Hydrogen peroxide bleaching

In traditional peroxide bleaching, hydrogen peroxide is activated by alkali. Acids, both inorganic and organic, can also be used to activate peroxide by the formation of a peracid. Peracids can be effective oxidative bleaching agents and, at least potentially, offer an alternative to the environmentally sensitive chlorine bleaches. Although known for quite... 

Separate peroxygen bleaches, hydrogen peroxide, or its sources like sodium perborate or sodium percarbonate from water to prevent premature reaction, such as by suspending the solids between surfactant lamellae in the structured liquid. 

In oxidation reactions, however, osmium is significantly more selective than catalysts derived from other transition metals. Osmium-based catalysts for the hydroxylation and amination of aUcenes are very widely used in organic synthesis. With alkaloid-derived ligands, the hydroxylation and amination reactions are highly enantioselective (see Enantioselectivity). The use of bleach, hydrogen peroxide, ferric cyanide, and oxygen have been reported as secondary oxidants for some of these reactions. 

Peroxygen (active oxygen) bleaches hydrogen peroxide, peroxy, and peroxyhydrate compounds, peracids, and related. 

As an alternative bleach, hydrogen peroxide may be used, but is less cost-efficient and can cause process control difficulties due to excess foaming because of liberation of oxygen during bleaching. 

Hydrogen peroxide in aqueous solution has many uses, because the products from its reaction are either water or oxygen, which are generally innocuous. The chief use is bleaching of textiles, both natural and synthetic, and of wood pulp for paper. Other uses are the oxidation of dyestuffs, in photography and in the production of... 

The most common chemical bleaching procedures are hypochlorite bleach for cotton hydrogen peroxide bleach for wool and cotton sodium chlorite bleach for cotton, polyamide, polyester, and polyacrylonitrile and reductive bleaching with dithionite for wool and polyamide. 

An ammoniacal solution is added just before use to activate the hydrogen peroxide. Ammonia is preferred over sodium carbonate (40) or ethanolamines for maximum bleaching. The alkaline solution can be formulated iato a shampoo vehicle with oleate soaps or ethoxylated fatty alcohols. When the bleach is appHed to areas such as new hair growth, a viscous cream or paste may be preferred, formulated with fatty alcohols, alkanolamides, or other thickeners. 

Bleaches of the simple ammoniacal peroxide type give limited lightening, which can be increased with bleach accelerators or boosters, including one or more per salts such as ammonium, potassium, or sodium persulfate or their combinations. These salts, which are susceptible to decomposition in aqueous solution, are packaged as dry powders and added just before use. In the absence of hydrogen peroxide, however, persulfates do not have any bleaching effect (41). 

The amount of oxygen evolved is not related to the degree of bleaching (40). Oxidative decoloring is caused by hydrogen peroxide or by the HO ions present in alkaline solution. Hydrogen peroxide is also an effective solvent for melanin (41). 

Neutralizing Lotion. The principal active ingredient of cold wave neutralizers is usually an oxidizing agent. The most popular is hydrogen peroxide [7722-84-1J, employed at a concentration of 1—2% it continues to find widespread use. Aqueous solutions of sodium bromate [7789-38-0] at a concentration of 10—20% occasionally are used and are technically preferred over the peroxide formulations because of excellent stabiUty and absence of hair bleaching. Neutralizing powders appear to be on the decline but formulations stiU in use consist of sodium perborate [7632-04-4] combined with hexametaphosphates to improve solubiUty in hard water. 

Bleaching. The largest single use for hydrogen peroxide in the United States and North America is wood pulp bleaching, but consumption for the manufacture of chemicals, environmental appHcations, and for bleaching cotton (qv), wool (qv), and other textiles (qv) is significant. 

Hydrogen peroxide is also used to bleach soHd surfaces such as wood (qv) or linoleum, and to improve the color of oils and waxes. 

Sodium peroxoborate hexahydrate is an important ingredient of many household detergents, working best at temperatures above 60°C. It is also used in dishwasher detergents, denture cleaners, as well as foot and bath salts. The textile industry generally uses hydrogen peroxide for bleaching, but there are a few areas in which sodium peroxoborate hexahydrate is preferred. 

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