Adsorption of reactive dyes and surfactants onto chitin from mixtures containing surfactants at constant concentration and dyes at variable concentration was investigated in the present study. Two vinyl-sulfonate dyes (Scarlet R, Brillantorange 3R); chlorotriazine dye (Black DN); anionic (Borutosol KRN, Siarczanol N-2) and non-ionic (Rokafenol N-8) surfactants were tested. The experiments were carried out without and with pH adjustment.
The research have proved that at pH 6.2 and in surfactants presence the adsorption of vinyl-sulfonate dyes onto chitin was lower than without surfactants (control sample). It was observed that the maximum adsorption capacity of chitin in mixtures of Scarlet R and surfactants was about 3-fold lower than without surfactants and in mixtures of Brillantorange 3R and surfactants was from 2.5 to 4.1-fold lower than in control sample. At pH 3.0 the differences between maximum adsorption capacity of chitin for dyes from aqueous solutions and containing surfactants ranged from 2% (in mixture of Brillantorange 3R and Borutosol KRN) to 23% (in mixture of Scarlet R and Siarczanol N-2). The maximum adsorption capacity of chitin for Black DN (chlorotriazyne dye) in surfactants presence (from 140 to 290 mg/dm³) was higher at pH 6.2 as well as at pH 3.0 in comparison to control sample. Rokafenol N-8 was adsorbed the weakest onto chitin from among tested surfactants. At pH 3.0 for vinyl-sulfonate dyes the relationships between mass proportion of dye and surfactant adsorbed onto chitin (Q_dye/Q_SAA^*) and initial concentration proportion of dye and surfactant in solution (C_dye/C_SAA) was nearly linear. This indicates that dyes competed with surfactants of active sites of chitin.
SAA^* - Surface Active Agent (s)