The liquid–liquid equilibria of the three ternary systems: water + 2-butanone + aliphatic alcohols (ethanol, 2-proponal, and 1-proponal) were each measured at 288.15, 298.15 and 308.15 K. Experimental data were correlated as a linear function of temperature using the UNIQUAC equation with the dimensionless parameters, τij. The root-mean-square-deviations between the correlated and experimental mole fractions were evaluated as 1.37, 0.87 and 1.16% for water + 2-butanone + ethanol, water + 2-butanone + 2-propanol and water + 2-butanone + 1-propanol, respectively.
We have carried out the molecular dynamics simulations to investigate not only the structural and dynamical properties of single solutes of the sodium cation (Na+), the chloride anion (Cl–), the tetramethylammonium cation (TMA+), and the methane molecule (CH4) in ambient water at infinite dilution, but the hydration structures and the potentials of mean force (PMFs) for the Na+–CH4, the Cl––CH4, the TMA+–CH4, and the Na+–TMA+ pairs. As a result, it is confirmed that the results of the diffusion coefficients of the four solutes are in quantitative agreement with the experimental data and that the monovalent ions in water exhibit three classes of hydrations, the structure-making hydration (Na+), the structure-breaking hydration (Cl–), and the hydrophobic structure-making hydration (TMA+), depending on the charge density determined by the ion size. A detailed comparison among the PMFs for the Na+–CH4, the Cl––CH4, and the TMA+–CH4 pairs indicates that, as for the monovalent ion–methane pairs in water, the increase of the ion size diminishes the instability of a contact solute pair due to the compactness of the hydrated ion and enhances the stability of a solvent-separated solute pair concurrently at the longer distances. The PMF and its solvent contribution for the TMA+–CH4 pair are quite similar to those for the apolar CH4–CH4 pair, probably because both the TMA+ and the CH4 exhibit hydrophobic hydration. For the same reason, the PMF for the Na+–TMA+ pair is qualitatively akin to that for the Na+–CH4 pair.
A model for the prediction of bubble growth at a submerged orifice in a viscous liquid has been presented. An interfacial element method is applied to calculate the bubble growth shape and detachment. Simulated bubble volumes are compared with experimental data for a wide range of viscosity and surface tension. Model predicted results were found to compare well with the experimental data within ±15% except for systems within the creeping flow regime.
Changes in the mobility of bipolar ions due to water vapor in the medium gas and the effect of the change on the aerosol particle charging states were investigated, both experimentally and theoretically. Particle charging equations regarding the mobility distributions of bipolar ions were also derived from basic particle charging equations (Marlow and Brock, 1975; Adachi et al., 1985; Reischl et al., 1996) and confirmed by comparison with experimentally obtained data. For positive ions, the peak electrical mobility was very stable and independent of water vapor concentration, but for the case of negative ions, a considerable increase with water vapor concentration was found. The change in negative ion mobility had a more significant effect on the positive charging ratio of aerosol particles than a negative one, indicating that negatively charged particles are more amenable than positively charged ones to aerosol particle measurement using a differential mobility analyzer. Since a better agreement was found between experimental and calculated results by the solution for the ion mobility distribution than the basic charging equation, it would be expected that particle charging equations regarding mobility distribution would be applicable to a determination of particle charging ratio when many types of bipolar ions are simultaneously present in a particle charging space.
Ultrasound was irradiated during solutes permeation through a dialysis membrane. Since a power ultrasound leads to cavitation which can damage the membrane structure, cavitation-free condition was carefully selected. Applying ultrasound increased a few tens percent of steady-state permeation rate. Furthermore, a sudden increase or decrease of the solute concentration on the receiving side was observed. Such a stepwise concentration change is partly explained from the thinning and developing of liquid film adjacent to the membrane surface with and without applying ultrasound. Effects of ultrasound on solute trasnfer were reversible and no damage of the membrane structure was found by SEM observation. Moreover, the liquid flow near the membrane surface was visualized with and without ultrasound. Under a slower flow situation, standing wave was formed in the vicinity of the membrane, and the solute permeation was enhanced by ultrasonic irradiation. While under a faster flow, the standing wave was disturbed and no enhancement was observed for the solute permeation. Moreover, ultrasonically enhanced mass transfer coefficient for slower flow was bigger than that for faster flow. This fact implies that the standing wave adjacent to the membrane surface closely relates with the enhancement of solute permeation through the membrane.
SrFeCo0.5Ox asymmetric membranes for oxygen permeation consisting of a thin dense layer and a porous support layer were prepared using a simple method. A given amount of SrFeCo0.5Ox powder was placed in a die, and then a mixture of SrFeCo0.5Ox powder and ethyl cellulose powder was added on top of the SrFeCo0.5Ox powder. The layered powders were pressed into a 13 mm-diameter disk, and calcined at 1423 K. This produced a membrane with a thin dense layer and, through the elimination of the ethyl cellulose, a porous support layer. Oxygen flux through membranes thus produced increased with decreasing dense-layer thickness. The maximum oxygen flux through an asymmetric membrane at 1173 K observed was 0.23 cm3 (STP) cm–2 min–1, which was 2.8 times larger than that through a 0.95 mm-thick symmetric membrane. Oxygen permeation was primarily limited by bulk diffusion in the thin dense layer, although the porous support layer acted to resist oxygen permeation.
When air was bubbled into a ferrous ion solution maintained at pH = 10.0, magnetite was precipitated due to oxidation of ferrous ion in the aqueous phase. The total concentrations of ferrous and ferric ions were measured over time in a three-phase system (air, solution and precipitated magnetite). The total concentration of ferrous and ferric ions linearly decreased with time until about 10% of the initial ferrous concentration remained according to the equation,
[Fe] = [Fe]0(1 – αt)
The overall rate constant, α, increased with a decrease in the initial ferrous concentration and with an increase in the flow rate of air. The overall rate constant could be interpreted by the reaction model taking into account the oxygen absorption rate as well as chemical reaction rates in the aqueous phase. The overall reaction rate was limited by the oxidation rate of ferrous ion. The rate constant of the oxidation depended on the initial ferrous concentration, the air flow rate and the air dispersion state. The decrease in the magnetite formation rate in the late stage may be interpreted qualitatively as being due to the surface of the ferrous hydroxide becoming covered with magnetite.
During the synthetic process by chemical vapor synthesis, the influence of temperature and gas flow rate on the size of gallium nitride (GaN) nanoparticles was studied. The mean size of the narrow-dispersed GaN nanoparticles increased as the temperature rose to within a range between 800 and 1100°C. At 700°C, however, GaN nanoparticles were not produced. A faster gas flow resulted in a reduction in the particle size at the ammonia/trimethylgallium ratio of 2400 but not obvious at 1200. These findings can be explained as “coagulation and sintering control regime” and partially as nucleation frequency of GaN nanoparticles.
A shell-and-tube absorber and an ammonia absorption refrigeration (AAR) system were constructed to study falling film absorption on a horizontal tube. An empirical and numerical combined method (ENCM) was developed to estimate the actual falling film thickness using parametric analysis with a simplified mathematical falling film model and experimental results. Numerical and experimental studies showed that the simplified mathematical falling film model has an exact physical response about ammonia absorption process in the absorber. The temperature difference of solution decreases with the increasing inlet coolant temperature. The heat transfer performance of a real type shell-and-tube absorber with the AAR system is a more sensitive function of the coolant inlet temperature than the solution inlet temperature. The ENCM developed in the present study can be used to estimate the actual thickness of a falling film along a horizontal tube in the shell-and-tube absorber of the AAR system, which is very difficult to measure experimentally. The ammonia absorption rate decreases with inlet temperature of a weak ammonia solution and inlet coolant temperature.
CEM (Continuous Emission Monitors) techniques need to be developed for the appropriate control of volatile heavy metals contained in the flue gas from waste incineration. LIBS (Laser Induced Breakdown Spectroscopy) is one of the promising methods for the real-time and in situ measurement of trace elements in a gas. All the elements existing in a laser-induced plasma are excited and radiate characteristic line spectra. These spectra enable the identification and quantification of each element. In order to gain a foothold in the online measurement of cadmium in flue gas using LIBS, the midgut gland of scallop, known to be a waste product having an extremely high concentration of cadmium, was selected as a combustion sample. The transient change in cadmium emission from midgut gland combustion was continuously analyzed using LIBS.