Control the growth of Fe3O4 on the surface of saponite and its redox effect on Cr (VI)

In this paper, Magnetite/Saponite (Fe3O4/Sap) composites were prepared by hydrothermal synthesis and co-precipitation. The prepared Fe3O4/sap composites had high purity and good crystallinity, and nano-Fe3O4 was uniformly dispersed on the surface of saponite. Moreover, the removal efficiency of Fe3O4/Sap composites for Cr (VI) in water was evaluated. This study revealed the existence of abundant oxygen vacancies and hydroxyl groups on the surface of Saponite. During the synthesis of Fe3O4 on the surface of Sap, the multi-directional crystallization can be controlled to increase the reaction activity of the system. Besides, the prepared Fe3O4/Sap composites provided more reactive edges compared to Fe3O4 in the process of removing Cr (VI). The removal amount of Cr (VI) was found to be 17.95 ​mg/g. The successful preparation of the Fe3O4/Sap composites and the revelation of the Cr (VI) adsorption mechanism are of great significance for the efficient and green removal of heavy metal pollutants in sewage.