Bleachable stains

Laundry powders in Europe use sodium percarbonate and a bleach activator, tetraacetylethylenediamine ( ED), to form peracetic acid in the washing machine that then reacts with bleachable stains such as tea, red wine, coffee, and curry to remove /bleach them from cloth. Transition metal ions, in particular copper, cause first decomposition of peracetic add before it can bleach stains and second react with peroxide to form highly readive hydroxyl radicals that can cause dye and fabric damage [32]. Chelants bind with copper and other metals to prevent these unwanted side readions. 

A certain part of some stains will also be removed by water or the detersive parts of the formulation and the degree of bleachable stain removal achieved is, to a first approximation, the sum of the contribution from the bleach system and that from the other components. The relative contributions depend on the nature and history of the stain. Test stains, whether produced in-house or purchased from a commercial supplier, that have not been aged realistically tend to be more easily removed via the action of components other than the bleaching system. 

There is a minimum level of peroxide and TAED in the wash bath below which no benefit on bleachable stains is seen. This threshold effect is believed to be due to the presence of noncolored oxidizables in the wash bath that are more readily oxidized than the stain molecules. 

It should be noted that biocidal activity is present even when the bleach-actives levels are too low for effective removal of bleachable stains. 

HOO oxidizes bleachable soils and stains. The most used source of hydrogen peroxide is sodium perborate, known as sodium peroxoborate tetrahydrate, NaB03-4H20, that in crystalline form contains the per-oxodiborate anion [4, 17]. 

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