Amphoteric surfactant refers to a surfactant that simultaneously contains the anionic and cationic hydrophilic group, and also contains hemaphroditic ions that are able to form cations or anions according to environmental conditions (such as pH changes). In other words, surface active compounds with both acidic and alkaline properties are known as amphoteric surfactants. Amphoteric surfactants include two main groups, betaine and real amphoteric surfactants.
As mentioned earlier, amphoteric surfactants contain two types, one of which is sensitive to pH and the other is not sensitive to all pH levels, and in practice, the cationic part is usually accepted from amine salt or the four groups of ammonium hydrophil. The anionic part is carboxylate, sulfonate, hydrophilic phosphate in particular, amino acid amino acids, which include both amino and carboxylic or intramolecular ammonium.
The amphoteric surfactant hydrophilic group has a negative and positive charge, so the net charge of the molecule is zero. The main characteristic of amphoteric surfactants is that their behavior depends on pH. For acidic solutions, the molecule acquires a positive charge and behaves like a cationic surfactant, while in alkaline solutions it becomes negative and behaves like an anion. At their individual isoelectric point, the properties of amphotericic surfactants are very similar to those of non-ionic surfactants.
Amphoteric surfactants are very suitable for use in formulations that contain a lot of electrolyte and are compatible with other types of surfactants, so in personal care products such as shampoos and conditioners, liquid soaps and cleansing lotions, etc. All-purpose and industrial cleaning materials are used. The total volume of amphoteric surfactants used in commercial products today is relatively small, but due to the demand for mild surfactants, the consumption of these chemicals is expected to increase significantly in the future.
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