Center of Excellence for Color Science and Technology,Department of Organic Colorants, Institute for Color Science and Technology
Dissolution of azo dyes derived from N-carboxylic acid-1,8-naphthalimide was studied in aqueous solutions containing formaldehyde condensation of naphthalenesulphonic acid and fatty alcohol ethylene oxide compound surfactants and effect of additional hydroxyl group on chemical structure of dye on dissolution was investigated. In addition, the effect of important factors on dissolution of used dyes in surfactant solutions such as the concentration of surfactants, temperature and time were considered. The results revealed that the dissolution rate of both dyes in formaldehyde condensation of naphthalenesulphonic acid was greater than the fatty alcohol ethylene oxide compound. In the same circumstance, the dissolution values of dyes indicated that dye 2 containing N-ethyl-n-2-hydroxyethyl aniline had more solubility than dye 1 containing N,N-diethylaniline that it can be attributed to the greater hydrophilicity of the dye 2 relative than dye 1. The results suggested that the dissolution of dyes in water containing surfactants was depended on the chemical structure of dyes and the type of used surfactants.