The diffusion coefficients of cetyl alcohol in supercritical carbon dioxide were measured by the pseudo steady state solid dissolution method at 308.2 K. The Schmidt number correlation was applied to correlate with the experimental diffusion coefficients. Further, molecular dynamics simulation was performed to calculate the diffusion coefficients by an all atom model of solute. The correlated results by the Schmidt number correlation show good agreement with the experimental results. The calculated results by molecular dynamics simulation give fair estimation to the experimental data without adjustable parameters.
Liquid molar volumes of typical alcohols and hydrocarbons measured previously under atmospheric pressure at 20–70°C are complied and tabulated. An additive method by Elbro et al. was adopted to predict these liquid molar volumes. The method is found to be useful. However, it cannot be adopted to several substances because additive factors required are not available. In this study, a simple predictive method is proposed by using the expansion coefficient, β = (vb – v25)/(tb – t25). The molar volumes at 25°C, v25, and at the normal boiling point, vb, were predicted by the additive methods of Fedors and Le Bas, respectively. Liquid molar volumes at the temperature t can be predicted by v25 + β(t – 25). The present approach is found to be successful except for small molecules, such as methanol and ethanol.
The gas liquid mass transfer volumetric coefficients KLa in several kinds of small size shaking flasks were measured with an optical method based on sulfite oxidation without oxygen concentration probe and liquid sampling. It was found that the liquid film on the inner surface of a flask was one of the very important factors to increase KLa. The baffled flask was effective to obtain a larger oxygen transfer rate than the normal flask. A new developed baffled cylindrical vessel based on the baffled small flask has about three times larger KLa than the normal vessel.
The effect of initial bubble conditions on the motion of a gas bubble rising in viscous liquids was investigated by 3D-computations. Then, a coupled level set/volume-of-fluid (CLSVOF) method was used as a numerical method. For high Eötvös and very low Morton numbers regions predicting a 3D “spherical-cap” bubble, it was computationally demonstrated that the resulting final state of bubbles depended on initial bubble conditions; bubbles with break-up at the center or “spherical-cap” bubbles depending on initial bubble conditions were reproduced. On the other hand, we showed for low Eo and high M conditions that initial bubble conditions did not affect the terminal state of bubble rising motion.
In order to find the optimum limestone addition rate for the desulfurization during fluidized bed sludge incineration, a simulation is conducted using a thermodynamic equilibrium model. For the analyses of the desulfurization and the pollutant emissions by the limestone addition, the Ca/S molar ratio is changed up to 7.0 with the consideration of the CaO bound in the ash of the sludge. According to the simulation, it is found that the desulfurizing reaction with limestone is greatly influenced by phosphorous content in the ash. If the Ca/P molar ratio is less than two, the desulfurizing reaction between CaO and S may not occur. The reason is that the reactivity of CaO with a P component in the ash is superior to that with an S component.
A crosslinked N-methylene phosphonic chitosan (=NMPC) was newly synthesized by reacting chitosan with phosphorous acid in order to remove traces of copper(II) from a crude palladium(II) solution. First of all, the adsorption selectivity of NMPC for metal ions was examined from a 1 mol/dm3 (=M) aqueous ammonium nitrate solution. The adsorption of metal ions on NMPC was dependent on an equilibrium pH, and their adsorption shifted to a lower pH region compared with crosslinked original chitosan (=CLC). NMPC began to adsorb all the metal ions except for palladium(II) at around pH 1–3 and then their adsorption increased with an increase in pH. On the contrary, palladium(II) was adsorbed in lower pH around 0–1, then its adsorption rapidly decreased with increasing pH. These results indicate that base metals can be selectively separated and removed from the crude palladium(II) solution using NMPC only by adjusting the pH. Especially, the adsorption equilibrium of copper(II) was quantitatively examined since the separation of copper(II) from a crude palladium(II) solution is commercially very important. The adsorption of copper(II) showed the maximum value at around pH 5 and then it rapidly decreased in the higher pH region. The adsorption of copper(II) was little dependent on the ammonium nitrate concentration at pH < 4, however, beyond which it decreased with the increasing concentration of ammonium nitrate. The adsorption equilibrium of copper(II) was quantitatively discussed by taking account of the formation of ammine complexes of copper(II) with ammonia in the higher pH region. The adsorption capacity of NMPC for copper(II) was 3.81 mol/kg, which is twofold greater than that of CLC.
The separation of protein in a cross-flow microfiltration of microbe/protein binary suspension is studied. The yeast cells and albumin bovine serum (BSA) are served as typical samples for preparing binary suspensions. Effects of cross-flow velocity and filtration pressure on the cake properties, the filtration flux and the BSA rejection are discussed. An increase in cross-flow velocity leads to a more compact cake with a higher specific filtration resistance; however, the thinner cake thickness results in a higher filtration flux. On the other hand, the cake thickness, the filtration resistance as well as the filtration flux increase with the increase of filtration pressure. The filter cake plays a major role on the BSA rejection. An increase in cross-flow velocity or filtration pressure causes the observed BSA rejection to become higher. A theoretical model based on the resistance-in-series model, the force balance model for particle deposition, the concentration polarization model and the standard capture equation for depth filtration is derived for predicting the filtration flux and the observed BSA rejection directly from operating conditions. The agreements between calculated results and experimental data demonstrate the reliability of the proposed model. The optimum operating condition for highest BSA separation efficiency is also suggested.
Porous silica membranes were tested for the separation performance by vapor permeation and pervaporation of acetic acid/water mixtures at normal boiling points. Because of the small membrane thickness of about 0.5–1 μm the membrane showed a large water flux of about 400 mol·m–2·h–1 (7.2 kg·m–2·h–1) with a separation factor of 500 for pervaporation at 73 mol% (90 wt%) of acetic acid, while a smaller flux of about 200 mol·m–2·h–1 (3.6 kg·m–2·h–1) with a separation factor of about 200 was observed for vapor permeation at the same feed concentration. The smaller water flux for vapor permeation is because of the condensation of the feed mixture on the membrane surface due to the concentration polarization in the vicinity of the membrane surface, causing a temperature rise at the membrane surface due to the heat of condensation. The temperature rise was observed clearly during the vapor permeation tests, and the heat and mass transfer mechanisms are qualitatively discussed.
Ni-doped silica membranes of various Ni contents (Si/Ni = 0–1/1) were prepared on porous SiO2–ZrO2 composite intermediate layers (Si/Zr = 1/1) by the sol-gel techniques to test their hydrothermal stability and gas permeation characteristics in steam at high temperatures (steam: 90–400 kPa, 500°C). Preceding firing of the intermediate layer and the Ni-doped silica layer in steam at higher temperatures (steam: 90 kPa, 650°C) before exposed to hydrogen at high temperatures was found to drastically improve the hydrothermal stability of Ni-doped silica membranes in steam, showing, for example, a steady permeance of He around 1.7 × 10–5 [m3(STP)·m–2·s–1·kPa–1] with high selectivity of 1150 (He/N2) in steam (steam: 90 kPa, 500°C), which did not change largely even in steam of higher pressure (steam: 400 kPa, 500°C). It was also found that the membrane selectivity could be further improved with negligible decrease in H2-permeance by firing the membranes after impregnating dilute aqueous NiNO3 solution.
We fabricated a scaffold of poly (lactic acid) and acidic gelatin, a sustained-release carrier of basic fibroblast growth factor (bFGF), which is a positive regulator of angiogenesis. After 1 week of implantation into mesentery of rats, blood vessels induced in the bFGF-containing scaffolds were almost double those in the bFGF-free scaffolds. Further, histological examination of hepatocyte-immobilizing scaffolds retrieved after 1 week of implantation into the mesentery of the rats that received a 70% hepatectomy revealed that the bFGF-containing scaffolds were more efficient for immobilized cell survival than the bFGF-free scaffolds. As well, hepatocytes in the bFGF-containing scaffolds kept their hepatospecific glycogen storage capacity.
We have investigated that a droplet-based microreactor system, such as Lab-on-a-chip, especially for using no mechanical pump. In this paper, a method to produce water droplets in oil electrically was experimented. Electrostatic atomization was studied to inject charged water droplets into oil in a microchannel system. When a negative DC voltage (–7 kV) was applied to Milli-Q water phase of microchannel, Taylor cone was formed at an interface between the water and rapeseed oil, and the water droplets were injected into oil. A diameter of the produced droplets was characterized to 10.7 ± 3.8 μm. When Milli-Q water replaced to 50% glycerol that was 6 times higher viscous liquid, the produced droplets were with 6.7 ± 2 μm. Since the electrostatic atomization, in principle, produces charged droplets into oil, the produced droplets will be manipulated using electric force.
An Al dual damascene process for the metallization of sub-100 nm dynamic random access memory devices was performed, and the effects of wafer cleaning method on the damascene structures and their electrical properties were investigated. Interconnect structures obtained with the Al dual damascene process using the conventional NH4OH-based wet cleaning (Type I) and the wet cleaning followed by CF4/Ar-plasma dry cleaning (Type II) showed that the metal lines having the aspect ratio of 3 were patterned without gap-filling of inter metal dielectrics. All the sheet resistances of metal lines using the two different wafer cleaning methods during the Al dual damascene process were within specification. The via resistance distributions, however, depended on the cleaning method, and it was found that the cleaning Type II produced a 100% yield and very narrow distribution of the contact resistances of the 0.24 μm-diameter via due to the efficient removal of stable AlxOy species for cleaning Type II.
Polyurea microcapsules containing a pyrethroid insecticide were prepared by the reaction between hexamethylene diisocyanate (HMDI) uretidione/isocyanurate and ethylene diamine (ED) in an oil-in-water (O/W) emulsion. This study was performed to investigate how the concentrations of dimer and trimer affect the characteristics of microcapsules such as the morphology, the wall thickness, the size distribution of microcapsules, the microcapsule yield and mechanical property and to investigate the dust mite repellent effect of the microcapsules adhered to the fabrics. Microcapsules prepared in this study were 0.2–6.0 μm in size and single cored. All the microcapsule yields were almost 98%. It was found that the wall thickness of microcapsules decreases with an increase in the diameter of microcapsules and increases with an increase in the concentration of HMDI uretidione/isocyanurate. The mechanical property was increased with the concentration of HMDI uretidione/isocyanurate. Polyurea microcapsules showed a high dust mites repellent effect.
The behavior of hypochlorite ions and chlorinated organic compounds was investigated using model wastewaters to confirm the by-production of chlorinated organic compounds during the ozonation of wastewater which contains a high concentration of chloride ions such as leachate. An inhibition method for by-production of the chlorinated organic compounds was also studied. A hydrogen peroxide addition method was selected because it was expected to reduce the concentration of both dissolved ozone and hypochlorite ions. The following results were observed. (1) The concentration of the hypochlorite ions by-produced in the effluent increased with the increase of the chloride ion concentration in the influent and the ozone gas addition rate. The hypochlorite ion concentration increased in proportion to the value of t[O3][Cl–]. (2) Inhibition of the hypochlorite ions by-produced during ozonation was achieved by dosing hydrogen peroxide. This effect was caused by the decreased generation rate that resulted from the decreased concentration of dissolved ozone. The disappearance reaction of hypochlorite ions had almost no effect. (3) The concentration of chlorinated organic compounds by-produced in the effluent increased with the increased concentration of chloride ions. Considering the increased concentration of hypochlorite ions and the decreased concentration of dissolved ozone which is resulted from the increased concentration of chloride ions in the influent, by-production of chlorinated organic compounds was caused by the reaction of the hypochlorite ions and organic carbon in the influent. (4) A reduction rate of 61–69% for the chlorinated organic compound concentration in the effluent was obtained by dosing hydrogen peroxide. Hydrogen peroxide inhibited by-production of chlorinated organic compounds. This was caused by the decreased concentration of dissolved ozone which leads to by-production of hypochlorite ions and chlorinated organic compounds. Such a decrease was also observed in UV/O3 combined treatment. These results indicate that, considering the behavior of chlorinated organic compounds, ozonation of wastewaters containing a high concentration of chloride ions such as leachate should be done with hydrogen peroxide dosage.
Recently, we have demonstrated the possible production of clean fuel oils from the municipal waste plastics through hydrothermal pretreatment with aqueous alkaline solutions followed by the thermal liquefaction (Akimoto et al., 2004). In the present work, behaviors of the nitrogen atoms present in nylon, polyurethane and ABS and their interaction with other plastic components during these pretreatment and liquefaction steps have been investigated. When the respective mixtures of the municipal waste plastics with these nitrogen-containing plastics were thermally liquefied at 450°C, the total nitrogen content in oil followed the order of ABS > nylon > polyurethane. In contrast, the total nitrogen content in the carbonaceous residue followed the order of polyurethane > nylon > ABS. Upon hydrothermal pretreatment with 0.2 N NaOH at 300°C, the nitrogen atoms present in these plastic mixtures were eluted in the order of polyurethane > nylon > ABS. In contrast to the nitrogen atoms in polyurethane, thus, the nitrogen atoms in ABS were the most difficult to eliminate at the hydrothermal pretreatment step although they were most likely to remain in oil at the thermal liquefaction step. In contrast to nylon and polyurethane, however, ABS did not always hamper the liquefaction of other plastic components.