Abstract: In this work, we report a simple and advanced approach to fabricate graphene nanoplatelets (GNPs) in the industrial scale. In this method, GNPs is obtained from the natural graphite in a single step of exfoliation with sulphuric acid 100% and oxidizing agents. The morphology and properties of GNPs is characterized by using SEM, EDS, XRD, and TEM. The resultant GNPs are 10-20μm in diameter, 5-15nm in thickness, and the bulk density of 0.015 g ml-1.
Abstract: This paper describes the modification of ultralight flexible carbon foam by chemical vapor deposition (CVD) of silicon carbide whiskers (SiCw). The effect of SiC whiskers on the microstructure and the thermal conductivity of carbon foam were investigated by scanning electron microscopy (SEM) and laser flash diffusivity method in a Netzsch LFA427. The results show that the macro-pores (~30 μm) of the carbon foam were divided by the random distribution of SiC whiskers. The diameter of SiC whiskers decreased with decreasing catalyst concentration which resulted in the improved microstructure with a smaller pore diameter (4~6 μm) and a more homogeneous distribution of the pores. The carbon foam reinforced by SiCw exhibits better insulation performance than the pristine carbon foam when the temperature exceeds 200°C.
Abstract: In this work, graphene oxide (GO) is synthesized via chemical method (improved method) and reduced graphene oxide (rGO) using thermal treatment. The GO and rGO thin films were coated on a glass substrate by using drop casting method. The GO and rGO thin film were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) to make sure the morphological and optical characteristics of the thin film. In addition, the electrical studies were performed by current-voltage (I-V) characteristic. The rGO thin film displays higher conductivity in comparison with GO which is 4.12 x 10-5 S/cm, and also affected the morphological (SEM) and optical properties (FTIR). Morphological and optical data confirms that rGO losses the oxygen groups compare to GO.
Abstract: The Electrical properties of polyurethane (PU) filled with graphene nanosheets (GRN) at low frequency is investigated. In last decade, polyurethane elastomers have attracted attention in transducer and actuator applications. The dielectric constant is one of the key factors for increasing actuator ability. Graphene nanosheets as conducting fillers have to be filled to increase the dielectric constant. In order to prove this idea, polyurethane composites with various graphene contents have been characterized by SEM and DSC. And their electrical capability has been measured at various frequencies of 101-104 by using LCR meter. To gain the films, polyurethane composites filled with various graphene contents were prepared by solution casting method. The results showed a well homogenous dispersion of the graphene filler in the polyurethane matrix. In addition, it was found that the glass transition temperature (Tg) of the PU/GRN increase as the content of filler increased and it can be affected the interfacial polarization between PU matrix with the GRN fillers. Therefore, it is found that graphene in the polyurethane matrix exhibit high enhanced the electrical properties and the optimal dielectric constant at 2wt% graphene of 9.74.
Abstract: The way to produce the nanostructured carbon filaments via H2-assisted catalytic decomposition of CF2Cl2 over self-organizing Ni-based catalyst has been reported. The self-organizing 6%Ni/CNM catalyst, where CNM is a carbon nanomaterial, resulted from carbon erosion of bulk Ni-Cr alloy (nichrome) in C2H4Cl2 vapors was also shown to be effective for catalytic chemical vapor deposition of CF2Cl2 with formation of bimodal carbon structures. It was demonstrated that interaction of nichrome with CF2Cl2/H2 reaction mixture at 600 °C leads to its rapid disintegration caused by carbon erosion to form disperse active Ni-particles catalyzing the growth of carbon filaments. The resulted filamentous carbon material is characterized with high textural parameters.
Abstract: Nitrate removal or denitrification, involves reduction of nitrate into nitrogen and oxygen. The use of nanoparticles zero valent metals for denitrification receives great attention as they have been proven to be effective and environmentally safe. In this work, the nanoparticles were prepared by reducing the metals salts, dissolved in a mixed solution of water and ethanol, using sodium borohydrate. The nitrate reduction reaction took place in an ambient environment – room temperature, neutral pH and aerobic condition. Results from the experiments carried out showed that nitrate has been successfully reduced up to a maximum of 40% in all the samples without an increase in the pH of the solution, a strong indication that ammonia was not produced. As for the study on the reactivity of the recycled NZVI, the samples synthesized with 4:1 (v/v) ethanol/water and using 9: 1 (v/v) ethanol/water, the reactivity of the iron is similar to the fresh NZVI for the first two hours of the study.
Abstract: In this paper, we demonstrated an artificial nanoparticles, Laponite, as a high performance rheological modifier in water-based drilling fluids. We made a comparison between Laponite nanoparticle and bentonite as rheological modifier in polyanionic cellulose (PAC) solution and weitghted water-based drilling fluids. In viscosity-shear rate test, both Laponite and bentonite could translate 0.5 wt.% PAC solution from Newton fluids to yield-pseudoplastic fluid. However, 1 wt.% Laponite was better in improving the shear-thinning behavior compared with 4 wt.% bentonite. In the stress-shear rate test, the results were fit with Bingham model with a high R2, and 1 wt.% Laponite/0.5 wt.% PAC suspension had a yield point of 5.19 Pa, which was higher than that of 4 wt.% bentonite/0.5 wt.% PAC suspension (3.13 Pa). Similarly, 1 wt.% Laponite/0.5 wt.% PAC suspension maintained a G’ of 12 Pa in the oscillation frequency sweep test, whereas G’ of 4%bentonite/0.5%PAC suspension was nearly 5 Pa. Particularly, 0.5 wt.% PAC /Laponite suspensions could maintain higher gel structure, yield point and better shear-thinning behaviors after 120°C hot rolling. The TEM image revealed that nanoscaled Laponite could form a “star network” with PAC in water, which explained the good rheological properties of PAC/LAP mixed suspensions. Besides, in the weighted drilling fluids, 1 wt.% Laponite could maintained a much higher gel strength compared with 4 wt.% bentonite.As the unique rheological properties, Laponite nanoparticles can greatly enhance abilities of water-based drilling fluids in circulating cuttings and making the borehole clean.
Abstract: In this paper, the researcher synthesis a super-hydrophobic nanosilica to alter the wettability of the sandstone surface from hydrophilic to super-hydrophobic. Fourier transform infrared (FTIR), Thermogravimetric analysis (TGA), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were used to test the characterization of the products, and the wettability were examined by contact angle measurement, glass capillary tube rise measurement and spontaneous imbibition tests. The results shows that the water contact angle is over 150°,the liquid level is down to-42mm and the spontaneous volume is only 0.025mL after the surface modified with super-hydrophobic nanosilica which means the surface wettability is altered to be super-hydrophobic.
Abstract: Recently, interest in plant-mediated synthesis of the silver nanoparticles (AgNPs) is growing among researchers and till now the potential of different plants is still further explored to synthesize nanoparticles. Conventionally, AgNPs are synthesized using chemical and physical methods. However, these methods involve use of toxic and hazardous chemicals which are harmful to health and environment. Therefore, plant-mediated synthesis has been used as environmental friendly alternative to overcome the limitation of conventional methods. The bioactive compounds in plant acts as natural reducing and stabilizing agents which help to increase the rate of synthesis and stabilization of synthesized nanoparticles. Besides, the nanoparticles synthesized using plants are reported to be more stable and the rate of synthesis is much faster compared to other methods. This review focuses on the biosynthesis of AgNPs using plant as natural source plant and the effect of reaction conditions are summarised and discussed.
Abstract: In present work, a new technique to prepare alumina nanoparticles and nanofibers using a sol-gel method was proposed. A solution combustion method was applied to form a nanostructured catalytically active layer of CuO–Co3O4–CeO2 on the surface of the alumina. The uniform distribution and fine dispersion of active components provide the appropriate activity of the catalysts obtained in a model reaction of CO oxidation. The morphology of nanostructured alumina was found to affect the catalytic behavior. Carbon monoxide conversion was observed at lower temperatures when alumina nanofibers were used as a catalyst support.