Adsorption behavior and mechanism of As(V) on magnetic Fe3O4-graphene oxide (GO) nanohybrid composite material.

In this study, the magnetic Fe3O4-graphene oxide (GO) nanohybrid composite material was prepared via the combination of the modified Hummer's method and coprecipitation. The morphology of the hybrid sample showed that the diffusion of Fe3O4 nanoparticles into the porous channels of mesoporous GO layers not only restricted the restacking of GO nanosheets but also prevented the leaching and agglomeration of magnetic nanoparticles. The result of the kinetic and isotherm studies that were performed to evaluate the adsorption mechanism showed a good fit with the pseudo-second-order kinetic and Langmuir isotherm models. The As(V) adsorption efficiency, H, of the GO/Fe3O4 nanohybrid composite material reached the maximum value of 99.37% after 60 min. The maximum adsorption capacity qm of the GO/Fe3O4 nanohybrid material was 14.1 mg·g-1 in an acidic aqueous solution (pH 1). The role and contribution of GO and Fe3O4 nanoparticles in adsorption and the improvement in As(V) adsorption efficiency were also investigated in further detail. The findings of this work suggested that the GO/Fe3O4 nanohybrid material could be widely applied for polluted water treatment.

Structural and H2S Sensing Properties of Copper Ferrite Nanoparticles Prepared Through Hydrothermal Method.

In this paper, we report the H2S sensing properties of partially inverse copper ferrite (CuFe2O4) nanoparticles with sizes ranging from 16 nm to few hundreds of nanometers prepared through hydrothermal method. Effects of annealing temperature on the particle size, microstructure and gas-sensing properties of spinel ferrite were studied through scanning electron microscopy, synchrotron X-ray powder diffraction and resistance measurement. Electrical conduction mechanism is discussed based on the cation distribution in the lattice and resistance contribution from the grain boundaries. Gas sensing ability of the samples was recognized for H2S concentrations from 5 down to 0.5 ppm and in working temperature range from 50 to 250 °C.