Hydrogen peroxide

Uses

Domestic uses

It is commonly used (in very low concentrations, typically around 5%) to bleach human hair, hence the phrases peroxide blonde and bottle blonde. It burns the skin upon contact in sufficient concentration. In lower concentrations (3%), it is used medically for cleaning wounds and removing dead tissue. The Food and Drug Administration has approved 3% hydrogen peroxide ("Food Grade", or without added chemical stabilisers) for use as a mouthwash. Commercial peroxide solutions (most H2O2 bought over the counter from pharmacies) are not suitable for ingestion as they contain additional harmful chemicals.

Related Topics:
Hair - Food and Drug Administration

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Some gardeners and hydroponics implementers have professed the value of hydrogen peroxide in their watering solutions. They claim its spontaneous decomposition releases oxygen to the plant that can enhance root development and also help treat root rot, which is cellular root death due to lack of oxygen.

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Commercial peroxide, as bought at the drugstore in a 3% solution, can be used to remove bloodstains from carpets and clothing. If a few tablespoons of peroxide are poured onto the stain, they will bubble up in the area of the blood. After a few minutes the excess liquid can be wiped up with a cloth or paper towel and the stain will be gone.

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Storage

Household hydrogen peroxide solutions is commonly found in concentrations of 3% solution. As hydrogen peroxide decomposes in the presence of light, it should be stored in a cool environment out of direct sunlight. It should also be stored out of reach of children in a well marked bottle as ingestion of large amounts can cause gastrointestinal problems including burns, pain and vomiting.

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Stronger solutions such as a 35% solution have been responsible for at least one death when ingested undiluted.

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Industrial applications

About 50% of the world's production of hydrogen peroxide in 1994 was used for pulp and paper bleaching. Other bleaching applications are becoming more important as hydrogen peroxide is seen as a more environmentally benign alternative to chlorine based bleaches.

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Other major industrial applications for hydrogen peroxide include the manufacture of sodium percarbonate and sodium perborate, used as mild bleaches in laundry detergents. In addition it is used in the production of certain organic peroxides such as dibenzoyl peroxide, used as free radical initiators in polymerisation and other chemical processes. Hydrogen peroxide is also used in the production of epoxides such as propylene oxide. Reaction with carboxylic acids produces a corresponding "per-acid"; for industrial use peracetic acid is prepared in this way from acetic acid. MCPBA, used extensively in the laboratory, is likewise prepared from meta-chlorobenzoic acid.

Related Topics:
Sodium percarbonate - Sodium perborate - Laundry - Detergent - Organic peroxide - Dibenzoyl peroxide - Free radical - Initiator - Polymerisation - Epoxide - Propylene oxide - Carboxylic acid - Peracetic acid - Acetic acid - MCPBA

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Use as propellant

The use of H2O2 as a propellant takes advantage of the decomposition of hydrogen peroxide into water and oxygen. The propellant is pumped into a reaction chamber where usually a metal (esp. silver or platinum) catalyst triggers decomposition, the oxygen-water steam that is produced is either used directly or mixed with a fuel to burn. As a monopropellant (not mixed with fuel) it produces a maximum specific impulse (Isp) of 161 s (1.6 kN?s/kg) which makes it a low performance monopropellant. The famous Bell rocket belt used hydrogen peroxide monopropellant. When decomposed to burn a fuel as an oxidizer, specific impulses as high as 350 s (3.5 kN?s/kg) can be achieved, depending on the fuel. Peroxide was used very successfully as an oxidizer for the low-cost British launchers, Black Knight (rocket) and Black Arrow.

Related Topics:
Monopropellant - Specific impulse - KN - Rocket belt - Black Knight (rocket) - Black Arrow

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Compared to hydrazine, peroxide is much less toxic but it is also much less powerful. Peroxide gives a slightly lower Isp than liquid oxygen, but is dense, storable, non cryogenic and can be used to drive gas turbines to give high pressures. It also can be used for regenerative cool rocket engines.

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In the 1940's and 50's the Walter turbine used hydrogen peroxide for use in submarines while submerged; it was found to be too noisy and maintenance demanding compared to the conventional diesel-electric power system. Some torpedoes used hydrogen peroxide as oxidizer or propellant, but this use has been discontinued by most navies for safety reasons. Hydrogen peroxide leaks were blamed for the sinkings of HMS Sidon and the Russian submarine Kursk. It was discovered, for example, by the Japanese Navy in torpedo trials, that the concentration of H2O2 in right-angle bends in HTP pipework can often lead to explosions in submarines and torpedoes.

Related Topics:
Walter - Turbine - Submarine - Diesel-electric - Torpedo - Navies - HMS ''Sidon'' - Russian submarine Kursk

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While its application as a monopropellant for large engines has waned, small thrusters for attitude control which run on hydrogen peroxide are still in use on some satellites and provide benefits on the spacecraft, making it easier to throttle and safer loading and handling of fuel before launch (as compared to hydrazine monopropellant). However hydrazine is a more popular monopropellent in spacecraft because of its higher specific impulse and lower rate of decomposition.

Related Topics:
Attitude control - Specific impulse

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Therapeutic use

Hydrogen peroxide has been used as an antiseptic and anti-bacterial agent for many years. While its use has decreased in recent years due to the popularity of better smelling and more readily available OTC products, it is still used by many hospitals, doctors and dentists in sterilising, cleaning and treating everything from floors to root canal procedures.

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35 percent food-grade hydrogen peroxide has been marketed under names such as "Oxywater" or "H2O2", with claims of medicinal or therapeutic value as Hydrogen Peroxide therapy. Advocates of the product claim that it can be diluted and used for "hyper-oxygenation therapy" to treat AIDS, cancer, and many other conditions; some also claimed that information about these beneficial uses of peroxide have been suppressed by the scientific community.

Related Topics:
Hydrogen Peroxide therapy - AIDS - Cancer

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Recently, alternative medical practitioners have advocated administering doses of hydrogen peroxide intravenously in extremely low (less than one percent) concentrations for hydrogen peroxide therapy - a controversial alternative medical treatment for cancer. However according to the American Cancer Society, "there is no scientific evidence that hydrogen peroxide is a safe, effective or useful cancer treatment". They advise cancer patients to "remain in the care of qualified doctors who use proven methods of treatment and approved clinical trials of promising new treatments." {{an|cancer}}

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