Effects of DMSO Content on the Optical Properties, Liquid Stability, and Antimicrobial Activity of Fe3O4/OA/DMSO Ferrofluids

Abstract

Fe3O4 nanoparticles were synthesized through a sonochemical method and were subsequently investigated by X-ray diffraction (XRD), which showed that the phase obtained was Fe3O4 with the most intense peak at 2[Formula: see text] of 35.5∘. The particle size of the Fe3O4 nanoparticles was 11.4[Formula: see text]nm. The dried ferrofluids containing Fe3O4 as a filler, oleic acid (OA) and dimethyl sulfoxide (DMSO) as surfactants tended to be amorphous. Scanning electron microscopy (SEM) observation of the Fe3O4 nanoparticles revealed agglomeration, and the dried ferrofluids morphology showed excellent dispersion. The constituent elements of both the Fe3O4 nanoparticles and the Fe3O4/OA/DMSO ferrofluids were identified through energy-dispersive X-ray spectroscopy to be Fe, O and C. Fourier transform infrared (FTIR) investigation revealed functional groups of the Fe3O4/OA/DMSO ferrofluids constituent Fe3O4 as the filler, OA and DMSO as surfactants, and olive oil as a dispersant. The absorbance of the samples was characterized by UV–Vis spectrophotometry, and the results were used to calculate the energy gap of the Fe3O4/OA/DMSO ferrofluids ranged from 2.20[Formula: see text]eV to 2.45[Formula: see text]eV. Through the absorbance measurements, the optical properties of Fe3O4/OA/DMSO ferrofluids were evaluated on the basis of their refractive indices, which ranged from 2.86 to 3.02. The stability of the Fe3O4/OA/DMSO ferrofluids was characterized by transmittance data collected for 12[Formula: see text]h, and excellent stability was obtained, as indicated by a relatively stable transmittance. Last, the antimicrobial activity of the Fe3O4/OA/DMSO ferrofluids was assessed through the diffusion method; the results showed that increasing DMSO volume resulted in greater ferrofluid antimicrobial activity.