SORPTION KINETICS OF AZO DYES ONTO CHITOSAN - BASED COMPOSITES

Novel cationic composite hydrogels based on chitosan (CS) and poly (N-2aminoethyl acrylamide)(PAEA) covalently cross-linked with glutaraldehyde (GA) were synthesized and tested as sorbents for two dis-azo dyes like: Congo Red (CR) and Direct Blue1(DB1) from aqueous solutions. Three CS-based composite hydrogels having different molar ratios between the primary amine groups and the cross-linking agent (GA/NH 2 = 5.3 and 12.5), the same total concentration of polycations (C PC = 2 wt%) and various molar ratios between polycations (PAEA:CS = 0.25 and 1.2) were used for this study. The effect of temperature on the adsorption of dyes (CR, DB1) onto CS-based composite hydrogels has been investigated. The pseudo-second order model described well the kinetic of adsorption. The adsorption of CR and DB1 on the composite hydrogel was around, 96% for CR and 97% for DB1.