Hydrogen peroxide

Hydrogen peroxide (H₂O₂) is a very pale blue liquid which appears colorless in a dilute solution, slightly more viscous than water. It is a weak acid. It has strong oxidizing properties and is therefore a powerful bleaching agent that is mostly used for bleaching paper, but has also found use as a disinfectant, as an oxidizer, and in rocketry (particularly in high concentrations as high-test peroxide (HTP) as a monopropellant, and in bipropellant systems. The oxidizing capacity of hydrogen peroxide is so strong that the chemical is considered a highly reactive reactive oxygen species.

History

Hydrogen peroxide was first isolated in 1818 by Louis Jacques Thénard by reacting barium peroxide with nitric acid. An improved version of this process used hydrochloric acid, followed by sulfuric acid to precipitate the barium sulfate byproduct. Thénard’s process was used from the end of the 19th century until the middle of the 20th century. Modern production methods are discussed below.

Uses

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 an environmentally benign alternative to chlorine-based bleaches.

Other major industrial applications for hydrogen peroxide include the manufacture of sodium percarbonate and sodium perborate, used as mild bleaches in laundry detergents. It is used in the production of certain organic peroxides such as dibenzoyl peroxide, used in polymerisations 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 peroxy acid. Peracetic acid and meta-chloroperoxybenzoic acid (commonly abbreviated mCPBA) are prepared from acetic acid and meta-chlorobenzoic acid, respectively. The latter is commonly reacted with alkenes to give the corresponding epoxide. In PCB manufacturing process, hydrogen peroxide mixed with sulfuric acid was used as the microetch chemical for copper surface roughening preparation.

New industrial and home applications may be developed with the discovery of a catalytic reaction using powdered precious metal-based catalyst, hydrogen peroxide and methyl alcohol. A small plastic bottle incorporating these can produce superheated steam in one to two seconds releasing only CO₂ and high temperature steam for a variety of purposes.

Some gardeners and users of hydroponics advocate the use of hydrogen peroxide in watering solutions. They claim that its spontaneous decomposition releases oxygen that enhances a plant’s root development and helps to treat root rot (cellular root death due to lack of oxygen).