Ultrasmall Cu-Substituted NiZn Ferrite Nanoparticles: Efficiency for the Removal of the Alizarin Red S Dye and Reusability

A series of Cu-substituted NiZn ferrite nanoparticles (Ni0.5Zn0.5-xCuxFe2O4; 0 <= x <= 0.2) were synthesized by the polyol method and then characterized and investigated for their efficiency for the adsorptive removal of Alizarin Red S (ARS) dye as well as for their reusability. The effect of Cu2+ substitution for Zn2+ on the phase formation, crystal structure, microstructure and magnetic properties was investigated. The powders were pure phases with a cubic spinel structure and a slight departure of the unit cell parameter from the expected linearity variation as a function of Cu-2 content. The particles are ultrasmall sized nanoparticles (similar to 4-6 nm) with an almost spherical shape. The surface chemistry and the core local structure of the nanoparticles were ascertained from infrared. Magnetic study revealed a superparamagnetic behavior, and the variation observed for the main magnetic characteristics was interpreted on the basis on the changes in chemical composition, cation distribution and nanoparticles morphology. Adsorption-desorption of ARS onto the nanoparticles was investigated by varying various physicochemical parameters. The ferrite member with x = 0.15 exhibited the best removal capacity. At the optimum pH (pH2.0) the adsorption was fast during the first stage of adsorption process. Three kinetic models were tested. The adsorption data were best fitted with the pseudo-second-order model. The adsorption isotherms were measured and analyzed by Langmuir and Freundlich models. Based on Freundlich model, the maximum adsorption capacity was found to be high (similar to 181 mg g(-1)). Besides, good reusability performance was observed after five adsorption-desorption-regeneration cycles. The mechanisms of both adsorption and desorption were proposed.

Automated summary

Cu-substituted NiZn ferrite nanoparticles were synthesized and investigated for their efficiency in removing ARS dye through adsorption. The effects of Cu2+ substitution for Zn2+ on various properties were studied. The nanoparticles exhibited a cubic spinel structure, ultrasmall size, and superparamagnetic behavior. The highest removal capacity was observed for the ferrite member with x = 0.15. Adsorption-desorption studies showed good reusability after multiple cycles. The adsorption data were best fitted with the pseudo-second-order model, and the maximum adsorption capacity was high according to the Freundlich model.