Adsorption Mechanism of a Cationic Surfactant on Textiles in Excess Anionic Surfactant Solution

Many studies have been carried out on the mechanism of the adsorption of anionic and cationic surfactants on textiles. The case of cationic and anionic surfactants used in combination has also been reported. In such a case, the cationic surfactant is treated as a dispersion and when used with excess anionic surfactant solution, it is not adsorbed on textiles. In the present research, it was found that if a cationic surfactant is used as a corpuscle (fine solid, over 10 μm) in the presence of excess anionics, adsorption on to various textiles becomes possible. For an understanding of this phenomenon, the work of adhesion (Wa) between an anionic/cationic surfactant complex and the surface of a textile was calculated, measuring the contact angle of 2 liquids with the complex by Wu's equation. Wa and the amount of adsorbed cationic surfactant on textiles were found to show a very close correlation. Thus, in an excess anionic surfactant solution, an anionic/cationic surfactant complex is apparently formed on the surface of a corpuscle of a cationic surfactant, and the work of adhession between this complex and each textile is related to the adsorption (or deposition) of a cationic surfactant on textiles.