Heavy Metal Ions Removal from Aqueous Solution using NiZnFe2O4/TiO2 Nanocomposites Adsorbent

Abstract

This research explores the adsorption effectiveness of NiZnFe2O4/TiO2 nanocomposites regarding Cr(VI). The nanocomposites were effectively synthesized utilizing coprecipitation and Stöber methods, incorporating diverse molar ratios of TiO2. The samples were subjected to characterization using methods such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), Fourier-transform infrared (FTIR), vibrating sample magnetometer (VSM), and ultraviolet-visible spectroscopy (UV-Vis). These analyses were conducted to evaluate the crystal structure, morphology, chemical bond formation, optical properties, magnetic properties, and removal efficiency of the specimens. XRD results showed that NiZnFe2O4 and TiO2 have a cubic and tetragonal structure. The crystallite size decreased as the TiO2 concentration increased. TEM image of NiZnFe2O4 reveals the formation of clusters, indicating uneven dispersion under agglomerated conditions. The average particle size is measured at (10.6 ± 0.8) nm. The Fourier-transform infrared (FTIR) analysis demonstrated the presence of functional groups O-H, C-H, and H-O-H, indicating the successful synthesis of the material. Moreover, the identification of MO-octahedral, MO-tetrahedral, and Ti-O functional groups suggested the formation of NiZnFe2O4/TiO2 nanocomposites. The incorporation of TiO2 had an impact on both the saturation magnetization and coercivity values, which fell within the ranges of 12.4 to 22.9 emu/g and 47 to 55 Oe, respectively. This finding indicates the presence of advantageous magnetic properties. The absorbance spectrum of these nanocomposites displayed a shift to the right (redshift), allowing them to absorb ultraviolet rays. The band gap of these nanocomposites ranges from (2.85 ± 0.02) to (3.29 ± 0.02) eV. Notably, NiZnFe2O4/TiO2 nanocomposites with a concentration ratio of 1:5 exhibit effective Cr(VI) removal efficiency, achieving a degradation value of 65.6%. The pseudo-kinetic model was first investigated to describe kinetic data and Cr(VI) removal determination. The SEM-EDX adsorbent results after adsorption showed the presence of Cr(VI) in the nanocomposites. Therefore, these results can promote NiZnFe2O4/TiO2 nanocomposites as a promising candidate in the removal of heavy metal waste.