Effective removal of ionic dyes from aqueous media using modified karaya gum–PVA semi-interpenetrating network system.

A semi-interpenetrating network consisting of karaya gum-graft-polyacrylamide and poly(vinyl alcohol) has been developed as an adsorbent material for dye removal applications. The system was made by microwave irradiation of the aqueous mixture of karaya gum, acrylamide, N,N′-methylenebisacrylamide, and poly (vinyl alcohol); and was characterized by FTIR, TGA, SEM, and XRD techniques. It was evaluated as an adsorbent material for removal of ionic dyes from aqueous solutions. Appreciably high adsorption capacity is exhibited by the material towards cationic dyes as indicated by values of maximum adsorption capacity of 82.28, 72.94, 48.75 and 34.67 mg/g towards adsorption of cationic dyes, namely methylene blue (MB), crystal violet (CV), rhodamine B (Rh B), and toluidine blue (TB). Relatively low value of 21.66 mg/g is obtained for anionic dye indigo carmine (IC). The kinetic data of dye adsorption best fitted with the pseudo-first-order kinetic model with R2 values of 0.979, 0.989, 0.946, 0.991, and 0.986 for TB, MB, CV, Rh B and IC, respectively. The isotherm data fit well with the Freundlich model with R2 values of 0.986, 0.955, 0.990, 0.980 and 0.993 for TB, MB, CV, Rh B, and IC, respectively, indicating the heterogeneous and multilayer adsorption. The thermodynamic studies showed dye adsorption to be an exothermic and spontaneous process. [ABSTRACT FROM AUTHOR]