Dynamic adsorption of gemini and conventional cationic surfactants onto polyacrylonitrile

The role of dodecyltrimethylammonium bromide (DTAB) and a series of gemini cationic surfactants in the adsorption rate of methylene blue (MB) on acrylic fibres has been studied by means of TOC, UV–vis and FT-NMR spectroscopy. The influence of surfactant concentration, alkyl chain and spacer length of geminis has been investigated at different temperatures. The dye adsorption rate increases with increasing temperature, while the retarding action of gemini cationic surfactants is much stronger than that of the corresponding monomeric surfactants. There are small differences among the geminis with the same alkyl chain but with various spacer lengths.