Editor-in-Chief
Manabu Shimada (Hiroshima University)

Associate Editor-in-Chiefs
Masahiro Shishido (Yamagata University)
Ken-Ichiro Sotowa (The University of Tokushima)

Editors
Choji Fukuhara (Shizuoka University)
Toshitaka Funazukuri (Chuo University)
Yoshihiro Hashimoto (Nagoya Institute of Technology)
Shunji Homma (Saitama University)
Jun-ichi Horiuchi (Kyoto Institute of Technology)
Yoshinori Itaya (Gifu University)
Masashi Iwata (Osaka Prefecture University)
Noriho Kamiya (Kyushu University)
In-Beum Lee (Pohang University of Science and Technology (POSTEC))
Kouji Maeda (University of Hyogo)
Hideyuki Matsumoto (National Institute of Advanced Industrial Science and Technology (AIST))
Michiaki Matsumoto (Doshisha University)
Nobuyoshi Nakagawa (Gunma University)
Tsuguhiko Nakagawa (Okayama Prefectural University)
Yasuya Nakayama (Kyushu University)
Masaru Noda (Fukuoka University)
Mikihiro Nomura (Shibaura Institute of Technology)
Eika W. Qian (Tokyo University of Agriculture and Technology)
Yuji Sakai (Kogakuin University)
Noriaki Sano (Kyoto University)
Naomi Shibasaki-Kitakawa (Tohoku University)
Hiroshi Suzuki (Kobe University)
Nobuhide Takahashi (Shinshu University)
Kazuhiro Takeda (Shizuoka University)
Shigeki Takishima (Hiroshima University)
Yoshifumi Tsuge (Kyushu University)
Tomoya Tsuji (Nihon University)
Shigeyuki Uemiya (Gifu University)
Da-Ming Wang (National Taiwan University)
Takayuki Watanabe (Kyushu University)
Takuji Yamamoto (University of Hyogo)
Tetsuya Yamamoto (Nagoya University)
Masahiro Yoshida (Kagoshima University)
Yasuo Yoshimi (Shibaura Institute of 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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Choline chloride (ChCl) is a well-known material forming deep eutectic solvents (DESs) when mixed with a hydrogen bonding donor (HBD). The potential applicability of DES systems is wide for replacing ionic liquids at relatively low cost. Therefore, the application to chemical processes necessitates the reliable data of DES properties. In this work, thermal behaviors of two ChCl-based DES systems (ChCl+urea and ChCl+1,3-dimethylurea) were investigated by using a differential scanning calorimeter. Crystalline as well as amorphous characteristics were found by varying compositions. In general, the increased composition of ChCl strengthened the crystallinity of solid phase. In the ChCl+urea system, a phase diagram was drawn with obtained melting point data while it could not be available for the other system.

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A large plate impeller was rotated back and forth in a cylindrical vessel. Simultaneous and continuous measurements of the rotational torque on the mixing shaft and impeller angular position were carried out. The power consumption was computed by integrating the product of the measured torque and impeller rotational speed. The relationship between the power number and Reynolds number revealed that the Reynolds number became small for the transition in power characteristics and that the constant power number became large for the larger Reynolds number region at a small reciprocating amplitude with a large impeller acceleration. This is because a more remarkable startup flow was frequently repeated. The larger power number suggests that the rotationally reciprocating impeller has more efficient power characteristics compared to common rotational impellers. In terms of the torque variation, the measured torque was mainly dominated by the viscous force in the smaller Reynolds number region. As the Reynolds number increased, the phase lag between the torque and impeller speed increased even in the smaller Reynolds number region, and the measured torque was observed to fluctuate in the transition region. Although the measured torque was mainly dominated by the inertia force, the phase lag and magnitude of fluctuation did not increase any further at large Reynolds numbers.

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MFI zeolite membranes with high gas permselectivities were successfully prepared on novel porous silica substrates. Procedures for coating of MFI seed crystals were important due to the ζ-potential between the substrates and the seed crystals. Dense MFI membranes were obtained from the seed slurry of pH 2, because the both isoelectric pH of the silica substrates and the MFI seeds are almost the same at 2. N₂ permeance was 3.7×10⁻⁶ mol m⁻² s⁻¹ Pa⁻¹ with high N₂/SF₆ permeance ratio of 328 through the membrane prepared on the thin silica substrate of 0.8 mm.

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A novel aminophenylthiomethyl chitosan (APTMC) derivative was synthesized by reacting chitosan with 2-aminobenzenethiol, and used to selectively separate precious metals such as gold(III), palladium(II) and platinum(IV) from base metal solutions. Firstly, the adsorption selectivity of APTMC for metal ions in a hydrochloric acid solution was investigated. The adsorption of metal ions on APTMC was dependent on the hydrochloric acid concentration. Gold(III), palladium(II) and platinum(IV) are selectively adsorbed at a lower concentration among hydrochloric acid concentrations, and then their adsorption percentages decrease with increasing hydrochloric acid concentration. This indicates that gold(III), palladium(II) and platinum(IV) can be selectively separated from base metal solutions with APTMC by adjusting the hydrochloric acid concentration. The adsorption equilibria of precious metals such as palladium(II) and platinum(IV) were then quantitatively examined. The adsorption selectivity of palladium(II) from a mixed solution of palladium(II)/iron(III) was demonstrated with APTMC, even in the presence of about a 500-fold excess of iron(III). Finally, the adsorption–desorption cycle of palladium(II) and platinum(IV) adsorbed on APTMC was carried out using an aqueous thiourea solution containing hydrochloric acid. There was no significant decrease in the adsorption capacity on APTMC, indicating that it could be reused 5 times for the adsorption of palladium(II) and platinum(IV).

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A new optical resolution method is proposed in which one enantiomer of a racemic mixture is replaced with a tailor-made additive, and the displaced enantiomer is crystallized. DL-Aspartic acid (Asp) was examined as a model racemic compound. First, L-Asp crystallization was examined in the presence of L-asparagine (Asn) or D-Asn. The effect of Asn was chirality-specific; L-Asn specifically replaced some of the L-Asp in the crystal lattice and solid solutions of L-Asp with L-Asn formed. Secondly, DL-Asp crystallization was examined in the presence of L-Asn, and the obtained crystals were solid solutions of DL-Asp with L-Asn partially replacing L-Asp in the DL-Asp crystal lattice. Finally, crystallization of the L-Asp in the filtrate of the DL-Asp crystallization in the presence of L-Asn was examined. The obtained crystals were a mixture of solid solutions of L-Asp with L-Asn and solid solutions of DL-Asp with L-Asn. Moreover, when D-Asn was added to the DL-Asp crystallization, a mixture of solid solutions of D-Asp with D-Asn and solid solutions of DL-Asp with D-Asn was crystallized from the filtrate. These results show that racemic compounds could be resolved by the proposed method.

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A flue gas desulfurization test bed was built to mainly carry out the desulfurization experiment of marine diesel engine exhaust gas. According to the typical exhaust conditions of marine diesel engines, the experiment was conducted by using washing water. Different Na⁺ concentrations, absorbent pH values, proportions x of SO₄²⁻ and inlet SO₂ concentrations were tested. The gas liquid ratio were in the range 1.5–2.5 L/m³. The desulfurization efficiency model of sodium method washing was also built, making the gas liquid ratio, Na⁺ concentration, and absorbent pH value, the proportion of SO₄²⁻ and inlet SO₂ concentration merge into a dimensionless comprehensive influencing factor ε. Finally, based on fitting the experimental results, it obtained a semi-empirical expression of desulfurization efficiency η and ε was η=f(ε, θ, Φ), of which θ and Φ were empirical parameters related to mass transfer and temperature respectively. Experimental results indicated that desulfurization performance increased with an increase in Na⁺ concentration and absorbent pH value, and it increased with a decrease in the proportion of SO₄²⁻ and inlet SO₂ concentration. At the current operating conditions, the highest SO₂ removal efficiency can be up to 98.7%. A desulfurization efficiency model obtained by further analysis and comparison of experimental data made up for deficiency of engineering design based on experience, providing the basis and reference for independent development of the sodium method ship desulfurization system design software.

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An effective microdevice for extraction has been developed, which is made of acrylic resin for visualization and ease of handling and extracts oil contents from the aqueous phase into the organic phase by using slug flow. The performance of this microdevice was evaluated by carrying out the extraction of sunflower oil from the aqueous phase into the hexane phase. In the case of a volume ratio of 1 : 1 for the sample and hexane, the extraction efficiency reached 68.9% when the total flow rate was 0.4 mL/min (4.0×10⁻⁷ m³/min) and the residence time was 144 s. The generated slug flow was kept stable at shorter residence times, while the generated slug flow became unstable at longer residence times. In the case of a volume ratio of 1 : 2 for the sample and hexane, the extraction efficiency reached 87.3% when the total flow rate was 0.3 mL/min (3.0×10⁻⁷ m³/min) and the residence time was 192 s. The generated slug flow was less stable overall and the slug droplets were observed to partially unite with each other in the downward flow. These flow rates were larger on submilli-L/min (10⁻⁷ m³/min) order and it was easy for this microdevice to handle in terms of the used flow rate ranges. Moreover, this microdevice included not only the slug flow generation area but also the extraction area of oil contents and aqueous/hexane phase separation area. Furthermore, the extraction time per experimental condition was about 8 min and much faster than that with the batch method of the hexane extraction method (at least 2–4 h). Therefore, the microdevice for extraction in this study was found to be effective for improving extraction efficiencies.

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Crystal morphology is important in the production of crystalline particles because the morphology can affect the downstream processes after crystallization, such as solid–liquid separation, and the product quality. In particular, needle-like or plate-like morphology is undesirable in terms of the production of crystalline particles with high purity. Methacrylic acid, which is important as a raw material of specialty acrylates for coating resins, has to be high purity, and purified by melt crystallization. Suspension melt crystallization is suitable for purification because of the large crystal surface area per unit volume. However, methacrylic acid crystals by melt crystallization are long rod-like or needle-like crystals in typical morphology. Therefore, it is desired to improve the morphology of methacrylic acid crystal in the melt crystallization process. The authors have proposed a concept of combining growth and dissolution processes in melt crystallization for a morphology improvement. The objective of this study was to obtain the basic data for a strategy for a morphology improvement of methacrylic acid crystals by controlling the melt crystallization condition. The growth rate and dissolution rate of a single crystal of methacrylic acid were investigated in the major and minor axis directions in terms of supersaturation/undersaturation and additives as impurities (maleic acid, acrylic acid, and water). Based on the ratio of the growth rate in the major axis direction to the growth rate in the minor axis direction opposite to supersaturation, methacrylic acid crystals will easily become needle-like under high supersaturation condition. Therefore, supersaturation should be kept at a low level in order to obtain methacrylic acid crystals with improved morphology. For dissolution, methacrylic acid crystals tended to dissolve in the major axis direction for all of the impurity conditions of mother liquor. From these results, it was concluded that the basic data to discuss a strategy for a morphology improvement of methacrylic acid crystals were obtained.

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The Brunauer–Emmitt–Teller (BET) equation for multicomponent adsorption was derived using assumptions similar to those used in the derivation of the original BET equation. In addition to the assumptions used in the derivation of the original BET equation, the BET equation for mixture adsorption was obtained by assuming that multilayer adsorption in a given layer is independent of the identity of the molecule adsorbed beneath it in the previous layer. The adsorption and desorption processes were considered to be reactions and the expression for the equilibrium concentration on surface was obtained using the equilibrium constants of the reactions. The performance of the BET equation derived for mixtures was compared with that of the widely used extended Langmuir equation using some selected binary adsorption isotherm data shown in the literature. The performance of the BET equation derived in this work was better than that of the extended Langmuir equation in the prediction of adsorbed phase concentrations and adsorbed amounts for the binary systems considered in this work.

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A new type of double inverse opals (DIOs) in which a single inorganic sphere was embedded within each inorganic compartment formed by nanoparticles was fabricated via binary colloidal crystals (BCC) composed of submicron-sized core-shell spheres and the nanoparticles. In the fabrication of BCC, submicron-sized silica cores coated with a polystyrene shell and silica nanoparticles with sizes one-tenth smaller than that of core-shell particles were employed as the core-shell spheres and the nanoparticles, respectively. The BCCs fabricated were heated at 550°C for 5 h to selectively remove the polystyrene shell from the BCCs, resulting in mono-layered silica cores embedded in each hemispherical compartment without any overlayers preventing the submicron-sized cores from being optically and physically interacted with the outside. The present work provides a facile fabrication method for inorganic DIOs that will be used for new colloidal architectures.

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As CO₂ is the largest contributor to the greenhouse effect, reducing the total CO₂ emissions into the atmosphere has been considered as the breakthrough point of mitigating the greenhouse effect. Mineral carbonation is a potential route for CO₂ sequestration. In this paper, the mineral carbonation reaction characteristics of wollastonite, serpentine and olivine under low-medium pressure conditions were investigated. Many tests including XRD, XRF, BET and thermal decomposition were applied. Parameters, such as reaction temperature, reaction pressure, particle size, solution composition and heat-treatment, were discussed in details. The results show that besides increase of reaction temperature and pressure, addition of NaHCO₃ and decrease of particle size can also effectively accelerate the carbonation reaction for all the three minerals. Heat-treatment of minerals is only useful for serpentine. Highest carbonation conversion efficiency of 83.5%, 47.7% and 16.9% was respectively achieved for wollastonite, serpentine and olivine under the condition of T=150°C, P=40 bar and particle sizes <30 µm. Compared the conversion efficiencies, it is indicated that wollastonite was the most reactive mineral and olivine was suggested to be not suitable for CO₂ sequestration by direct aqueous mineral carbonation under low-medium pressure conditions.

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