N. Balasubramanian

α-Fe2O3/reduced graphene oxide nanorod as efficient photocatalyst for methylene blue degradation

Abstract A series of α-Fe2O3/reduced graphene oxide (RGO) nanorod composites were successfully synthesised using a simple solvothermal process. The synthesised α-Fe2O3/RGO (FG) products were characterised by X-ray diffraction (XRD), UV diffuse reflectance spectra (DRS), Raman spectroscopy, energy dispersive spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS) techniques. The photocatalytic ability of the prepared FG composites was evaluated, by the demineralisation of methylene blue (MB) in an aqueous solution under visible light irradiation. The synthesised FG composites show higher degradation efficiency under visible light irradiation with improved photocatalytic performance than the pure α-Fe2O3 nanorod and degusa P25. The demineralisation of the dyes was visualised by a UV-visible spectroscopy, by decrease in the intensity of absorbance and concentration. The degradation efficiency of the FG1 composite towards MB was found to be 97%.

Visible light photocatalysis of Methylene blue by graphene-based ZnO and Ag/AgCl nanocomposites

The present investigation deals with the photocatalytic activity of two different graphene oxide-(GO) based nanocomposites i.e. Ag/AgCl/GO and ZnO/GO for the degradation of Methylene blue (MB). The composites were prepared by low-temperature hydrothermal method and were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD), and Raman spectroscopy. SEM analysis showed that GO was stacked between the hexagonal ZnO nanostructures and in the case of Ag/AgCl, it was grafted onto the distorted spheres of Ag/AgCl. This distorted structure may be due to the overloading of the silver precursor close to the saturation during the synthesis. XRD pattern confirms the formation of both the nanocomposites. Both the nanocomposites showed good performance in degrading the dye under sunlight. ZnO/GO being a semiconductor photocatalyst showed 95% removal of dye in 100 min, whereas plasmonic catalyst Ag/AgCl/GO was found to degrade 92% of MB within 50 min of reaction time due to its unique surface plasmon resonance property. Raman spectroscopy confirms the enhanced photocatalytic activity of both the nanocomposites, which is due to the electron-accepting property of the GO and hinders the recombination of electron‐hole pair.

Equilibrium, kinetic and thermodynamic studies for the removal of Zn(II) and Ni(II) ions using magnetically recoverable graphene/Fe3O4 composite

AbstractMagnetically recoverable graphene/Fe3O4 composite (GFC) was synthesized using a one-step solvothermal method by the simultaneous reduction of graphene oxide (GO) to graphene and FeCl3·6H2O to Fe3O4, in the presence of ethylene glycol and sodium acetate. The synthesized GFC adsorbent was characterized using FTIR, Raman, X-ray powder diffraction analysis, scanning electron microscopy, energy dispersive analysis of X-ray, thermo gravimetric analysis and vibrating sample magnetometer. The adsorption of Zn(II) and Ni(II) ions onto GFC has been investigated using batch adsorption studies. The adsorption experiments were carried out to examine the influence of parameters such as pH, GFC dosage, initial metal ion concentration, temperature and contact time. The adsorption isotherm data were fitted in the order of Langmuirxa0>xa0Redlich–Petersonxa0>xa0Temkinxa0>xa0Freundlich, based on the correlation coefficient values. From the Langmuir isotherm model, the maximum adsorption capacity of the GFC adsorbent towards Zn(I...