Efficient As(V) Removal by Recyclable Composite Nickel–Iron Oxide (NiFe 2 O 4 ) Derived from NiFe Layered Double Hydroxides In situ Growing on Nickel Foam

A recyclable NiFe 2 O 4 was synthesized and applied to the removal of As(V) from arsenic-contaminated solutions by calcining Ni/Fe layered double hydroxides (LDHs) through in situ growing on nickel foam (NF). The NiFe-LDHs/NF and NiFe 2 O 4 /NF exhibited typical hierarchically porous platelet-like structures. The adsorption kinetics, isotherms, and adsorption mechanism of As(V) on NiFe 2 O 4 /NF were studied in detail. The thermodynamic parameters of the adsorption process were calculated, and the regeneration ability and stability of NiFe 2 O 4 /NF were investigated. The positive Δ H value (6.36 kJ mol −1 ) and negative Δ G value (< − 25.8 kJ mol −1 ) confirm that the As(V) adsorption on the NiFe 2 O 4 /NF is an endothermic and spontaneous process. The adsorption mechanism can be interpreted as the surface complexation between As(V) and NiFe 2 O 4 /NF. After ten adsorption/desorption cycles, the NiFe 2 O 4 /NF still exhibits excellent adsorption performances. The stability experiments showed that no Fe leaching was detected and the Ni 2+ leaching concentration was about 7 μg L −1 , which was much lower than the Chinese drinking water standard (20 μg L −1 ), indicating that NiFe 2 O 4 /NF is a potential adsorbent for As(V)-contaminated drinking water treatment.