Chelating magnetic nanocomposite for the rapid removal of Pb(ii) ions from aqueous solutions: characterization, kinetic, isotherm and thermodynamic studies

Abstract

In this study, a Fe3O4@GMA-AAm magnetic nanocomposite was synthesized as a novel adsorbent with a suitable core-shell structure, high adsorption capacity (158.73 mg g−1), easy separation and rapid adsorption rate. For this purpose, Fe3O4 NPs were first reacted with 3-aminopropyltriethoxysilane for the preparation of MNPs-NH2. Then the MNPs-NH2 was allowed to react with glycidylmethacrylate to form Fe3O4-GMA. Finally Fe3O4@GMA-AAm was synthesized by grafting polyacrylamide onto the Fe3O4-GMA using a radical polymerization process. The morphology and characteristics of the adsorbent were examined by various techniques such as FT-IR, TEM, SEM, XRD, AFM, TGA, EDX, EMA and VSM analysis. The synthesized adsorbent was used for the removal of Pb2+ ions from aqueous media and the effect of different parameters (pH, adsorbed dosage, temperature, etc.) was investigated. The isotherm analysis indicated that the adsorption experimental data fitted very well with the Langmuir isotherm model. Two kinetics equations were used to describe the adsorption rate. The result showed that the pseudo-second-order model had a better fit with the experimental data, so the chemical adsorption was the rate controlling step of the adsorption process. The thermodynamic parameters for adsorption of Pb2+ ions onto the Fe3O4@GMA-AAm adsorbent showed that the adsorption was endothermic in nature and spontaneous.