Amphoteric surfactants classification

An unknown commercial detergent may contain some combination of anionic, nonionic, cationic, and possibly amphoteric surfactants, inorganic builders and fillers as weU as some minor additives. In general, the analytical scheme iacludes separation of nonsurfactant and inorganic components from the total mixture, classification of the surfactants, separation of iadividual surfactants, and quantitative determination (131). 

Some types of amphoteric surfactants (to be discussed below) in which the nitrogen is covalently bound to a group containing an anionic (e.g., -CH2CH2S03") or potentially anionic (e.g., -COOH) functionality are also classed as cationic in some publications however, under the classification scheme employed in this work, such materials are covered in a separate category. The examples above represent the simplest types of cationic surfactants. Many modem examples contain much more complex linkages however, the basic principles remain unchanged. 

The classification of surfactants in common usage depends on their electrolytic dissociation, which allows the determination of the nature of the hydrophilic polar group, for example, anionic, cationic, nonionic, and amphoteric. As reported by Greek [18], the total 1988 U.S. production of surfactants consisted of 62% anionic, 10% cationic, 27% nonionic, and 1% amphoteric. 

A simple classification of surfactants, based on the nature of the hydrophilic group, is commonly used, with four main classes being distinguished anionic cationic amphoteric and nonionic. A useful technical reference here is McCutcheon [3], which is produced annually to update the list of available surfactants. A recent text by van Os et al. [4], hsting the physico-chemical properties of selected anionic, cationic and nonionic surfactants, has been published by Elsevier. 

Properties Amphoteric Uses Surfactant in cosmetics Sodium caproamphopropionate Synonyms Decanamide, N-[2-[N-(2-hydroxyethyl)-N-(2-carboxyethyl) amino] ethyl]-, monosodium salt Classification Org. compd. 

Classification Substituted imidazoline Properties Amphoteric Uses Surfactant in cosmetics hydrotrope synergizes detergency with ethoxylated nonionics, improving wetting, penetrating, and detergency... 

There are fom basic classifications of textile surfactants cationic, anionic, nonionic, and amphoteric [10]. Overall, usage is about 59% anionic (25% natural soaps, 34% synthetic), 33% nonionic, 7% cationic, and 1% amphoteric [36]. Alkylphenol ethoxylate (APE) surfactants are one of the largest groups of nonionic surfactants, accounting for over 400 million pounds per year in the United States [37]. These fom categories include major product types shown in Table 7.16 [10, 31, 37, 38],... 

A simple classification of surfactants based on the nature of the hydrophilic group is commonly used. Three main classes may be distinguished, namely, anionic, cationic, and amphoteric (3-5). It should be mentioned also that a fourth class of surfactants, usually referred to as polymeric surfactants, has been used for many years for preparation of emulsions and suspensions and their stabilization. 

Although betaines are commonly classified among amphoterics, we preferred to cover this class of surfactants in a previous topic devoted to quaternaries (Sec. H.B.3.C.). Indeed, as already explained, the classification of betaines as amphoterics is improper because these surfactants never exhibit in single anionic form. 

A detailed classification of the chemical compounds usually employed was given by (Dubief et al., 2005). The most important of these are organic acids (carboxylic acids and aromatic sulphonic acids), fatty compounds and their derivatives (fatty acids, fatty alcohols, natural triglycerides, natural waxes, fatty esters, oxyethylenated and oxypropy-lenated waxes, partially sulphated fatty alcohols, lanolin and its derivatives, ceramides), vitamins (A, B and E) (see Section 8.6), protein derivatives (extracts or hydrolysates of keratin, collagen and vegetable proteins), silicones (dimethicone and others), cationic surfactants, cationic polymers, amphoteric and betainic polymers. 

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