A facile sol combustion and calcination process for the preparation of magnetic Ni0.5Zn0.5Fe2O4 nanopowders and their adsorption behaviors of Congo red

Abstract

A facile sol combustion and calcination process for the preparation of magnetic Ni0.5Zn0.5Fe2O4 nanopowders was introduced and the gel precursor and as-prepared nanopowders were characterized by TG/DSC, XRD, BET, SEM and TEM. The results have shown that the single ferrite phase of Ni0.5Zn0.5Fe2O4 can be formed at 400°C. It can be indicated that the volume of the solution is a key factor to the properties of the magnetic Ni0.5Zn0.5Fe2O4 nanopowders: with the volume of absolute alcohol increasing from 10mL to 30mL, the average grain sizes of Ni0.5Zn0.5Fe2O4 powders calcined at 400°C for 2h with the heating rate of 3°C/min increase from about 14.9nm to 18.3nm, while the saturation magnetizations increase from about 27.1Am2/kg to 105.2Am2/kg, and the specific surface area is up to maximum of 69.7m2/g when absolute alcohol is 15mL. The adsorption kinetics and adsorption isotherm of Congo red (CR) onto the magnetic Ni0.5Zn0.5Fe2O4 nanoparticles calcined at 400°C for 2h with a heating rate of 3°C/min and absolute alcohol of 15mL were investigated at room temperature. The kinetic data related to the adsorption of CR from aqueous solutions are in good agreement with the pseudo-second-order kinetic model with a range of initial concentrations of 100–500mg/L. Compared with Langmuir and Freundlich models for adsorption isotherm of CR, Temkin model (correlation coefficient R2=0.9937) can be used to evaluate the CR adsorption isotherm at room temperature.