Abstract

In this work, a novel environmentally friendly semi-interpenetrating anionic hydrogel based on Xanthan gum/cross-linked polyacrylic acid/graphene oxide was prepared as superabsorbent for removing methylene blue as cationic dye from the water. Acrylic acid (AA) was crosslinked in xanthan (XG)/graphene oxide (GO) solution by a novel synthetic acrylic-urethane crosslinker (MS). Various analyses such as SEM, FT-IR, H-1 NMR, XRD, and TGA were used to study morphology, structure, and thermal stability of MS and semi-IPNs. The synthesized hydrogels showed pH-sensitive behavior in water uptake, with the highest and lowest swelling in alkaline and acidic media, respectively. The nanocomposites had better dimension stability and dye adsorption with increasing GO from 0 to 1. Hydrogel containing 1 GO showed 485 and 885 swelling and dye adsorption efficiency, respectively. Different kinetic models including 1st order, 2nd order, infra-particle diffusion, and Elovich kinetics were studied. All models except 2nd order model are in good agreement with the experimental data. GO-containing hydrogels had a significant effect on methylene blue adsorption and this effect increased with an increase in the amount of GO. PAA/XG/GO hydrogels can be introduced as an eco-friendly adsorbent with high efficiency for the removal of cationic dye pollutions. (C) 2020 Elsevier B.V. All rights reserved.