Removal of some textile dyes from aqueous solutions by poly(N-vinyl-2-pyrrolidone) and poly(N-vinyl-2-pyrrolidone)/K2S2O8 hydrogels

Poly(N-vinyl-2-pyrrolidone)/water and poly(N-vinyl-2-pyrrolidone)/K2S2O8/water systems are hydrogels prepared by irradiation with gamma-rays at ambient temperature. Both hydrogel systems were employed for diffusion and swelling experiments in various textile dyes aqueous solutions (textile dyes such as Cibacron Blue (CB) F3GA, Methyl Orange (MO), Congo Red (CR)). For these hydrogel systems, swelling studies indicated that swelling percentages increased in the following order: MO > CB F3GA > CR at fixed dose 96 kGy. Because of this reason MO dye solution has been chosen and all swelling properties are investigated for 26, 64, 96 and 124 kGy. The swelling capabilities of PVP and PVP/K2S2O8 hydrogels in MO dye solution vary in the range of 400-1500%. The diffusion of dye solutions PVP and PVP/K2S2O8 hydrogels was assumed to be Fickian character. The swelling behavior of PVP and PVP/K2S2O8 hydrogels exhibits second-order kinetic in all dye solutions. Diffusion coefficient, initial swelling rate, swelling rate constant, maximum swelling and equilibrium water/dye content were found for all gel systems in dye solutions. (C) 2003 Elsevier Ltd. All rights reserved.