Hydrogen peroxide was prepared first by Thenard in 1818. It is a colourless liquid at room temperature with a bitter taste. Small amounts of gaseous hydrogen peroxide occur naturally in the air. Hydrogen peroxide is unstable, decomposing readily to oxygen and water with release of heat. Although non-flammable, it is a powerful oxidizing agent that can cause spontaneous combustion when it comes in contact with organic material.
There are two main methods to produce H2O2. They are:
Method 1: Auto-oxidation of ethyl anthraquinol in a solvent such as toluene or ethylbenzene. The product ethyl anthraquinone is reduced by hydrogen over supported nickel or platinum catalyst to regenerate back the starting material, ethyl anthraquinol for a continuous production of H2O2.
Method 2: Electrolytic conversion of aqueous sulfuric acid to peroxydisulfate followed by hydrolysis to H2O2. This is also known as the Weissenstein process.
Hydrogen peroxide is mainly used as a bleaching agent in the pulp and paper industry during chemical and mechanical pulping process.
Hydrogen peroxide is used as a bleaching agent in textile industry and they are more environmental friendly than the chlorine-based bleaches. Hydrogen peroxide is also used in dyes. Sulphur dyes work with an oxidation-reduction dyeing method and hydrogen peroxide is used as an oxidizing agent. Once the dyes are adsorbed onto the cellulosic, oxidation will settle the dyes permanently and changing it into a water-insoluble form.
Waste Water Treatment
Hydrogen peroxide is a cleaner oxidizing agent which is used to treat waste water, contaminated soil, and toxic air emissions.
Hydrogen peroxide is also used to manufacture a wide range of organic and inorganic compounds such as hydroquinone, ketones, aldehydes, alcohols, hydro-oxyl amines, epoxy derivatives, etc.
Hydrogen peroxide is used in pharmaceuticals for preparing disinfectants, food processing for sanitizing of packages, etc. They are even used as propellants and in explosives. In addition, Hydrogen peroxide is mainly used in the manufacturing of sodium percarbonate and other chemicals which are generally used as mild bleaches for the laundry.