat-resistant glassware, to enhance the chemical composition, thereby improving the temperature resistance of glass. This enhanced glass is then used in halogen bulbs, ovenware, and microwavable glassware.
Boric acid is used in the optical glassware industry to increase the chemical resistance and durability of glass. It is also used to further enhance the properties of modern high-tech glass products and coating materials, such as those used in computer screens, LCDs, plasma screens, etc.
Flame Retardant and Corrosion Inhibitor
Since boron in boric acid is an effective flame retardant, it is used in an array of products like wood, plywood, textile products, cotton, paper and cellulose. In addition to this, boron is also used as a corrosion inhibitor and an antifreeze in brewing, heat treating, and in the treatment of metallic products.
Since the boric compounds significantly reduce the melting point and control the coefficient of the expansion, they ensure that the glaze remains fixed to the body without undergoing any distortion.
A very effective lubricant can be derived from boric acid by dissolving the colloidal suspensions of its nanoparticles in petroleum or vegetable oil. It has a coefficient of sliding friction which decreases as pressure increases to a value ranging from 0.10 to 0.02. making it useful for lubricating ceramic or metal surfaces.
Self-lubricating H3BO3 films are formed via a spontaneous chemical reaction between water molecules and B2O3 coatings in a humid environment.
Boric acid is also popularly used to lubricate carom and similar game boards, allowing for a much smoother and faster play. It reduces friction, thus increasing the life of the board's surface.
It is used in some nuclear power plants as a 'neutron poison', which reduces the probability of the occurrence of thermal fission by absorbing some of the thermal neutrons.
Natural boron comprises approximately 20% boron-10 and 80% boron-11 isotopes. Boron-10 is capable of absorbing low energy (thermal) neutrons. Thus, by raising the concentration of boric acid in a nuclear reactor's coolant, the probability of neutrons causing further fission reactions can be reduced and regulated.
Significantly, after the meltdown of the Chernobyl Nuclear Power Plant, boric acid was dumped in large quantities over Reactor 4 to hinder further fission reactions from taking place.
Thus, from production of modern hi tech glasses used in plasma screens, LCDs, etc., to increasing the efficiency of manufacturing processes, the uses of boric acid continue to show an upward trend.
However, it is vital to remember that boric acid does have a certain amount toxicity, and long-term exposure to it might be dangerous. Prolonged contact of boric acid with the skin and eyes may result in irritation, while ingesting it can even prove to be fatal. Hence, it is advisable to exercise caution while working with this compound.