Magnesium-zinc ferrites as magnetic adsorbents for Cr(VI) and Ni(II) ions removal: Cation distribution and antistructure modeling

The magnesium-zinc ferrites Mg1-xZnxFe2O4 (x = 0 ... 1) were studied as magnetic sorbents for environmental applications. Low-temperature Mossbauer spectroscopy was used to determine the distribution of magnesium and ferric ions in the spinel crystal lattice. The influence of Zn content on magnetic parameters was investigated on the basis of VSM data. As the molar ratio of zinc to magnesium increases from 0 to 1, the pH(PZC) value decreases from 10.5 to 8.9. Langmuir and Freundlich models were used to check whether single-layer or multi-layer adsorption occurs. The adsorption of Cr(VI) and Ni(II) ions is well fitted by the Langmuir equation. To check the physical or chemical nature of the sorption process, the Dubinin-Radushkevich equationwas used. It was found that the processes of adsorption of Cr(VI) and Ni(II) ions are of a chemical nature. The best Cr(VI) ion adsorption capacity was found for the Mg0.2Zn0.8Fe2O4 sample (q(e) = 30.49 mg/g). The percentage of heavy metal removal by the mixed ferrite samples increases with increasing zinc content. The most effective sorbent for Ni(II) removal is the Mg0.4Zn0.6Fe2O4 sample (93.2%). Modeling the antistructure provides deeper insight into the mechanism of heavy metal adsorption. The obtained magnesium-zinc ferrites are promising magnetic adsorbents for removing chromate and nickel ions from the environment. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study investigated magnesium-zinc ferrites as magnetic sorbents for environmental applications, determining ion distribution and magnetic parameters with low-temperature Mossbauer spectroscopy and VSM data. The adsorption of Cr(VI) and Ni(II) ions showed chemical nature according to Langmuir equation, with the best adsorption capacity found in certain samples. Increasing zinc content led to higher heavy metal removal percentage in mixed ferrite samples, showing promise for heavy metal adsorption.