Ionic liquids are regarded as environmentally friendly solvents because of their low volatility. First, this review reports a literature search of thermophysical properties of ionic liquid systems. Second, it gives correlation and prediction tesults of thermophysical properties for pure ionic liquids and ionic liquid+solvent systems. Third, it considers solvent selection for extractive distillation and liquid–liquid extraction, separation membranes and heat pipes.

View full abstract

Satoh's equation (Satoh et al., 1991) was modified to estimate the power consumption in gas–liquid stirred vessels with various types of impellers. N_p and f was added in order to use a correlation equation widely (f: correction factor for special shaped impeller and large scale impellers, N_p: power number without aeration). Power consumption was correlated by the following equation.

The value of β was about 1.2 to 1.3 for general impellers (disk turbine, pitched disk turbine, flat paddle and pitched paddle) and about 1.2 for large scale impellers (MAXBL^TM and FULLZONE^TM). By using this equation, the power consumption of general impellers and large scale impellers can be presumed with sufficient accuracy.

View full abstract

The aerated power consumption and the volumetric mass transfer coefficient were measured in a mixing vessel without baffles and with weak baffle conditions, equipped with dual impellers that combined a concave turbine and a Rushton turbine with a large ring sparger. When the ratio of sparger diameter to impeller diameter was ≥1.3, no decrease was observed in aerated mixing power consumption. It was shown that the volumetric mass transfer coefficient for a vessel without baffles and even with weak baffle conditions can be calculated by the correlation of Sato et al. (1989).

View full abstract

A new apparatus was developed to evaluate the flowability of particles with poor flow behavior. This apparatus uses the phenomenon that particles drain from a particle-bed as stress on the bed is gradually increased. Samples employed were coarse particles with good flow behavior (133, 158, 306 µm) and fine particles with poor flow behavior (1.6, 4.5, 32.9 µm). The drained angles of coarse particles obtained with the new apparatus agree with those obtained with a conventional apparatus. Hence, the new apparatus is applicable for coarse particles. On the other hand, the drained angles of the fine particles could not be measured by the conventional method, as particles did not drain from the container. However, with the new apparatus, a particle-bed of fine particles (≤4.5 µm) suddenly collapsed drained at a certain level of applied stress. From this stress value, the forces acting between particles in the bed were calculated, and these forces agreed with those obtained with a direct shear tester. Thus, the new apparatus can also be used to estimate shear stress. Furthermore, the apparent drained angle is proposed as a new flow property for particles with poor flow behavior, and this allows the flowability of these particles to be evaluated.

View full abstract

We have previously demonstrated that our theoretical analysis method is useful for the prediction of flux change in the nanofiltration of dairy whey in a batch concentration system. In this study, we attempted to predict the flux change in whey nanofiltration in a complex batch concentration system with a circulation loop, which is used in practice for membrane filtration in food processing. Reconstituted whey solution (approximately 0.1 t), prepared from a commercial whey powder, was concentrated 2.2-fold by weight by nanofiltration (membrane surface area; 7.4 m²) in a batch concentration system with a circulation loop. The reconstituted whey solution in the feed tank was transferred to a membrane module. Part of the retentate was directly supplied to the membrane module via the circulation loop, and the residual retentate was returned to the feed tank.
The flux changes were measured during the concentration process under three sets of operating conditions: 1) input flow rate to inlet of NF module 2.5 m³/h, operating pressure 1.2 MPa, with circulation loop; 2) 2.5 m³/h, 1.7 MPa, with circulation loop; 3) 1.0 m³/h, 1.2 MPa, without circulation loop.
A new approach was adopted in this study. The characteristic values of whey at the inlet of the NF module, which could not be measured by sampling, were calculated using the measured results of retentate and feed tank whey and their mass balance. In the theoretical analysis, solute quantities in the whey are classified into two parts, namely, the membrane permeable solute and the membrane non-permeable solute. The transportation equation and concentration polarization equation were used in the same way as in our previous report (Seki et al., Kagaku Kogaku Ronbunshu, 38, 90–101, 2012).
The analytical results show that the characteristic values of whey were almost constant under all experimental conditions investigated, and the predicted fluxes matched well with the measured fluxes. The new analytical method developed in this study could therefore predict the flux changes in a batch concentration system with a circulation loop.

View full abstract

High-level deliquoring of excess municipal activated sludge was accomplished by use of an inorganic flocculant, polyaluminum chloride (PACl), and an organic polymer flocculant, Kurifix. The deliquoring process consisted of filtration of flocculated sludge followed by ultrahigh-pressure expression combined with water permeation through the filter cake, resulting in the re-distribution of flocs in the filter cake. Whereas the use of Kurifix increased the filtration rate significantly more than PACl, it decreased the expression rate, particularly at low expression pressure. As the expression pressure increased, the cake moisture content decreased more remarkably in the case of PACl compared with Kurifix. Of particular interest is that an ultrahigh pressure of 50 MPa decreased the cake moisture content to 23.7 wt% at the end of expression. The kinetics of ultrahigh-pressure expression such as the variations with time of the average consolidation ratio and average cake moisture content was well elucidated by considering a Terzaghi type of primary consolidation followed by a mainly two-stage creep phenomenon. Consequently, the creep effect was marked in the case of Kurifix, particularly at low expression pressure. Moreover, the modified consolidation coefficient increased with the expression pressure and remained constant above a critical expression pressure, which depended on the flocculant: ca. 5 MPa for PACl and ca. 10 MPa for Kurifix.

View full abstract

Impregnation was used to affix bis(2-ethylhexyl) phosphate (HDEHP) to the dodecylamino group of a polymer chain grafted onto a 6-nylon fiber. The distribution coefficients of Nd and Dy ions on the fiber agreed well those for HDEHP in dodecane. HDEHP supported on the hydrophobic graft chain was found to behave similarly to HDEHP dissolved in organic solvent. Nd and Dy ions were successfully separated by elution chromatography with an HDEHP-impregnated fiber-packed bed, and leakage of HDEHP from the bed was found to be negligible during the chromatography.

View full abstract

This study aims to elucidate the phenomena of the coagulation and cooling process of the phase-change thermal storage medium sodium acetate trihydrate. The three-dimensional coagulation and cooling process of pure sodium acetate trihydrate without additives during thermal storage in the liquid phase were visualized using an infrared camera and a video camera in a horizontal enclosed rectangular container and a horizontal rectangular container with a free surface. Image processing based on the acquired visualization data was carried out with a computer, and various physical quantities peculiar to the cooling process were elucidated experimentally. As a result, we clarified for the first time the relation between the degree of critical supercooling and the average cooling velocity. Moreover, the influence of the degree of critical supercooling on the coagulation process was clarified three-dimensionally and phenomenologically using a series of visual and thermal images.

View full abstract

The performance of mesoporous silica catalysts in hydrolysis of cyclosiloxanes was measured in a fixed-bed reactor under various experimental conditions in order to protect the hydrogen recombination catalyst used in the off-gas treatment system of a boiling water reactor from poisoning by cyclosiloxanes. The hydrolysis of decamethyl cyclopentasiloxane (D5) over Zr-SBA15 and Ti-SBA15 was found to depend on the residence time but not on the reaction temperature or the amount of catalyst loaded on the honeycomb (100–150 g/L). The conversion of D5 by hydrolysis over Zr-SBA15 was 0.95 at 423–523 K with a linear velocity of 2.9 m/s in a honeycomb of 120 mm in height. The hydrolysis of D5 over Zr-SBA15 and Ti-SBA15 was a first-order reaction and the conversion of D5 could be predicted from an Arrhenius plot. In a DSS durability test, the performance of Ti-SBA15 declined less than that of Zr-SBA15.

View full abstract

The growth rate of titanium nitride (TiN) film by thermal chemical vapor deposition (CVD) in horizontal tubular reactor was investigated experimentally and numerically. Titanium tetrachloride (TiCl₄) was selected as a raw material, and TiCl₄ vapor was mixed with nitrogen and hydrogen in the reactor. The initial molar fraction of TiCl₄ was about 0.0003, and the pressure at the exit of the reactor was about 50700 Pa. There were two regions for the growth rate distribution along the axis in the tubular reactor. In the first region, the growth rate could be controlled by the surface reaction of TiCl₄ because it increased with temperature at the inner wall, T_IW, of the reactor. In this region, analysis of reaction kinetics for a differential reactor showed that the rate constant for the surface reaction increased with the temperature at T_IW<1163 K and did not change at T_IW>1163 K. In the second region, the growth rate was found to decrease exponentially with axial position in the reactor and could be controlled by the diffusion rate of remaining TiCl₄. The growth rates of the TiN film calculated by combining heat and mass transfer analysis with the nonlinear least-squares method agreed well with the experimental ones. The activation energy for the rate constant of the surface reaction was 201.9 kJ/mol.

View full abstract

Aldehyde oxidase (AOX)-immobilized silica gel (AOX-SG) was developed as a means to remove formaldehyde in the gas phase by enzyme degradation. AOX from the formaldehyde-tolerant microorganism Paecillomyces variotii IRI017, which we newly isolated from soil, was utilized. Amino group-binding silica gel (AminoSG) was prepared by APTE (3-aminopropyl triethoxysilane) treatment. All types of AOX-immobilized silica gels were oven-dried at 50°C to constant weight, and formaldehyde degradation by the dried AOX-SG or AOX-aminoSG was examined. Humidified air containing 0.4–0.5 ppm of formaldehyde was passed continuously through SG columns packed with one of four types silica gels: SG, AminoSG, AOX-SG, and AOX-aminoSG. Formaldehyde in test air was removed in the early period in all types of SG by adsorption. With SG and AminoSG, however, formaldehyde removal decreased sharply and become zero within 20 d because of saturation of the gel by formaldehyde. With AOX-SG and AOX-aminoSG, removal of more than 90% of formaldehyde continued for more than 90 d. These results suggest that formaldehyde in the test air was adsorbed by silica gels and degraded by immobilized AOX.

View full abstract

In this study, we examined the immunostimulatory effects of powder from barley-shochu distillation remnants (PSDR) on a human natural killer (NK) cell line, KHYG-1, in vitro. Treatment of NK cells with PSDR induced the expression of NKG2D, an activating NK receptor on the cell surface, and increased the cytotoxicity toward NK-sensitive target leukemia (K562) cells and NK-resistant target hepatoma (HepG2) cells. On the other hand, treatment of K562 cells with PSDR induced ligands (MICA/B) for NKG2D on the cell surface and increased the sensitivity to NK cells. These results show that PSDR has immunostimulatory effects in vitro resulting from increased cytotoxicity of NK cells to cancer cells.

View full abstract

A solid material prepared from concrete sludge, PAdeCS®, an industrial waste consisting of surplus concrete from concrete product industries and construction sites, was applied to a phosphorus recovery process with a packed-bed flow system. Sieved particles of PAdeCS were packed in a plastic column, and a model wastewater of pH 7 containing 100 mg-P/L of potassium dihydrogen phosphate (KH₂PO₄) was fed into the column. The concentration of phosphorus in the effluent solution remained as low as about 0.1 mg-P/L before the breakthrough time and increased rapidly thereafter. The amount of model wastewater that can be treated by the present system was found to increase with the height of the packed layer. The removal of phosphorus is thought to occur by the formation of hydroxyapatite (HAP) from calcium ions and hydroxyl ions dissolved from the hydrated cement components in PAdeCS and phosphorus ions in the model wastewater. The formation of HAP occurred at the surface of the packed layer of PAdeCS as well as the formation of HAP crystals in the bulk solution phase. The ratio of HAP formation, which is equivalent to the phosphorous recovery ratio, was found to depend on the height of the PAdeCS layer and the flow rate of the model wastewater.

View full abstract