Adsorption of phenazine dyes using poly(hydroxamic acid) hydrogels from aqueous solutions

Swelling and adsorption properties of poly(hydroxamic acid), (PHA) hydrogels in aqueous solutions of some phenazine dyes such as Neutral Red, Safranin T, and Janus Green have been investigated. PHA hydrogels containing N,N methylenebisacrylamide or ethyleneglycoldimethacrylate were used in experiments on swelling, diffusion and adsorption of the dyes. The equilibrium swelling (S-eq) values of PHA hydrogels in aqueous solutions of the phenazine dyes were calculated as 2.16-33.25 g g(-1). Swelling kinetic parameters such as initial swelling rate, swelling rate constant, and maximum swelling were found. Dye diffusion into hydrogels was found to be non-Fickian in character. Diffusion coefficients are ranged 1.32 x 10(-6) cm(2) s(-1) - 44.70 x 10(-6) cm(2) s(-1). Adsorption of the phenazine dyes onto PHA hydrogels was studied by batch technique. PHA hydrogels in the phenazine dye solutions showed the dark coloration. The data was found that Freundlich isotherm model fits. According the Freundlich constants, the adsorption isotherms are of S-type in Giles classification. All swelling and binding parameters for PHA-EGDMA were found to be higher than those for PHA-NNMBA. The type of crosslinker influenced the swelling, binding, and sorption more than the type of dye. Finally, it can be said that PHA hydrogels may be used a sorbent for removal of dyes. POLYM. ENG. SCI., 58:310-318, 2018. (c) 2017 Society of Plastics Engineers