Facile fabrication of Cu(II) coordinated chitosan-based magnetic material for effective adsorption of reactive brilliant red from aqueous solution.

In order to effectively remove reactive brilliant red (RBR) in aqueous solution, a novel Cu(II) coordinated chitosan-based magnetic composite (CTS-Cu@SiO2@Fe3O4) was prepared. The physicochemical properties of the resultant adsorbent were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) thermogravimetric (TG) analysis, scanning electron microscopy (SEM) and N2 adsorption-desorption. The adsorption capacity toward RBR was systematically investigated as a function of contact time, solution pH, initial concentration, ionic strength and temperature. Compared with CTS@SiO2@Fe3O4, CTS-Cu@SiO2@Fe3O4 showed better adsorption performance in removing RBR, reaching a maximum of 880.84 mg/g at pH 4, which confirmed that the coordination of Cu(II) can improve the adsorption capability. The adsorption kinetics of CTS-Cu@SiO2@Fe3O4 was found to follow the pseudo-second-order kinetic model, and the equilibrium adsorption data were well described by the Freundlich isotherm model. Thermodynamic studies indicated that the adsorption process was spontaneous and endothermic. XPS analysis confirmed that the adsorption was mainly controlled by electrostatic interaction between copper/amino cation and RBR anion. Furthermore, regeneration experiments demonstrated that CTS-Cu@SiO2@Fe3O4 can be used repeatedly. In a word, CTS-Cu@SiO2@Fe3O4 can be served as a promising adsorbent for dye wastewater scavenging.