High stable suspension of magnetite nanoparticles in ethanol by using sono-synthesized nanomagnetite in polyol medium

• The sonochemical synthesis of magnetite nanoparticles was carried out in EG without any surfactant.
• The nanoparticles with sizes ∼24 nm were composed of small building blocks with sizes ∼2 nm.
• The hydrophilic magnetite nanoparticles were stable in ethanol even after 8 months.
• Ultrasonic intensity showed a crucial role on the obtained high stable magnetite nanoparticles in ethanol.

The sonochemical synthesis of magnetite nanoparticles was carried out at relatively low temperature (80 °C) in ethylene glycol (EG) as a polyol solvent. The particle size was determined by transmission electron microscopy (TEM). The magnetite nanoparticles with an average size of 24 nm were composed of small building blocks with an average size of 2–3 nm and the particles exhibited nearly spherical shape. The surface characterization was investigated by using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The stability of magnetite nanoparticles was studied in ethanol as a polar solvent. The nanoparticles showed an enhanced stability in ethanol which is due to the hydrophilic surface of the particles. The colloidal stability of magnetite nanoparticles in ethanol was monitored by UV–visible spectrophotometer. According to the results, the nanoparticles synthesized in 30 min of sonication with intensity of 35 W/cm2 (50%) led to a maximum stability in ethanol as a polar solvent with respect to the other applied intensities. The obtained magnetite nanoparticles were stable for more than12 months.

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