Efficient Removal of Cr (VI) and As (V) from Aqueous Solution Using Magnetically Separable Nickel Ferrite Nanoparticles

Abstract

A promising nickel ferrite (NiFe₂O₄) NPs with excellent magnetic characteristics was synthesized using an aqueous-based reflux approach that eliminates the need for calcination temperature. The magnetic nanoparticles obtained were analysed using X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and scanning electron microscopy (SEM). The analysis showed that synthesized nickel ferrite had a spherical shape with an average size ranging from 18 to 29 nm. The synthesized nickel ferrite is utilized for the removal of hexavalent chromium (Cr (VI)) and pentavalent arsenic (As (V)) ions from aqueous solution through adsorption method. The removal of Cr (VI) ions achieved a maximum efficiency of 65% after 120 minutes at a pH of 5, with a ferrite dose of 2 g/L and a concentration of Cr (VI) ions of 25 mg/L. while the removal of As (V) at a pH of 5, with a dose of 1 g/L of ferrite and an initial concentration of 25 mg/L of As (V) ions was 77% after 120 minutes. In addition, the data obtained from the isotherms of Langmuir (R² = 0.99, 0.98), Freundlich (R² = 0.86, 0.97) and Temkin (R² = 0.83, 0.97). The adsorption of Cr (VI) ions is governed by a pseudo first-order kinetics process, whereas the adsorption of As (V) ions is governed by a pseudo second-order kinetics reaction. After five adsorption–desorption cycles at the same optimal operating condition, Cr (VI) and As (V) removal efficiency dropped from 65%, 77% to 25%, 30%, respectively.