Hydrogen peroxide is corrosive and a
strong oxidizer, and has a formula of H2O2. It is a clear
viscous liquid and has a slightly sharp smell. It can be found in organisms and
as a by-product of oxidative metabolism. Due to differences in effects of
hydrogen bonding, aqueous solution of hydrogen peroxide and pure solutions
differs in freezing point temperature. In aqueous solution, water and hydrogen
peroxide forms a eutectic mixture and exhibits a freezing point depression.
Hydrogen peroxide is mainly
used as a bleaching agent in textile industry, in the pulp and paper industry
during chemical and mechanical pulping process and in cosmetics industry. They
are more environmental friendly than the chlorine-based bleaches and can be
used to manufacture a wide range of organic and inorganic compounds.
The manufacturing process of hydrogen
peroxide includes 4 main steps:-
1. Hydrogenation of an anthroquinone: - A solution of the
2-ethylanthraquinone in a mixed solvent system containing a non-polar
hydrocarbon and a polar solvent, and a suspension of a nickel or
palladium-based catalyst on a solid support, is hydrogenated using hydrogen gas
at 320 K. Reduction to the 2- alkylanthraquinol occurs. The catalyst
is removed by filtration and recycled.
2. Oxidation of the anthraquinol:-The solution of 2-ethylanthraquinol is then oxidized by air to a
hydroperoxide, which reacts in water to reform 2-ethylanthraquinone and produce
a dilute solution of hydrogen peroxide. Thus the overall reaction is:
H2 + O2 àH2O2
3. Extraction of hydrogen peroxide
solution:-Water is added to extract the peroxide as an
aqueous solution containing 40% hydrogen peroxide. The organic solvent
layer is recycled to the hydrogenation unit for further reaction.
4. Purification and concentration of
hydrogen peroxide:-The aqueous hydrogen peroxide
solution is treated with organic solvents and by air being pumped through to
remove residual quinone and solvents and produce the standard 40% product.
Hydrogen peroxide in its purest form
is inherently stable. However, if brought into contact with certain
contaminants (mainly heavy metals) it can decompose. Therefore, stabilisers are
normally added to the product. They act by complexing with any traces of
transition metal ions present which would otherwise catalyse the decomposition
of hydrogen peroxide.
Hydrogen peroxide is mainly used as a
bleaching agent in the pulp and paper industry during chemical and mechanical
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
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
hyroquinone, ketones, aldehydes, alcohols, hydro-oxyl amines, epoxy
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 a mild bleaches
for the laundry.