Facile fabrication of functional chitosan microspheres and study on their effective cationic/anionic dyes removal...

This study provided a simple one-step chemical process for the preparation of aminated magnetic chitosan microspheres (TETA-MCTSms), which were applied for adsorbing anionic dye reactive brilliant red (RBR). Meanwhile, magnetic grafted microspheres (MCTSms-PMAA) were prepared based on magnetic chitosan microspheres via a surface-initiating system NH₂/S₂O₈^2-, for adsorbing cationic dye methylene blue (MB). The physical properties and structure of the obtained microspheres were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA), and their adsorption performance for removal of cationic dye MB and anionic dye RBR was also investigated. MCTSms-PMAA performed excellent performance for cationic dye MB, represented by the adsorption capacities reaching a maximum of 211.22 mg·g^-1 at pH 12; TETA-MCTSms performed remarkable adsorption properties for anionic dye RBR, represented by the adsorption capacities reaching a maximum of 637.41 mg·g^-1 at pH 2. The kinetic analyses and equilibrium adsorption behaviors of dye wastewater onto chitosan microspheres were investigated using various models. The adsorption mechanism was further analyzed by X-ray photoelectron spectroscopy (XPS), and it was found that the adsorption was mainly driven by hydrogen bonding and electrostatic interaction.