New insight in adsorption of Sb(III)/Sb(V) from waters using magnetic nanoferrites: X-ray absorption spectroscopy investigation

• Published in: Journal of molecular liquids Vol. 330; p. 115691
• Main Authors: Tu, Yao-Jen, Wang, Shan-Li, Lu, Ying-Rui, Chan, Ting-Shan, Johnston, Cliff T.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.05.2021
• Subjects: Antimony; EXAFS; Magnetic nanoferrites; X-ray absorption spectroscopy; XANES; Antimony; X-ray absorption spectroscopy; XANES; EXAFS; Magnetic nanoferrites
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2021.115691

Antimony (Sb) is widely used in many agricultural and industrial application. However, Sb contamination can threaten ecosystem and human health. This study attempts to find a simple and fast way in removing Sb, especially for severely toxic Sb(III) from waters. Six kinds of magnetic nanoferrites (CuFe2O4, MnFe2O4, CoFe2O4, NiFe2O4, ZnFe2O4, Fe3O4) were synthesized to investigate their ability in removing Sb(III) and Sb(V) from aquatic systems. Sb K-edge XANES spectra indicated that Sb(V) was adsorbed on the surface of ZnFe2O4 and would not be converted to more toxic Sb(III). Contrarily, Sb(III) was observed to be adsorbed on ZnFe2O4 and ZnFe2O4 could oxidize Sb(III) to Sb(V). O K-edge XANES analyses showed the downswing of Fe 3d-O 2p characteristic peak after adsorption, which proved again that ZnFe2O4 had the great potential to adsorb and oxidize Sb(III) in aqueous solutions. EXAFS revealed that the peaks on k-space and R-space were quite different, implying that Sb(III) and/or Sb(V) did not replace Fe and/or Zn during the adsorption process. Additionally, XRD spectrum showed that after adsorption of Sb(III) and/or Sb(V), the structure of ZnFe2O4/Fe3O4 remained as fcc spinel structure (Fd-3m), indicating that these nanoferrites possessed good structural stability. This study provided essential information for designing a rapid and effective Sb removal technique in treating Sb-contaminated river water, tap water, and groundwater. [Display omitted] •Fast and efficient removal of Sb from real water systems was achieved by ZnFe2O4.•Sb K-edge XANES showed the adsorbed Sb(III) could be oxidized to less toxic Sb(V).•K-edge XANES proved again that Sb(III) can be converted to Sb(V) by ZnFe2O4.•EXAFS confirms that Sb did not replace Fe or Zn in the spinel structure of ZnFe2O4.•More than 97.3% nanoferrites can be efficiently and rapidly recovered in 20 s.