Enhanced trapping of Ni(II) ions by diatomite-supported nanoscale zerovalent iron from aqueous solution

This study investigated the effective trapping of Ni(II) ions by nanoscale zerovalent iron (NZVI) and diatomite-supported NZVI (NZVI-D) nanoparticles prepared via a borohydride reduction method. The confinement of iron crystal growth on the surface of diatomite leads to the formation of NZVI, resulting in the decreased aggregation and oxidation of iron nanoparticles, which can be proved by the analysis of structure, morphology and iron species. The batch experimental results indicated that the removal of Ni(II) by NZVI-D was higher than that by bare NZVI. Both the NZVI and NZVI-D displayed dual role namely adsorption and reduction during Ni(II) removal process. The presence of diatomite also improves the reducing capacity of NZVI by preventing agglomeration of NZVI, thus increasing its reactive surface area. This can be proved by the X-ray absorption fine structure analysis, which indicated that more Ni(II) ions can be reduced into Ni(0) by NZVI-D. This NZVI-D composite has potential applications in cleaning up environmental toxic metals like Ni(II) from wastewater.