Synthesis of fe/ni bimetallic nanoparticles and application to the catalytic removal of nitrates from water

This work investigated the effectiveness of zerovalent iron and Fe/Ni bimetallic nanoparticles in the treatment of water polluted by a high concentration of nitrates. Nanoparticle synthesis was carried out by a sodium borohydride reduction method in the presence of sodium oleate as a surfactant. The particles were characterized by XRD and SEM. Batch experiments were conducted on water samples contaminated by 300 mg L−1 of nitrate. The parameters investigated were the Fe/Ni dosage (0.05, 0.1, 0.2, 0.3, and 0.4 g L−1) and the reaction pH (unbuffered; buffered at pH = 3; initial pH = 3, 5, and 10). The results showed that almost complete nitrate removal (>99.8%) was always achieved after 15 min at a concentration of bimetallic nanoparticles higher than 0.2 g L−1 . The optimization of bimetallic nanoparticle dosage was carried out at a fixed pH. Kinetic study tests were then performed at different temperatures to assess the effect of temperature on the nitrate removal rate. By fixing the pH at acidic values and with an operating temperature of 303 K, nitrates were completely removed after 1 min of treatment

Structure and thermal properties of copper-polypropylene based nanocomposites

Polymer nanocomposites based on PP/Cu were obtained by the combining of ex-situ casting solution and hot pressing methods. The structure of polymer nanocomposites was characterized by XRD, SEM, EDS, AFM and FT-IR spectroscopy analysis. The thermal properties were analyzed using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was found that the addition of copper nanoparticles to the PP polymer matrix increases the thermal stability of the polymer, and this thermal stability reaches its maximum value at 3% content of copper nanoparticles in the polymer. The reason for the increase in the thermal properties of nanocomposites is associated with the formation of a more perfect, dense and ordered structure of PP-based composites and the fact that nanoparticles play the role of a nucleus of crystallization for polymer matrices

Correction to: Influence of magnetite nanoparticles on the dielectric properties of metal oxide/polymer nanocomposites based on polypropylene (Russian Physics Journal, (2018), 60, 9, (1572-1576), 10.1007/s11182-018-1253-5)

The name of the first author should read A. М. Maharramov

The effect of the temperature-time mode of crystallization on the morphology and thermal properties of nanocomposites based on polypropylene and magnetite (Fe3O4)

In the present study, the influence of the temperature–time mode of crystallization (TTC) on the morphology and thermal properties of PP/Fe3O4 nanocomposite materials was investigated. The morphology of the nanocomposites prepared in different TTC mode was studied by atomic force microscope. AFM study shows that the root mean square roughness of samples is 90–95, 50, 21 nm for PP/Fe3O4@20, PP/Fe3O4@200 and PP/Fe3O4@20000 respectively. Thermo gravimetric analysis was employed to investigate the thermal stability of PP/Fe3O4 nanocomposites obtained applying different TTC modes. It was found that thermal stability of water-cooled nanocomposite samples (PP/Fe3O4@200) is higher than the thermal stability of samples obtained with other two modes. Crystallization and melting behaviors of nanocomposite samples prepared in different TTC mode have been studied with DSC method and the degree of crystallinity of samples was calculated. It was found that, degree of crystalization decreases with increasing of cooling rate. The XRD patterns of samples produced in different TTC modes also correlate well with this result

Influence of magnetite nanoparticles on the dielectric properties of metal oxide/polymer nanocomposites based on polypropylene

Structure and dielectric properties of polymer nanocomposites based on isotactic polypropylene and iron oxide (Fe3O4) nanoparticles are studied. Distribution of magnetite nanoparticles in a polymer matrix was studied by scanning electron microscopy (SEM, Carl Zeiss). Dielectric properties of nanocomposites were examined by means of E7-21 impedance spectrometer in the frequency range of 102–106 Hz and temperature interval of 298–433 K. The frequency and temperature dependences of the dielectric permittivity ε, as well as the temperature dependence of log (ρ) were constructed. It is shown that introduction of the magnetite (Fe3O4) nanoparticles into a polypropylene matrix increases the dielectric permittivity of nanocomposites. An increase in the dielectric permittivity is explained by the increase in the polarization ability of nanocomposites. It is found that a decrease in the specific resistance with increasing temperature up to 318 K is associated with an increase in the ionic conductivity of nanocomposites. An increase in the resistance at temperatures higher than 358 K is due to the destruction of the crystalline phase of the polymer, as a result of which the distance between the Fe3O4 nanoparticles increases

Negative magnetoresistance of polymer nanocomposites on the basis of PP + Fe3O4 and PVDF + Fe3O4 in the magnetic field

In the present study, we report about the influence of an external permanent magnetic field on electrical resistivity and dielectric permittivity of PP + Fe3O4 and PVDF + Fe3O4 based nanocomposites. It was found that independent of the type of polymer the electric resistivity of both polymer nanocomposites decreases under the influence of a magnetic field and the negative magnitoresistive effect has been observed. Investigation of MR in PP + Fe3O4 and PVDF + Fe3O4 based nanocomposites showed that at room temperature the concentration dependence of MR is identical for both systems. However, the electrical resistance of the PVDF + Fe3O4 based nanocomposite was found to reduce strongly in comparison with that of the nanocomposite based on PP + Fe3O4 under the influence of a magnetic field. This could be explained by the fact that the diamagnetic anisotropy and the charge carriers’ density of these polymers are quite different from each other. Negative magnetoresistance of composite films with ferromagnetic nanoparticles incorporated in dielectric matrix is due to the tunneling transitions of electrons between neighboring nanoparticles. Decrease in dielectric permittivity under a magnetic field is consistent with negative magnetoresistive effect