Biodegradability amphoteric surfactants

Most surfactants used are anionic surfactants followed by nonionic ones. Cationic surfactants often pose environmental problems since they are not easily biodegradable. Amphoteric surfactants are expensive and therefore they are only used for special applications. 

Contrary to anionic and nonionic agents, they have poor detergency and are used more in the preparation of germicides, fabric softeners, and emulsifiers. Amphoteric surfactants are produced in much smaller amounts (5xl04 metric tons, near to 2% of the total production) [125] they are biodegradable and their ecotoxicological importance can be considered low. Their environmental occurrence up to know has been just occasional. 

To our best knowledge there are no studies on the anaerobic biodegradation of amphoteric surfactants hitherto published. 

As previously mentioned, amphoteric surfactants presently represent a minor fraction of the total surfactants production with only specialty uses. They are compounds with both anionic and cationic properties in aqueous solutions, depending on the pH of the system in which they work. The main types of these compounds are essentially analogs of linear alkane sulfonates, which provide numerous points for the initiation of biodegradation, and pyridinium compounds that... 

In addition, because they are generally based on aminoacid structures, they are among the most biodegradable surfactants available to the formulator. Products based on amphoteric surfactants are usually readily biodegradable, thus having a minimal impact on the environment. 

Table 22.21. Data obtained for the biodegradability of amphoteric surfactants...

The surfactants used in a shampoo will be selected on the basis of several criteria such as detergency, foam volume and texture, irritation, cost, compatibility with other ingredients, color, odor, purity, and biodegradability. Usually, primary surfactants used in shampoos are anionic and inexpensive. They may be combined with secondary surfactants, such as nonionic or amphoteric surfactants (Table 6.7). 

MAZOX Amine Oxides are nonionic surfactants at neutral or alkaline pH ranges. In acidic solutions, amine oxides are mildly cationic. They are also fully biodegradable and compatible with all types of surfactants, such as anionics, cationics, nonionics and amphoterics. 

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