Preparation and characterization of new magnetic chitosan-glycine-PEGDE (Fe3O4/Ch-G-P) beads for aqueous Cd(II) removal

The growing threat to human health caused by cadmium pollution urges industry to conduct proper and efficient wastewater treatment. For that purpose, chitosan could be employed as an excellent adsorbent for the cadmium removal, however, requiring some modifications. This present work aimed to develop chitosan beads, by means of glycine grafting, PEGDE crosslinking, and magnetic Fe3O4 filler embedment. Characterizations of the prepared Fe3O4/Chitosan-Glycine-PEGDE (Fe3O4/Ch-G-P) beads were carried out using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscope (SEM). Batch adsorption of Cd2+ was optimized with parameters of contact time and solution pH. The regeneration of Fe3O4/Ch-G-P was also studied. Batch adsorption of Cd2+ on Fe3O4/Ch-G-P was found optimum after 30 min contact time at initial pH 5 with removal percentage of more than 98%. Isotherm studies suggested the adsorption was Langmuir isotherm model dependent (adjusted-R-2 = 0.992) with q(m) = 171.06 mg/g. Further investigation using three-parameters isotherm model, Sips, revealed a better fitness with adjusted-R-2 = 0.999. The experimental data followed pseudo-second-order kinetic model (adjusted-R-2 = 0.796, 0.911, and 0.981 for initial Cd2+ concentrations of 20, 25, and 30 mg/L, respectively) indicated the adsorption was determined by chemisorption. In conclusion, the addition of PEGDE improved the ability of magnetic glycine-grafted chitosan in Cd2+ removal from aqueous solution.