Simultaneous oxidation and removal of Sb(III) from water by using synthesized CTAB/MnFe₂O₄/MnO₂ composite

Low levels of antimony (Sb) can be effectively removed from water by adsorption onto various materials, and searching for low-cost and high-efficiency new adsorbents has been a hot topic in recent years. In the present study, the performance of cetyltrimethylammonium bromide (CTAB) modified MnFe₂O₄/MnO₂ composites (CTAB/MnFe₂O₄/MnO₂) as an adsorbent for Sb(III) removal from aqueous solution was investigated. Kinetic study revealed that adsorption of Sb(III) by CTAB/MnFe₂O₄/MnO₂ was fast in the first 430 min and the equilibrium was achieved within 1440 min. The adsorption kinetic data were well fitted with pseudo-second-order model. The maximum adsorption capacity of the synthesized adsorbent for Sb(III) at pH 7 calculated from Langmuir adsorption isotherms in batch experiments was 321.03 mg g^-1. During the adsorption process, Sb(III) can be simultaneously oxidized to Sb(V) and the average oxidation percentage reached 95.43% within 1440 min. The adsorption capacity did not significantly vary with pH. Common metal cations (Ca²⁺ and Mg²⁺) slightly enhanced Sb(III) adsorption at pH 7. In comparison, the effect of anions (Cl^-, NO₃^-, and PO₄^3-) on Sb(III) adsorption was not obvious. The results suggest that CTAB/MnFe₂O₄/MnO₂ is a potential cost-effective adsorbent for Sb(III) removal in water treatment.