Detergent builders soften water by holding free water ions, such as magnesium and calcium. This prevents these particles to react with other ingredients of detergent, which would have caused them to work less efficiently or precipitate from solution (soap scum). They can produce insoluble salts, which become beset in the clothes and deposit on solid surfaces inside the washing machine. In this manner, builders also help in extending the life of the washing machine. Soil molecules are sometimes bound to the clothes surface by calcium ion bridging, removal of hardness from the environment and therefore help in removal of stains. Sometimes more than one detergent builder is used in a product, to develop a builder system with more effective cleaning performance.
On the basis of characteristics and properties, detergent builders can be categorized into two types
- Organic detergent builders
- Inorganic detergent builders
Traditionally, sodium tripolyphosphate (STPP) was the builder of choice. It offers superior water softening because of its high binding capacity for heavy metals and calcium ions, good buffering properties that contribute to detergency action and superior anti-redeposition properties. In addition, the position of STPP as a preferred builder during 1940s-1970s was further boosted because of its low toxicity. Although STPP has low toxicity, as a nutrient, it has the potential result in eutrophication (a term used to describe water that is 'over rich' in nutrients, and may to an excessive growth of algae). This led to the search for alternative products and the development of synthetic detergent Zeolite, which now days, is the principle alternative to phosphate builders.
Builders are basically water softeners that are used to soften wash water by extracting and binding the magnesium and calcium ions. Due to the action of builder, the availability of these ions is removed from the wash-water solution, and as result the hardness of wash-water is removed. Depending on the type of builder, other benefits may be available, such as -
- Buffering of wash water in the alkaline range
- Help prevent the redeposition of soils after they have been removed from the fabric by surfactants
- Carry absorbed liquid components in the products, like surfactants so as to produce a dry and free flowing powder
- Typically improve the wetting and emulsification characteristics of detergent
The prime function of detergent builders is to upgrade and prevent the cleaning efficiency of surfactants. Builders offer a number of advantages, including softening, buffering, and emulsifying. Some of the important advantages of using a builder in a wash solution are -
- Soften water by deactivating the hardness minerals (metal ions such
as calcium and magnesium. The softening process is followed by two
processes - one is sequestration (holding metal ions in solution) and
another is precipitation (removing metal ions from solution as insoluble
- In addition to softening, builders also provide a desirable level of
alkalinity (increase pH) that improves cleaning performance. They also
work as buffer to maintain suitable alkalinity in wash water.
- Help emulsify oily and greasy soil by breaking it up into small parts. Different builders in reality peptize or suspend loosened dirt and keep them from settling back on the cleaned surface.