How is bleach used for laundry



Bleach (“Bleaching”) are substances that weaken the color of raw materials in the paper and textile industry or when washing textiles. During the bleaching process, substances that are contained in the fibers and discolor them are chemically destroyed. Usually this happens through oxidation of these substances; corresponding bleaches are oxidizing agents. Previously used procedures based on chlorine are increasingly being carried out in consideration of the environment by (more complex) Oxygen-based Procedure replaced.

application

In the paper industry, pulp is bleached with chlorine dioxide or hypochlorite. The ecologically questionable bleaching with elemental chlorine is disappearing. Environmentally friendly, completely chlorine-free processes with hydrogen peroxide or ozone are more cost-intensive and are mainly used in the Scandinavian countries. Pulp bleached with chlorine dioxide is also called ECF (elementary chlorine free) pulp; bleached with hydrogen peroxide / ozone than TCF (totally chlorine free) pulp.

With the help of bleaching agents, unwanted color stains and yellowing can be removed from the laundry. Bleach has a disinfectant effect, but it can also damage the laundry. In heavy-duty detergents, bleach only becomes effective at higher temperatures. In contrast, mild detergents and colored detergents contain no bleaching agents. Oxygen-based bleach is almost always used for textile cleaning in the home, especially hydrogen peroxide in liquid and sodium perborate in powdered bleach. Chlorine-based bleach is still used in industrial textile cleaning and textile processing.

Chemical basics

The release aggressive, atomic oxygen is (in general, see below) the basis of the bleaching process. The oxygen combines with unwanted dyes and sensitive textile dyes. bleaching agents based on oxygen can be found in modern detergents and in stain remover. bleaching agents based on oxygen means that this bleach releases oxygen from hydrogen peroxide (or ozone). Such bleaching agents are adjusted to the special bleaching conditions by means of various magnesium-containing stabilizers for commercial products. - used to be Chlorine based bleach(Sodium hypochlorite) is used. You put, differently bleaching agents based on oxygen, Oxygen radicals directly free. However, they pollute the environment and are therefore hardly used any more.

A widespread bleach in heavy duty detergents is or was Perborate. It was pushed back by other means, because its boron compounds are difficult to break down and, in high concentrations in the water, are harmful to plants. In stain tabs, stain removers and modular detergents Percarbonate used. Due to its complicated composition, it can Percarbonate difficult to integrate into heavy-duty detergents. Since perborate and percarbonate only become active from a temperature of 60 degrees, so-called bleach activators are used as additives.

In dry cleaning, peracetic acid (CH3CO3H) because it degrades quickly in wastewater and is therefore environmentally friendly.

What all bleaching agents have in common is their attack on conjugated PI electron systems, which are mostly colored. When most natural fibers are bleached, the fiber is also damaged. The degree of polymerization decreases.

The bleach can too reductive done with sodium dithionite. Garments dyed with indigo, such as blue jeans, can be efficiently bleached with it.

History of bleach

About 7000 years ago sulfur was used as a bleaching agent for textiles. Eau de Javel (Javelwasser) is considered to be the first chemical bleaching agent. Its effectiveness was first demonstrated in 1785 by Claude-Louis Berthollet. Before 1900, the damp laundry was de-yellowed with a lawn bleacher. The chemical processes used in this process are also used today in modern laundry detergents and bleaches. The solar radiation produced hydrogen peroxide, which then released oxygen radicals, which then destroyed the pigment. From the 20th century, modern detergents and bleaches were developed.

Categories: Cleaning Agents | Chemical group