Abstract
This work is devoted to the study of magnetic Fe3O4 nanoparticles doubly coated with carbon. First, Fe3O4@C nanoparticles were synthesized by thermal decomposition. Then these synthesized nanoparticles, 20–30 nm in size were processed in a solution of glucose at 200 °C during 12 h. The morphology and features of the magnetic properties of the obtained hybrid nanoparticles were characterized by transmission electron microscopy, differential thermo-gravimetric analysis, vibrating sample magnetometer, magnetic circular dichroism and Mössbauer spectroscopy. It was shown that the magnetic core of Fe3O4@C nanoparticles was nano-crystalline, corresponding to the Fe3O4 phase. The Fe3O4@C@C nanoparticles presumably contain Fe3O4 phase (80%) with admixture of maghemite (20%), the thickness of the carbon shell in the first case was of about 2–4 nm. The formation of very large nanoparticle conglomerates with a linear size up to 300 nm and of the same regular shape is a remarkable peculiarity of the Fe3O4@C@C nanoparticles. Adsorption of organic dyes from water by the studied nanoparticles was also studied. The best candidates for the removal of dyes were Fe3O4@C@C nanoparticles. The kinetic data showed that the adsorption processes were associated with the pseudo-second order mechanism for cationic dye methylene blue (MB) and anionic dye Congo red (CR). The equilibrium data were more consistent with the Langmuir isotherm and were perfectly described by the Langmuir–Freundlich model.
Highlights
Magnetic nanoparticles (NPs) remain a hot trend in condensed matter physics despite the relatively long history of their research, primarily due to the many new questions that they pose for fundamental science and their applications in various modern technologies.A large number of synthesis methods leads to a large variety of NPs properties
The powder X-ray diffraction (XRD) patterns are shown by curves 1 in Figure 2a,b for the initial Fe3 O4 @C@C sample included 80% magnetite (Fe3 O4) @C NPs and for the double carbon coated Fe3 O4 @C@C NPs, correspondingly
The calculated values of qe (Table 2) determined by the pseudosecond order model are more consistent with the measured values of qe. These results prove that the adsorption process of these dyes on Fe3 O4 @C@C NPs followed the pseudo-second order kinetic model, suggesting that adsorption is dependent on the amount of the solute adsorbed on the surface of the adsorbent and the number of active sites
Summary
Magnetic nanoparticles (NPs) remain a hot trend in condensed matter physics despite the relatively long history of their research, primarily due to the many new questions that they pose for fundamental science and their applications in various modern technologies.A large number of synthesis methods leads to a large variety of NPs properties. Magnetic nanoparticles (NPs) remain a hot trend in condensed matter physics despite the relatively long history of their research, primarily due to the many new questions that they pose for fundamental science and their applications in various modern technologies. NPs tend to agglomerate in order to reduce their surface energy and modification of the NPs surface is a solution to prevent this phenomenon. Surface modification can be accomplished by physical and/or chemical adsorption of the desired molecules to coat the surface. Carbon shell is one of the universal coatings for NPs, which is used in many cases. It provides exceptional chemical stability and protects the magnetic core from oxidation, allowing further functionalization of the carbon surface.
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