Effects of a bolaform electrolyte on the sorption of acid dyes by a nylon 6 film

The sorption behavior of acid dyes by a nylon 6 film was investigated in the presence and absence of a bolaform electrolyte. The time dependence of the sorption changed with the pH values of the dye bath. At pH 3, equilibrium sorption was not established even after the immersion of the film in the aqueous dye solutions for 7 days, while at pH 4 and in pure water, equilibrium sorption was established after the immersion for 1 day. The sorption isotherms were determined and analyzed by means of the bimodal sorption equation. The sorption parameters thus determined were greatly affected by the dye structure and the pH values. The addition of the bolaform electrolyte reduced the amounts of dye sorbed by the nylon 6 film. This is believed to be due to the formation of the complexes between the dyes and the bolaform electrolyte in the dye bath. Thus, the bolaform electrolyte retards the sorption through the formation of the complexes. (C) 1998 John Wiley & Sor..s, Inc.