Adsorption of some anionic azo dyes onto crosslinked poly(N-vinylpyrrolidone) from aqueous solutions

In this study, bindings of anionic azo dyes containing sulphonyl group such as acid red 26, acid red 103, direct yellow 9, acid black 1 and acid orange 52 onto crosslinked poly(N-vinylpyrrolidone) (CPVP) have been investigated. Adsorption of anionic azo dyes onto CPVf were studied by batch adsorption technique. In the experiments of adsorption, L (Langmuir) type adsorption in the Giles classification system was found. Binding parameters such as initial binding constant (K(i)), equilibrium constant (K); monolayer coverage (n), site-size (u), maximum fractional occupancy (theta), and thermodynamic parameters such as heat of adsorption (Delta H), free energy of adsorption (Delta G) and entropy of adsorption (Delta S) for CPVP/anionic azo dye systems were calculated using Klotz method.