Carbon Double Coated Fe(3)O(4)@C@C Nanoparticles: Morphology Features, Magnetic Properties, Dye Adsorption

This work is devoted to the study of magnetic Fe(3)O(4) nanoparticles doubly coated with carbon. First, Fe(3)O(4)@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 Fe(3)O(4)@C nanoparticles was nano-crystalline, corresponding to the Fe(3)O(4) phase. The Fe(3)O(4)@C@C nanoparticles presumably contain Fe(3)O(4) 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 Fe(3)O(4)@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 Fe(3)O(4)@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.