Oil pollution in the ocean is becoming more and more of a serious issue, which increases interest in both ways for combating its cause and methods for observing and monitoring how oil spreads. A promising approach based on an optical method with empirical relations for selected viscous oil-water systems is presented. Based on a modified melamine sponge (MMS), the microscopic spreading and oil capillary penetration phenomenon of the porous structure were investigated.
View Article and Find Full Text PDFIn this study, we demonstrate an integrated synthesis strategy, which is conducted by the thermochemical process, consisting of pre- and post-activation by thermal treatment and KOH activation for the reduction of graphite oxide. A large number of interconnected pore networks with a micro/mesoporous range were constructed on a framework of graphene layers with a specific surface area of up to 1261 m g. This suggests a synergistic effect of thermally exfoliated graphene oxide (TEGO) on the removal efficiency of volatile organic compounds by generating pore texture with aromatic adsorbates such as benzene, toluene, and -xylene (denoted as BTX) from an inert gaseous stream concentration of 100 ppm.
View Article and Find Full Text PDFCurrently, researchers are paying much attention to the development of effective 3D graphene for applications in energy storage and environmental purification. Before commercialization, however, it is necessary to develop a method that allows for the large-scale production of such materials and enables good control over their structural and chemical properties. With this objective, we herein developed a simple method for the formation of large-scale (4 in.
View Article and Find Full Text PDFDuring nearly 2 centuries of history in graphene researches, numerous researches were reported to synthesize graphene oxide (GO) and build a proper graphene assembly. However, tons of research prevail without verifying the reproducibility of GO that can be sensitively attributed by the graphite nature, and chemical processes. Here, the structure and chemistry of GO products were analyzed by considering parent graphite sources, and three different oxidation methods based on Hummer's method and the addition of HPO.
View Article and Find Full Text PDFClosed-box loudspeaker systems (CBLSSs) are compact and simple air-suspension loudspeaker systems, and their low-frequency responses are determined by two fundamental parameters: resonance frequency and total damping. Recently, electronic devices have come to require more compact designs, so the volumes of loudspeaker should be reduced. However, a small loudspeaker cannot retain sufficient acoustic space, resulting in poor low-frequency acoustic performance.
View Article and Find Full Text PDFThe most crucial step towards conducting experimental studies on thermophysical properties and heat transfer of nanofluids is, undoubtedly, the preparation step. It is known that good dispersion of nanoparticles into the base fluids leads to having long-time stable nanofluids, which result in having higher thermal conductivity enhancement and lower viscosity increase. Ultrasonic treatment is one of the most effective techniques to break down the large clusters of nanoparticles into the smaller clusters or even individual nanoparticles.
View Article and Find Full Text PDFAs novel technologies have been developed, emissions of gases of volatile organic compounds (VOCs) have increased. These affect human health and are destructive to the environment, contributing to global warming. Hence, regulations on the use of volatile organic compounds have been strengthened.
View Article and Find Full Text PDFVolatile organic compound (VOC) gases can cause harm to the human body with exposure over the long term even at very low concentrations (ppmv levels); thus, effective absorbents for VOC gas removal are an important issue. In this study, accordingly, graphene-based adsorbents with microsized pores were used as adsorbents to remove toluene and acetaldehyde gases at low concentrations (30ppm). Sufficient amounts of the adsorbents were prepared for use on filters and were loaded uniformly at 0.
View Article and Find Full Text PDFCondensed liquid behavior on hydrophobic micro/nano-structured surfaces is a subject with multiple practical applications, but remains poorly understood. In particular, the loss of superhydrophobicity of hydrophobic micro/nanostructures during condensation, even when the same surface shows water-repellant characteristics when exposed to air, requires intensive investigation to improve and apply our understanding of the fundamental physics of condensation. Here, we postulate the criterion required for condensation to form from inside the surface structures by examining the grand potentials of a condensation system, including the properties of the condensed liquid and the conditions required for condensation.
View Article and Find Full Text PDFFor several decades, evaporation phenomena have been intensively investigated for a broad range of applications. However, the dynamics of contact line depinning during droplet evaporation has only been inductively inferred on the basis of experimental data and remains unclear. This study focuses on the dynamics of contact line depinning during droplet evaporation based on thermodynamics.
View Article and Find Full Text PDFBoiling heat transfer (BHT) is a particularly efficient heat transport method because of the latent heat associated with the process. However, the efficiency of BHT decreases significantly with increasing wall temperature when the critical heat flux (CHF) is reached. Graphene has received much recent research attention for applications in thermal engineering due to its large thermal conductivity.
View Article and Find Full Text PDFWe report a novel boiling heat transfer (NBHT) in reduced graphene oxide (RGO) suspended in water (RGO colloid) near critical heat flux (CHF), which is traditionally the dangerous limitation of nucleate boiling heat transfer because of heater failure. When the heat flux reaches the maximum value (CHF) in RGO colloid pool boiling, the wall temperature increases gradually and slowly with an almost constant heat flux, contrary to the rapid wall temperature increase found during water pool boiling. The gained time by NBHT would provide the safer margin of the heat transfer and the amazing impact on the thermal system as the first report of graphene application.
View Article and Find Full Text PDFSelf-assembled foam-like graphene (SFG) structures were formed using a simple nucleate boiling method, which is governed by the dynamics of bubble generation and departure in the graphene colloid solution. The conductivity and sheet resistance of the calcined (400°C) SFG film were 11.8 S·cm(-1) and 91.
View Article and Find Full Text PDFRecently, there has been intensive research on the use of nanotechnology to improve the wettability of solid surfaces. It is well-known that nanostructures can improve the wettability of a surface, and this is a very important safety consideration in regard to the occurrence of boiling crises during two-phase heat transfer, especially in the operation of nuclear power plant systems. Accordingly, there is considerable interest in wetting phenomena on nanostructures in the field of nuclear heat transfer.
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