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Bleaching Mechanism of Hydrogen Peroxide
Bleaching mechanism of hydrogen peroxide
Hydrogen peroxide is chemically active and has a wide range of applications in many fields, and its bleaching effect is particularly significant. The following is a detailed explanation of its bleaching mechanism.
Hydrogen peroxide partially ionizes in aqueous solution, generating hydrogen ions ($H ^ + $) and hydrogen peroxide radical ions ($HOO ^ - $), which lays the foundation for subsequent bleaching reactions.
From the perspective of free radicals, under specific conditions, hydrogen peroxide can produce hydroxyl radicals ($\ cdot OH $). For example, in the presence of metal ions (such as iron ions $Fe ^ {3 + }$ 、 manganese ions $Mn ^ {2 +} $, etc.) or under the influence of light and other conditions, hydrogen peroxide will decompose and produce highly active hydroxyl radicals. Hydroxyl radicals have strong oxidizing ability and can attack unsaturated bonds in organic pigment molecules, such as carbon-carbon double bonds ($C = C $), carbon-oxygen double bonds ($C = O $), etc. These unsaturated bonds are the key structures for the color of organic pigments. Hydroxyl radicals oxidize and destroy them, changing the molecular structure, thereby making the pigment color lighter or disappear, achieving bleaching effect.
According to the action of hydrogen peroxide ions, hydrogen peroxide ions ($HOO ^ - $) are also oxidizing. It can react with some substances containing oxidizable groups, such as some organic compounds with reducing properties. During the reaction with these substances, hydrogen peroxide ions accept electrons, are reduced themselves, and at the same time oxidize organic compounds to change their structures, thereby achieving the purpose of bleaching.
In addition, the pH of hydrogen peroxide bleaching systems also has an important impact on their bleaching mechanism. Under alkaline conditions, the balance of hydrogen peroxide ions produced by hydrogen peroxide decomposition shifts to the right, and the concentration of hydrogen peroxide ions increases, enhancing the bleaching effect. At this time, hydrogen peroxide ions not only directly participate in the oxidation reaction, but also promote some impurities on the fiber surface to undergo reactions such as saponification, which further enhances the bleaching effect. Under acidic conditions, hydrogen peroxide is relatively stable, the decomposition rate of free radicals is slow, and the bleaching effect is relatively weak.
In summary, the bleaching mechanism of hydrogen peroxide is mainly realized through the oxidation of hydroxyl radicals and hydrogen peroxide ions generated, as well as the influence of the pH of the system on the reaction, so as to play an important bleaching function in the textile, papermaking and other industries.
Hydrogen peroxide is chemically active and has a wide range of applications in many fields, and its bleaching effect is particularly significant. The following is a detailed explanation of its bleaching mechanism.
Hydrogen peroxide partially ionizes in aqueous solution, generating hydrogen ions ($H ^ + $) and hydrogen peroxide radical ions ($HOO ^ - $), which lays the foundation for subsequent bleaching reactions.
From the perspective of free radicals, under specific conditions, hydrogen peroxide can produce hydroxyl radicals ($\ cdot OH $). For example, in the presence of metal ions (such as iron ions $Fe ^ {3 + }$ 、 manganese ions $Mn ^ {2 +} $, etc.) or under the influence of light and other conditions, hydrogen peroxide will decompose and produce highly active hydroxyl radicals. Hydroxyl radicals have strong oxidizing ability and can attack unsaturated bonds in organic pigment molecules, such as carbon-carbon double bonds ($C = C $), carbon-oxygen double bonds ($C = O $), etc. These unsaturated bonds are the key structures for the color of organic pigments. Hydroxyl radicals oxidize and destroy them, changing the molecular structure, thereby making the pigment color lighter or disappear, achieving bleaching effect.
According to the action of hydrogen peroxide ions, hydrogen peroxide ions ($HOO ^ - $) are also oxidizing. It can react with some substances containing oxidizable groups, such as some organic compounds with reducing properties. During the reaction with these substances, hydrogen peroxide ions accept electrons, are reduced themselves, and at the same time oxidize organic compounds to change their structures, thereby achieving the purpose of bleaching.
In addition, the pH of hydrogen peroxide bleaching systems also has an important impact on their bleaching mechanism. Under alkaline conditions, the balance of hydrogen peroxide ions produced by hydrogen peroxide decomposition shifts to the right, and the concentration of hydrogen peroxide ions increases, enhancing the bleaching effect. At this time, hydrogen peroxide ions not only directly participate in the oxidation reaction, but also promote some impurities on the fiber surface to undergo reactions such as saponification, which further enhances the bleaching effect. Under acidic conditions, hydrogen peroxide is relatively stable, the decomposition rate of free radicals is slow, and the bleaching effect is relatively weak.
In summary, the bleaching mechanism of hydrogen peroxide is mainly realized through the oxidation of hydroxyl radicals and hydrogen peroxide ions generated, as well as the influence of the pH of the system on the reaction, so as to play an important bleaching function in the textile, papermaking and other industries.
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