Tuning the Interfacial Properties of Spinels to Improve the Antimony Adsorption Ability

Structure and interfacial properties are important factors that affect a spinel's adsorption performance. In this article, by changing the water content in a precursor during synthesis, the interfacial properties of normal and inverse spinels were tuned to improve Sb adsorption. The results showed that changing the water content did not alter the crystal structure of synthesized zinc ferrite (ZnFe₂O₄) and cobalt ferrite (CoFe₂O₄), but it had a significant effect on the crystallite size and the number of surface hydroxyl groups. For normal spinel ZnFe₂O₄ and inverse spinel CoFe₂O₄, the crystallite size decreased while the surface hydroxyl groups increased when the water content gradually increased from 1 to 8 mL. Spinels with smaller crystallite size and more surface hydroxyl groups enhanced Sb adsorption. The adsorption capacity of ZnFe₂O₄ and CoFe₂O₄ for low concentrations of Sb(V) increased from 8.45 and 10.64 mg/g to 15.05 and 17.00 mg/g, respectively. This work has greatly improved the adsorption capacity of spinel materials through a simple tunable method and is expected to provide new ideas for the interfacial tuning of spinel materials, which shows great potential applications for wastewater treatment.