Silver nanoparticles embedded pectin-based hydrogel: anovel adsorbent material for separation of cationic dyes

Free radical polymerization of mixture of 2-acrylamido-2-methylpropanesulfonic acid and Pectin in the presence of N,N-methylenebisacrylamide resulted in the cross-linked graft copolymer network (Pec-g-PAMPS). Silver nanoparticles were formed and stabilized by the reduction of silver nitrate using trisodium citrate within the gel network. The hydrogel and the nanocomposite hydrogel were characterized using FTIR, TGA, XRD, SEM, EDS and TEM techniques and evaluated for removal of methylene blue from aqueous solution. The presence of Ag NPs is observed to enhance the swelling ability of the Pec-g-PAMPS gels significantly. The kinetics studies indicated the adsorption to be a second-order process and the adsorption rate was influenced by intraparticle diffusion. The adsorption isotherm was in good agreement with Freundlich model suggesting surface heterogeneity of the novel adsorbent. Further, the thermodynamic studies revealed the adsorption to be a spontaneous and exothermic process. The nanocomposite hydrogel retained 80% efficiency after three cycles indicating reusability for waste water treatment.