Abstract
Sorption isotherms of purified disperse dyes on various polymers from water were carefully measured. Azo dyes (C. I. Disperse Orange 5, Red 1, 17, 19, etc.) and an anthraquinone dye (Disperse Red 15), and cellulose film, secondary cellulose acetate fiber, Nylon 6 film and fiber and poly (ethylene terephthalate) microfiber and film were used. Most of the sorption isotherms measured were not linear but curved convex to upward and were expressed satisfactorily in terms of dual-sorption model of the linear combination of Nernst-type partitioning and Langmuir sorption, The amounts of the dyes sorbed by Langmuir sorption were usually smaller than that by the partitioning.
In dyeing of cellulose, secondary cellulose acetate and Nylon 6, the contribution of the Langmuir sorption to the total dye sorption (CL/Cf) was large for the azo dyes with two N-substituted 2-hydroxyethyl group and Red 15, while for the azo dyes with one N-substituted 2-hydroxyethyl group, CL/Cf was small. CL/Cf decreased with increasing temperature, particularly for the azo dyes with one N-substituted 2-hydroxyethyl group. Consequently, the isotherms of these dyes at higher temperature seemed to be as if linear.
In dyeing of poly (ethylene terephthalate) fiber, CL/Cf was appreciably large even for the dye with one N-substituted 2-hydroxyethyl group such as Orange 5.
