Adsorption and Microscopic Analysis of Arsenate Uptake by Magnetic Fe Nanoparticles: a Detailed Study on Coexisting Anions Effects

Yusuf O. Zubair, Shigeshi Fuchida, Chiharu Tokoro*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Magnetic Fe nanoparticles have the potential to treat As(V)-contaminated water. However, the effects of coexisting anions on the As(V) adsorption mechanism need further investigation. The batch adsorption experimental results obtained at pH 5 and room temperature were well represented by the mixed-order kinetic, and the sips isotherm models, indicating that surface adsorption dominated As(V) removal via chemical process onto a heterogeneous surface. The surface adsorption rate of As(V) was reduced in the single-anion systems, and this resulted in a decrease in the maximum sorption density (qm) of magnetic Fe nanoparticles for As(V) (74.9 mg/g) in the following order: H2PO4 (31.3 mg/g) > H4SiO4 (47.0 mg/g) > HCO3 (50.9 mg/g) > SO42− (54.9 mg/g) > Cl (65.5 mg/g). The presence of Ca2+ in the multiple-anion system reduced the interference of coexisting anions (qm = 60.2 mg/g), possibly due to the formation of multiple Fe–As–Ca–As complexes. The results obtained from the electrophoretic mobility, FT-IR, and XPS indicated that the effects of coexisting anions on the adsorption mechanism of As(V) were driven by competitive surface complexation and redox reaction. The redox transformation of As(V) to As(III) was large in the single-anion system containing HCO3 (44.8%), SO42− (44.1%), and H4SiO4 (41.5%) because competing anions may form stable complexes with ≡Fe3+ site of magnetite, thereby enhancing the reduction of As(V) to As(III) on ≡Fe2+ site of magnetite. These findings expand the insight of As(V) uptake by magnetic Fe nanoparticles and help in predicting its performance in actual wastewater.

Original languageEnglish
Article number484
JournalWater, Air, and Soil Pollution
Issue number12
Publication statusPublished - 2022 Dec


  • Arsenic(V)
  • Coexisting anions
  • Competitive adsorption
  • Multiple complexations
  • Redox reaction

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Ecological Modelling
  • Water Science and Technology
  • Pollution


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