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Hydrogen Peroxide in Textile Production

Hydrogen Peroxide in Textile Production.

When hydrogen peroxide interacts with organic materials, it undergoes an oxidation reaction with them. Visually, this appears as lightening (bleaching) of the material’s surface. For this reason, peroxide has long been used for a considerable time to bleach materials such as wool, leather, silk, and other materials, including hair (in cosmetology).

Bleaching Wool with Hydrogen Peroxide Solution

In standard bleaching, wool products are washed and cleaned, after which they are impregnated with a special bleaching solution containing 1.3% hydrogen peroxide; to raise the pH to 9, tetrasodium pyrophosphate with ammonia or sodium silicate is also introduced. After such treatment, the material becomes softer to the touch.
After wringing, the material is left for at least a day, after which it is rinsed.
To speed up the process, bleaching can be carried out at an elevated temperature (up to 49°C). This technological approach reduces process time to 1-12 hours and reduces peroxide consumption to 0.4-0.8% (by mass).
On an industrial scale, for wool products, the “internal drying” technology is used — washed wool is placed directly into a hydrogen peroxide bleaching solution with 0.3-0.9% (by mass) content at a solution pH of 3-5.

However, raising the temperature leads to excessive darkening of wool materials when residual peroxide is not fully decomposed. Rinsing alone does not solve this problem. Residual peroxide is removed by an additional treatment process using sodium hydrosulfite.
This operation can sometimes be skipped if the process is set up correctly and residual peroxide decomposes on its own within a short time.

In laundries, the method described above is used to bleach not only materials of animal origin, but also cellulosic materials, using an alkaline solution of sodium peroxyborate and peroxide.

Wool bleached using hydrogen peroxide

The Effect of Hydrogen Peroxide on Wool Properties

In a number of industries, such as felt production, a characteristic of wool material called “felting ability” plays an important role. This is the ability of heated, moist fibers to bond together. Different types of wool, as well as other materials of animal origin, can show strong deviations from the required bonding capability.
For hats (felt production), the required capability is obtained by oxidizing the material. This is a very carefully controlled process.
In the past, Nitric acid was used, with mercury salts as a catalyst. Then, in 1936, this poisonous solution was replaced with a safe one — a solution of mineral acid in hydrogen peroxide.
Treating wool with peroxide is also used together with chlorination, which makes the material resistant to shrinkage. This is achieved because alkaline hydrogen peroxide solutions have the ability to reduce “felting ability.”

Hydrogen Peroxide for Hair Bleaching

For bleaching hair, such as fur, horsehair, and also human hair (in cosmetology), peroxide is used.
If there is a risk of over-oxidation, as well as high pH or elevated temperature, a mixture of peroxide with ammonium peroxydisulfate is used. This method is applied, for example, when processing cashmere.

Hydrogen peroxide is also used to bleach bone, feathers, and mother-of-pearl, as well as for bleaching so-called vegetable “ivory” (Phytelephas), which is the shell of palm fruits.
Sausage casings, tobacco, cork, sponge, eggs, and glue are also bleached this way.

Fats, soaps, oils, juices, and waxes are also decolorized by the action of hydrogen peroxide. For oils and fats, great attention is paid to the concentration of the peroxide solution used.
A specific process scheme has been developed for each type of product.

A more detailed description of the properties of Hydrogen peroxide is here.

As well as a brief description of wood bleaching, for concrete production, and for pool cleaning.

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