Preparation, Characterization and Adsorption Study of PEDGE-Cross-linked Magnetic Chitosan (PEDGE-MCh) Microspheres for Cd2+ Removal

To enhance the ability and practicality of chitosan used for wastewater treatment, this study aimed to modify chitosan through cross-linking and addition of magnetic properties. Cross-linked magnetic chitosan microspheres were prepared using the inverse phase dispersion method and then applied for Cd2+ removal from water. Fe3O4 nanoparticles prepared from local iron sand were embedded with chitosan cross-linked by polyethylene glycol diglycidyl ether (PEDGE) to produce PEDGE cross-linked magnetic chitosan (PEDGE-MCh) microspheres. PEDGE-MCh microspheres were characterized by Fourier transform infrared, scanning electron microscopy energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses. Altogether, the characterization confirmed the formation of cross-linking and the interaction among components in the adsorbent. Additionally, the characterization also revealed the additional features of functional groups, rougher surface, and more amorphous properties beneficial in pollutant removal. Further, the batch adsorption experiments suggest that the cross-linking and addition of Fe3O4 improved the adsorption capacity. The highest adsorption capacity was obtained at pH 5 with a contact time of 40 min. Adsorption isotherm studies indicated that the Cd2+ adsorption onto PEDGE-MCh microsphere was Redlich-Peterson dependent (R2 = 0.9996 and root-mean-square errors = 0.064). The regeneration remained the primary challenge of PEDGE-MCh application in the wastewater treatment.