Nanocarbons including fullerene, carbon nanotube and graphene, known as new carbon allotropes, have the potential to be epoch-making functional materials. Especially, a carbon nanotube, which was discovered by Dr. S. Iijima in 1991, has won the representative position of nanotechnology because of its many attractive physical properties. Since the discovery, 20 years have almost passed. Although carbon nanotube can be applied to a wide variety of products involved in mechanics, electronics, photonics, energy science, biomedical science and so on, it has born less fruit in the practical applications than previously expected, so far. One of the reasons is the difficulty to grow homogeneous nanotubes, especially single-chirality nanotubes. On the other hand, the remarkable progress has been made in separation techniques of single-chirality nanotubes in recent years. The separation techniques would give us the key to solve the problems in its practical applications. In this paper, the brief overview of carbon nanotube basics and hopeful candidates of its applications will be discussed, referring to the other nanocarbons. Then, density gradient ultracentrifugation (DGU) method will be introduced, as one of successful separation techniques, showing our recent results to fabricate carbon nanotube field effect transistors by means of dielectrophoresis with DGU extract solution.
The demand of natural gas is expected to increase because of its environmental superiority. Therefore the importance of the stable supply, reserve and storage is anticipated to increase. Natural gas has been stored in underground reservoir as gas phase or in tanks as liquid phase by now. In this study we proposed the natural gas stockpiling system with natural gas hydrate tank which uses cold energy of LNG plant and executed the computer simulation and the experimental verification of the heat transfer characteristic in the hydrate tank and preservation characteristics in methane hydrate. In the simulation of the heat transfer characteristic, macro heat conduction has increased with the increase of the packing ratio and the adfreezing radius of the NGH pellet. Moreover, it was suggested that the influence by convection be larger than that by the heat transmission between pellets in the tank. In the experiment on the macro thermal conductivity with the ice pellet in random packing, it was suggested that there be a difference of the macro thermal conductivity of about 20% when even the pacing ratio was the same. In the preservation experiment at a temperature of under -80°C (-85°C, -135°C) in methane, hydrate was able to preserve with a low dissociation rate, under 0.1% per day. Finally, it was suggested to have to make the NGH tank at a low price in the approval of the proposed system.
The mechanism for removal of dilute As (V) by coprecipitation with aluminum hydroxide was investigated using sorption isotherms, X-ray diffraction (XRD) patterns, and zeta potential analysis. The results from the coprecipitation experiments were compared with those from simple adsorption experiments. During simple adsorption of As (V) on aluminum hydroxide, the sorption density obeyed a Langmuir-type isotherm. XRD patterns of the adsorbed As (V) were independent of the mass adsorbed. The relationship between zeta potential and sorption density was linear. These results suggest that As (V) was removed mainly by surface complexation. In comparison, during As (V) co-precipitation with aluminum hydroxide, the sorption density followed a BET-type isotherm at pH 5 and 7, and there was a steep increase in sorption density at a transition point. XRD patterns and zeta potential analysis also supported the existence of a transition point during As (V) co-precipitation. The transition was from surface complexation to precipitation, and occurred when the initial molar ratio was As/Al=1.5. These results suggest that during coprecipitation As (V) is removed by surface complexation at molar ratios of As/Al ≤ 1.5, and by the formation of amorphous aluminum arsenate at As/Al ≥ 1.5.
Recently, many kinds of aversive substances (chlorides, alkalies, sulfurs and heavy metals) are brought into cement manufacturing process as raw materials, and they are usually removed by chlorine bypass system from cement kiln-preheater, which is called as "K powder" . Since "K powder" contains not only aversive substances but also cement constituents, its character has been expected to be clarified. In this study, we carried out the analyses on mineralogical and powder properties of "K powder" . As a result, we confirmed that "K powder" was composed mainly of CaO, KCl, CaSO4 and Pb10(SiO4)3(SO4)3Cl2, and its median size was approx. 12 μm, and that "K powder" had a tendency that volatile and heavy metal constituents were concentrated in the size range under 10 μm, and cement constituents were concentrated in 10-44 μm size range. However, volatile and heavy metal constituents were cohesive and adhered to cement constituents, then, it is thought to be difficult to separate specific minerals from each other in the "K powder" by particle size in dry process.
Recently, many kinds of aversive substances (chlorides, alkalies, sulfurs and heavy metals) are brought into cement manufacturing process as raw materials, and they are usually removed by chlorine bypass system from cement kiln-preheater, which is called as "K powder". Since "K powder" still contains cement constituents, its character has been expected to be clarified for the recycling. In this study, we carried out the analyses of "K powder" to identify its minor minerals by various selective dissolution techniques, and created a set of equations estimating the mineral composition of "K powder" from its chemical composition. As a result, we confirmed that K powder was composed from 19 or more minor minerals such as SiO2, 2CaO·SiO2, 2CaO·Al2O3·SiO2, 2CaO·(Al, Fe)2O3, Ca3(SO3)2SO4, CaS, KCl·2PbCl2, CaMg(CO3)2 and K3Na(SO4)2, etc., and created a set of equations by norative calculation assuming that "K powder" is composed from typical 12 minerals such as Na2SO4, K2SO4, KCl, CaSO4, CaO, SiO2, 2CaO·SiO2, 2CaO·Al2O3·SiO2, 2CaO·Fe2O3, CaMg(CO3)2, Pb10(SiO4)3(SO4)3Cl2 and KCl·2PbCl2. The result set of equations was found to correspond with the measured values of free lime and residual solid contents determined by water washing treatment. Then, the estimating method could be demonstrated a good tool to identify the mineral composition of "K powder".
The formation process of Co, Ni, Co-Ni alloy nanoparticles by electroless deposition in nonaqueous solution (ethylene glycol: EG) was electrochemically investigated. When the solvent decomposes during the cathodic reduction of relatively-less noble metals (Co, Ni, Fe, etc.) , the reduction current of the metals is hardly measured from the total current by the voltammetry because of the large contribution of the decomposition of the solvent. In this work, the deposition current of Co and Ni was evaluated from a weight change due to the metal deposition on a quartz crystal microbalance electrode. The deposition current of Co on a Co substrate was much higher than that of Ni on a Ni substrate, and the oxidation current of a reducing agent (hydrazine monohydrate) on Co is also higher than on Ni. This resulted in a decrease of Co-Ni nanoparticle size by the addition of Ni.