Editor-in-Chief:
Hiroyuki Honda (Nagoya University)

Associate Editors-in-Chiefs:
Manabu Shimada (Hiroshima University)
Takao Tsukada (Tohoku University)

Editors:
Ryuichi Egashira (Tokyo Institute of Technology)
Jun Fukai (Kyushu University)
Choji Fukuhara (Shizuoka University)
Takayuki Hirai (Osaka University)
Masahiko Hirao (The University of Tokyo)
Jun-ichi Horiuchi (Kitami Institute of Technology)
Eiji Iritani (Nagoya University)
Yoshinori Itaya (Gifu University)
Hideo Kameyama (Tokyo University of Agriculture and Technology)
Masahiro Kino-oka (Osaka University)
Toshinori Kojima (Seikei University)
In-Beum Lee (Pohang University of Science and Technology (POSTEC))
Kouji Maeda (University of Hyogo)
Shin Mukai (Hokkaido University)
Akinori Muto (Osaka Prefecture University)
Nobuyoshi Nakagawa (Gunma University)
Hiroyasu Ogino (Osaka Prefecture University)
Naoto Ohmura (Kobe University)
Mitsuhiro Ohta (The University of Tokushima)
Yuji Sakai (Kogakuin University)
Noriaki Sano (Kyoto University)
Masahiro Shishido (Yamagata University)
Richard Lee Smith, Jr. (Tohoku University)
Hiroshi Suzuki (Kobe University)
Shigeki Takishima (Hiroshima University)
Yoshifumi Tsuge (Kyushu University)
Tomoya Tsuji (Nihon University)
Da-Ming Wang (National Taiwan University)
Yoshiyuki Yamashita (Tokyo University of Agriculture and Technology)
Miki Yoshimune (National Institute of Advanced Industrial Science and Technology (AIST))

Editorial office:
The Society of Chemical Engineers, Japan
Kyoritsu Building, 4-6-19, Kohinata, Bunkyo-ku
Tokyo 112-0006, Japan
journal@scej.org

AIMS AND SCOPE:

Journal of Chemical Engineering of Japan, an official publication of the Society of Chemical Engineers, Japan, is dedicated to providing timely original research results in the broad field of chemical engineering ranging from fundamental principles to practical applications. Subject areas of this journal are listed below. Research works presented in the journal are considered to have significant and lasting value in chemical engineering.

Physical Properties and Physical Chemistry
Transport Phenomena and Fluid Engineering
Particle Engineering
Separation Engineering
Thermal Engineering
Chemical Reaction Engineering
Process Systems Engineering and Safety
Biochemical Food and Medical Engineering
Micro and Nano Systems
Materials Engineering and Interfacial Phenomena
Energy
Environment
Engineering Education

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In vitro release of ketotifen from transdermal systems made of silicone pressure-sensitive adhesive matrices (PSA) containing crystalline ketotifen (PSA-Crystalline) and that containing amorphous ketotifen (PSA-Amorphous) were analyzed using two types of mathematical models. Higuchi’s model, which assumes an infinite drug dissolution rate in the matrices, well described the release from PSA-Amorphous. While Higuchi’s model overestimated the release from PSA-Crystalline, the deviation was significantly diminished by incorporating a dissolution control term into the model. This analysis suggests that ketotifen release from PSA-Amorphous is almost entirely diffusion-controlled, while that from PSA-Crystalline is controlled by both diffusion and dissolution processes.

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A metallothermic reduction technique was adopted to reduce rare earth oxides in a molten LiCl. A reducing agent of Li was supplied to the system by dissolving excess amount of Li metal on a separated section in a reactor. The extents of the reduction were measured by analyzing Li₂O which is the product of the chemical reactions. Nine kinds of rare earth oxides in the form of RE₂O₃ were partially reduced to the corresponding metals until the Li₂O concentrations reached certain critical values for each reaction. The Li₂O activity coefficients were evaluated based on the measured critical concentrations. These experimental results gave important information concerning the chemical behavior of rare earth oxides during an electrochemical reduction process which will be utilized to reduce spent oxide fuel in a pyroprocessing scheme.

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The coefficients of estimation equations required to evaluate the interaction parameters between unlike molecules from pure–component properties are reported for alcohol+hydrocarbon binary systems. By using the equations, the Wilson parameters can be estimated, and the vapor–liquid equilibria (VLE) of the mixtures can be predicted on the basis of a previously proposed method.

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This study investigates improvements in high-resolution elution chromatography of proteins loaded to a bed charged by way of cation-exchange polymer-brush-immobilized particles. A sulfonic acid group as a cation-exchange group was introduced into a polymer brush grafted onto a polyethylene particle with an average diameter of 35 µm. A bed charged with the resulting cation-exchange polymer-brush-immobilized particles, SS bed, has a sulfonic acid group density of 0.36 mmol/mL-bed. A mixture of α-chymotripsinogen A (chy), cytochrome c (cyt), and lysozyme (lys) was loaded onto the SS bed. The subsequent linear gradient elution performance of the proteins adsorbed by the SS bed with 20 mM phosphate buffer (pH 6.0) and 1 M NaCl is compared with those by commercially available cation-exchange-bead-packed beds. The resolutions of the SS bed of both the chy/cyt and cyt/lys pairs at a linear velocity of 600 cm/h exceeded 1.9 at a loading amount of 0.8 mg/mL-bed, which was not achieved using the beds charged with SOURCE® 30S, POROS® 50HS, or Fractogel® EMD SO₃⁻ (s). Even at a loading amount of 12 mg/mL-bed, the resolutions of the SS bed for the chy/cyt and cyt/lys pairs at a linear velocity of 300 cm/h were 1.4 and 2.7, respectively.

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A gas–liquid two-phase plunging jet is formed through an ejector type nozzle using a perforated plate. Absorbers that use such a jet have a high gas holdup and a large product of liquid-phase mass transfer coefficient and gas–liquid interfacial area, (k̅_LA)_T. In the present study, the dependence of the gas holdup and bubble diameter on the nozzle geometry and column diameter was investigated experimentally. An equation for the gas holdup was derived based on physical considerations. The mass transfer mechanism for all of the experimental data was analyzed using a coaxial bi-zonal model. The dependence of the liquid phase mass transfer coefficient k̅_LT and specific gas–liquid interfacial area a_T on the column diameter D_T was evaluated. The gas holdup was found to be a function of the equivalent diameter d_e; total energy of the liquid jet, E_T; and D_T. The behavior of this absorber can be explained using the coaxial bi-zonal model across all of the data. The (k̅_La)_T value for the plunging jet absorber can be enhanced by decreasing D_T; further, a_T showed a weak dependence on D_T. The changes in k̅_LT were influenced by an increase in the ratio of the gas–liquid interfacial area in the peripheral annular zone to that in the core zone. Therefore, the changes in (k̅_La)_T against the energy loss per unit volume of liquid, E_T/V_L, were dependent on the changes in (k̅_La)_T with E_T/V_L. The design of the plunging jet absorber showed that a nozzle diameter D_N of 1 cm and D_T of 5 cm were desirable under the experimental conditions.

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Defatted roselle seed, a by-product of roselle calyx, was considered as a source of antioxidants. The feasibility of subcritical water extraction to release phenolic compounds in defatted roselle seed was investigated. The optimization of subcritical water extraction was obtained by a response surface methodology. The effect of different solvents used to obtain defatted roselle seed on the phenolic extraction was also studied. Defatted roselle seed contains valuable phenolic compounds that show high antioxidant activity. p-Coumaric acid and ferulic acid are the major phenolic compounds found in defatted roselle seed. Under optimum conditions, the subcritical water extract obtained has a phenolic content 12 times that of defatted roselle seed. The extract has a total phenolic content of 56.72 mg gallic acid equivalent per gram extract (analyzed by the Folin–Ciocalteu method), or 22.29 mg per gram extract (by HPLC analysis) and a 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging activity of 84.0% at a concentration of 2.5 mg/mL.

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This paper describes an easier and more effective method for producing a colloidal solution in which flocculated nanoparticles become re-dispersed by using a back pressure valve. Initially, a solution of nanoparticles (CdSe/ZnS-core/shell quantum dots) is left to flocculate by storing water-soluble nanoparticles (modal diameter 13.5 nm) for 2 d at 40°C. A large shear stress is applied to the solution in a back pressure valve for re-dispersing the flocculated particles. The clearance of the flow path in the valve decreases with increasing primary pressure. The re-dispersibility is evaluated through the measurement of their size distribution and zeta potential using dynamic light scattering (Zetasizer). The results show that the method re-dispersed the flocculated particles and reduces their modal diameter from over 6000 nm to 21.0 nm. Additionally, increasing the pressure decreases the particle diameter after the re-dispersion. The re-dispersed particles have a larger effective surface area than those of flocculated particles and, therefore, a larger zeta potential. In addition, we identify the mechanism of re-dispersion in this valve from the ratio of the applied shear stress or the colliding force against the channel wall compared to the van der Waals interaction energy. From the results, shear stress dominates the re-dispersion of flocculated particles. Moreover, we can predict the particle diameter after the re-dispersion from the dispersion numbers Di₁ (the ratio of the shear stress to the van der Waals interactive energy) and Di₂ (the ratio of the collision force to the interactive energy). Finally, the re-dispersed particles are confirmed to provide the equivalent medical activity to that of the samples immediately after synthesis.

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A thermosetting bioplastic was formed by heating a bioplastic prepolymer consisting of glucose and modified MDI (carbodiimide-modified 4,4′-diphenyl methane diisocyanate). This plastic, formed by a hot stamping device, had the same quality (bending strength) as phenolic resin. However, the bending strength deteriorated after a long heating treatment. The optimum heating time was around 300 s and the cure ratio reached 60–80% at the average heating temperature of 430 K during the industrial manufacturing process. The cure ratio of the bioplastic prepolymer could be roughly estimated by measuring the change in color (hue value of microscopic image). The time courses of the cure ratio during heating could be simulated by a kinetic model. Both methods will be useful for process management during the production of thermosetting bioplastic as a replacement for phenolic resin. The results of this study will be very important for the industrial manufacturing of thermosetting bioplastic.

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