Structural and magnetic studies of NiFe2O4 and NiFe2O4@SiO2-Silane agent samples useful for the removal of Cu2+ ions

Abstract

Nickel ferrite samples are currently investigated due to their potential technological applications. For this reason, the optimal synthesis conditions of nickel ferrite samples with small particle size were investigated here. First, a systematic study was carried out using urea as an additive, and varying reaction parameter such as the amount of urea added or the reaction temperature and time. For comparison purposes, another sample was synthesized using potassium hydroxide as an additive. The two pure nickel ferrite samples were coated with silica, functionalizing them with APTES and AEPMDS. X-rays, FTIR, Mössbauer spectroscopy, TEM and Ms vs. H and FC/ZFC curves were used for the characterization of samples and the evaluation of their properties. Square particles with an average size of 21.2 nm were observed in the TEM images of the sample synthesized with urea, while these are spherical of 6.2 nm in the sample prepared with potash. Their subsequent coating and functionalization give rise to an arrangement of particles within interlocking strands whose thickness increases with their size. Ms vs. H curves confirm the almost superparamagnetic behavior of all synthesized powders, although with a slight increase in the coercivity value of the samples prepared with urea. Preliminary tests carried out on the functionalized samples to evaluate the adsorption capacity in aqueous solution and their easy separation in presence of an external magnetic field, confirm that the sample syn thesized with urea and functionalized with AEPDMS is the most efficient for the Cu2+ ions removal.