The high efficient Sb(III) removal by cauliflower like amorphous nanoscale zero-valent iron (A-nZVI)

In this study, cauliflower like amorphous nanoscale zero-valent iron (A-nZVI) was prepared and its performance on the removal of Sb(III) was investigated and compared with that of nZVI. The results indicated that the removal of Sb(III) by nZVI and A-nZVI followed the pseudo-second-order kinetic model and Langmuir isotherm model, but the removal of Sb(III) by A-nZVI was more stable and its removal capacity (558.2 mg/g) is much higher than that of nZVI (91.3 mg/g). Moreover, the effects of initial Sb(III) concentration, initial pH and anions such as Cl^-, NO₃^-, SO₄^2-, PO₄^3-, and AsO₄^3- were also investigated. A-nZVI showed extremely high selectivity towards Sb(III) in that 500 mg/L of AsO₄^3- and PO₄^3- shows little impact on its removal, while the removal of Sb(III) by nZVI was almost inhibited under the same condition. The combination of SEM-EDS, XPS, XRD and FTIR revealed the removal of Sb(III) by nZVI and A-nZVI were synergistic effects of oxidation and adsorption, but less Sb(III) (39.5%) was oxidized by A-nZVI. More γ-FeOOH and γ-Fe₂O₃ were formed at the surface of A-nZVI during the reaction. Both oxides have high affinity toward Sb(III), which might cause the higher removal capacity and selectivity for the removal of Sb(III) by A-nZVI. In conclusion, A-nZVI showed great potential for the remediation of Sb(III) in groundwater.