Preparation of MO.Fe2O3 , M=Fe2+, Zn2+and Mg2+, nanoferrites and investigation of their optical and structural properties

Taami, Elahe and Azizian-Kalandaragh, Yashar and Tavana, Ali (2018) Preparation of MO.Fe2O3 , M=Fe2+, Zn2+and Mg2+, nanoferrites and investigation of their optical and structural properties. Masters thesis, University of Mohaghegh Ardabili.

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Abstract

Research Aim: In this research, Iron, Zinc and Magnesium nanoferrites have been prepared by ultrasounic waves without any annealing. Then, the photocatalytic properties of the prepared nanostructures have been done for removing methylene blue from drinking water. Research method: Using ultrasounic waves the preparation of nanostructured materials are possible. when colloidal particles in the liquid medium kept under ultrasounic waves, the collision between the waves, water, and particles generates very small bubbles and the small bubbles growth, then collapse, and the impulses from bubble collapse causing formation of colloidal nanostructures. Findings: XRD pattern of the prepared nanostructures show that Fe, Zn and Mg Ferries have been formed with crystalline cubic spinel structure. The mean particle size of Iron, Zinc and Magnesium Ferrite have been calculated by Debye-Scherrer equation, and are 13, 7 and 6 nm, respectively. Scanning electron microscopy results shows that the nanostructures sizes are less than 20 nm, and the cluster sizes are between 50 to 200 nm, in all cases. Magnesium ferrites have direct band gap and iron and zinc ferrites have both direct and indirect band gap. The values of band gaps for direct transitions of magnesium ferrites are equal to 2.8eV and for iron and zinc for direct transition are 2.2eV and 2.3eV, respectively and for indirect transition for both of structures are 1.4ev. The analysis of vibrating sample magnetometery(VSM) of the samples shows that the saturation magnetization for Iron Ferrites, Zinc and Magnesium are 66emu/g, 20emu/g and initial values 0.00274emu/g, respectively. The removing of MB from water using Iron Ferrite nanostructures after 90min are 60% degradation, in the case of Zinc Ferrite are 98% degradation in 60 min and 99% degradation in 45 min by Magnesium Ferrites were investigated by measuring the photocatalytic activity of the prepared ferrites. Conclusion: In the prepared nanostructures, by decreasing particle sizes from 13 to 6nm we observed an increasing in band gap energy from 2.2eV to 2.8eV and also by decreasing the particles size in nanostructures, the photocatalytic activities increases over several times. In other words, Iron Ferrite nanostructures with average particle sizes about 13nm, removes 60% of MB in 90min and Magnesium Ferrite nanostructures with average particle size about 6 nm, removes 99% of MB in 45min. which, this increasing in photocatalytic activity was expected by decreasing in nanostructure sizes and increasing in surface to value ration.

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