Development of a magnetic core-shell Fe3O4@TA@UiO-66 microsphere for removal of arsenic(III) and antimony(III) from aqueous solution

Removal of trivalent species of As and Sb from wastewater is crucial due to their more toxic and mobile properties. In this study, a novel magnetic core-shell microsphere Fe3O4@TA@UiO-66 was developed via in-situ crystal growth of UiO-66 around the magnetic Fe3O4 modified by Tannic Acid (TA). Characterization of the microsphere by transmission electron microscopy (TEM) and X-ray diffraction spectroscopy (XRD) confirmed that UiO-66 was adhered on the surface of Fe3O4 functionalized by TA. Adsorption experiments showed that the magnetic Fe3O4@TA@UiO-66 had high adsorption capacity for As(III) and Sb(III) and could be rapidly separated from aqueous media within two minutes after treatment. The adsorption kinetics and adsorption isotherms were described well by the pesudo-second order model and Langmuir model, respectively. In addition, the composite exhibited excellent removal performance for As(III) and Sb(III) in a broad solution chemistry environment, including pH and co-existing anions. Based on X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) measurement, we proposed that the removal mechanism was mainly controlled through a synergistic interaction of surface complexation and hydrogen bonding. This study indicates the potential of the magnetic microsphere to be used as an effective material for the removal of As(III) and Sb(III) from water.