Hydrothermal Synthesis of Cobalt Doped Magnetite Nanoparticles for Corrosion Protection of Epoxy Coated Reinforced Steel.

Magnetite (Fe³O4) and Cobalt-doped Fe³O4 nanoparticles were obtained by hydrothermal reaction. The synthesized products were characterized by X-ray diffraction, Energy dispersive spectroscopy, Scanning electron microscopy, and Zeta potential. The results show that Co was substituted in the Fe³O4 crystal structure as CoFe2O4 phase. The synthesized materials are nanometer in size having uniform morphology, negatively charged and cobalt concentration varied from 2.5 to 7.5 wt.%. The magnetite and Co-doped magnetite nanoparticles at a low concentration (3 wt.%) were dispersed in the epoxy resin. The effect of the magnetite and Co-doped magnetite nanoparticles on the anticorrosion performance of the protective epoxy coatings covered on carbon steel surface was characterized by Electrochemical Impedance Spectroscopy (EIS) and salt fog exposure. Codoped magnetite nanoparticles at 2.5 wt.% provided high protection of the coatings. In addition, Pull-off tests confirmed an adhesion improvement of the epoxy coating filled by the Co-doped Fe³O4 nanoparticles.

Hg2+-Promoted Spirolactam Hydrolysis Reaction: A Design Strategy for the Highly Selective Sensing of Hg2+ over other Metal Ions in Aqueous Media.

A mercury sensor (N-(rhodamine-6G)lactam-ethylenediamine-4-dimethylamino-cinnamaldehyde-RLED) based on the Hg2+-promoted hydrolysis reaction has been designed and developed with a combination of theoretical calculations and experimental investigations. The interaction between RLED and Hg2+ goes through a fast-initial stage with formation of a 1:1 complex, followed by a slow hydrolysis process. The formation of durable intermediate complexes is due to quite a long hydrolysis reaction time. As a result, RLED can selectively detect Hg2+ in the presence of other metal ions, with a detection limit of 0.08 µM for the colorimetric method, and of 0.008 µM with the fluorescent method. In addition, the RLED sensor can work in a solution with a small amount of organic solvent, with a wide pH range from 5 to 10. The time-dependent density functional theory has been used for investigations of the excitation and de-excitation processes in RLED, intermediate complexes, and reaction products, thereby clarifying the changes in the fluorescence intensity before and after the RLED interacts with Hg2+ ions.

Magnetic NiFe2O4/Exfoliated Graphite as an Efficient Sorbent for Oils and Organic Pollutants.

This study aimed to fabricate, characterize and investigate the applicability of nickel ferrite (NiFe2O4 decorated exfoliated graphite for adsorptive removal of oils and organic compounds. The exfoliated graphite/NiFe2O4 was synthesized via a simple two-step process: (i) exfoliation of the lowcost natural graphite flakes using H2O2 as oxidizing agent and H2SO4 as intercalating agent, (ii) decoration of magnetic NiFe2O4 using the acid citric-based sol-gel process. The synthesized exfoliated graphite/NiFe2O4 hybrid was then applied for the sorption of diesel oil, vegetable oil, gasoline, petroleum ether and tetrahydrofuran. Moreover, the recyclability of the used materials was investigated using either chemical or physical extraction method. Properties of the exfoliated graphite/NiFe2O4 hybrid were analysed using relevant techniques such as Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and Vibrating Sample Magnetometry (VSM) and N2 adsorption/desorption measurement.

Synthesis of BiVO4 Nanoparticles Using Microwave Process and Their Photocatalytic Activity Under Visible Light Irradiation.

A solvothermal method assisted by microwave technique has been developed for the synthesis of highly crystalline and monoclinic BiVO4 powders with ellipsoidal structure, using Bi(NO3)3 · 5H2O and Na3VO4 · 12H2O as raw materials, and oleic acid as surfactant. The phase structure and morphology of as-prepared BiVO4 samples were characterized by XRD, SEM and DRS. We have also investigated the photocatalytic activity of these materials for the decomposition of Rhodamine B under visible light irradiation. From DRS results, BiVO4 samples showed the absorption spectrum up to the visible region and then their photocatalytic activity was shown higher than commercial P-25 TiO2 materials. BiVO4 prepared by the microwave-assisted solvothermal method showed highest photocatalytic activity due to a small particle-size effect.

Photocatalytic Decomposition of Methylene Blue Over MIL-53(Fe) Prepared Using Microwave-Assisted Process Under Visible Light Irradiation.

Iron-based MIL-53 crystals with uniform size were successfully synthesized using a microwave-assisted solvothermal method and characterized by XRD, FE-SEM and DRS. We also investigated the photocatalytic activity of MIL-53(Fe) for the decomposition of methylene blue using H2O2 as an electron acceptor. From XRD and SEM results, the fully crystallized MIL-53(Fe) materials were obtained regardless of preparation method. From DRS results, MIL-53(Fe) samples prepared using microwave-assisted process displayed the absorption spectrum up to the visible region and then they showed the high photocatalytic activity under visible light irradiation. The MIL-53(Fe) catalyst prepared by two times microwave irradiation showed the highest activity.