Abstract
Magnetite and silica-coated magnetite (Fe3O4) nanoparticles (NPs) were synthesized by water-in-oil (W/O) microemulsion method from hydrated ferric nitrate, ferrous sulfate precursors and ammonia a precipitating agent with the assistance of Tween-80 and SDS surfactants. The synthesized materials were characterized by X-ray diffraction, scanning electron microscopy, thermal analyzer, and infrared spectroscopy. X-ray diffraction pattern of Fe3O4 showed that particles were phase pure with a cubic inverse spinel structure and FT-infrared spectra confirmed the presence of Fe-O bond in tetrahedral and octahedral interstitial sites. The crystallite size determined from powder XRD data with Scherer's equation was in the range of 7.3 ± 0.05 nm–10.83 ± 0.02 nm for uncoated Fe3O4 and 16 ± 0.14 nm for silica-coated Fe3O4 NPs. The SEM micrographs of the uncoated Fe3O4 oxide revealed the agglomeration of the magnetite (Fe3O4) particles. But the silica-coated Fe3O4 oxide exhibited homogeneous distribution of particles with relatively less agglomerate of the particles. The particle size of Fe3O4 NPs slightly increased with the temperature and precursor concentration. The antimicrobial activities of Fe3O4 and silica-coated Fe3O4 nanoparticles were tested against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Both Fe3O4 and silica-coated Fe3O4 NPs demonstrated better antimicrobial activities.
Highlights
Nanoscience and nanotechnologies are attracting the interest of researchers and technologists in several fields for the development of nanoscale materials and devices with new properties and functions
3.1.1. ermogravimetric Differential ermal Analysis. ermogravimetric analysis (TGA) and differential thermal analysis (DTA) of Fe3O4 synthesized with Tween-80 surfactant at 30°C are presented in Figure 2. e TGA curve shows a mass loss of the sample whereas the DTA curve indicates the energy gain or loss during the process. e Fe3O4 nanoparticles were thermally stable, and there was no essential weight loss over the entire temperature range in the TG curve (Figure 2)
E total weight loss as shown in TG curve exhibited only 3.726% of weight loss, where the largest portion of this weight loss occurred at the temperature of 25–250°C which could be attributed to the removal of the physically adsorbed water and/or hydroxyl groups on the surface of Fe3O4 nanoparticles. e thermal result implies that the surfactant and cosurfactants were removed through washing from the as-synthesized Fe3O4 NPs and thermal treatment was not necessary for their removal
Summary
Nanoscience and nanotechnologies are attracting the interest of researchers and technologists in several fields for the development of nanoscale materials and devices with new properties and functions. Nanotechnology is the study of manipulating matter on an atomic and molecular scale [1]. Our present environments are filled with various types of pollutants emitted from processes. Nanotechnology is playing an important role in providing effective solutions to the diverse environmental challenges [2]. Nanoparticles are particles between 1 and 100 nanometers (nm) in size with a surrounding interfacial layer [3]. Due to their size, nanoparticles demonstrate unique and controllable properties that are different from the macroscopic scale [4]
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