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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Outstanding Paper Awards Subcommittee of Journal of Chemical Engineering of Japan has assessed the 131 papers published in volume 47 into 2014, and the editorial board finally selected the five papers for JCEJ Outstanding Paper Awards of 2014; those are the papers on “Mechanism of the Initial Phenomena of Defluidization Caused by Switching Fluidizing Gases,” “Purification of Pt-Loaded Carbon Nanoparticles by Dielectrophoresis,” “Reaction Analysis of Ethanol Electro-Oxidation on PdRu/C Catalyst at Intermediate Temperature,” “Novel Nickel Catalysts Based on Spinel-Type Mixed Oxides for Methane and Propane Steam Reforming,” and “Prediction of Molten Steel Temperature in Steel Making Process with Uncertainty by Integrating Gray-Box Model and Bootstrap Filter.”

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Mixing times for large impeller, Maxblend, Hi-F Mixer and Sanmeler in addition to double helical ribbon were measured precisely in a wide range of Reynolds number. As well known, the dimensionless mixing times for helical ribbon impeller become nearly constant in the laminar flow region. On the other hand, it was recently reported that those for Maxblend are almost inversely proportional to the Reynolds number. In this work, the mixing times and power consumptions were investigated experimentally for Hi-F Mixer and Sanmeler, which have inclined upper blade in addition to a large bottom paddle and are the other types of large impellers than Maxblend, and compared with those obtained in this work for Maxblend and double helical ribbon impeller. As a result it was found that the dimensionless mixing times for Hi-F Mixer and Sanmeler also decrease but more slowly with an increase in Reynolds number than those for Maxblend. The difference in dependencies of mixing times on Reynolds number were explained by the geometrical configurations of these large impellers.

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While the chaotic degree can be efficiently increased by the temporal terms such as co-reverse periodic rotational impeller speed and time-periodic fluctuation of rotational impeller speed, the approach is nevertheless limited in practical applications because of the restriction of the motor and the speed reducer machine. Practically, the temporal approach has rarely been employed in the mixing operation in the process industries, except for washing machines. In contrast, the spatial way can also increase the chaotic degree by reducing the circumferential symmetry and shifting the complexity of the attractors or strange attractors in normal mixing equipment. In fact, the spatial way does not improve the mixing performance as impressively as the temporal way, but it has less demanding requirement on the machines. Consequently, the approach has been widely used in industry, however the comparison among the mixing performances of different spatial chaotic mixing methods has almost never been reported.
In this work, we measured the mixing times and power consumptions for several different spatial chaotic mixing methods, such as an off-center impeller, inclined impeller and inserting an object in identical agitated vessels agitated by the same impeller, and the comparison of mixing performances among these methods was conducted. As a result, it was found that the inserting of an object is the best method among the spatial chaotic mixing methods to achieve a short mixing time at a low power consumption.

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It is not clear how the gas holdup of a solution containing microbubbles changes with the use of different surface-active agent coating microbubbles. This study investigated how the gas holdup of an aqueous solution containing microbubbles relates to the dynamic surface tension of the solution and the surface charge of surface-active agents coating the microbubbles. Microbubbles were generated using a static mixer. When a non-ionic organic chemical was used as the surface-active agent, the gas holdup increased with a decrease in dynamic surface tension. A similar trend was observed for sodium alkyl sulfate, alkyl trimethylammonium chloride, and polyoxyethylene dodecyl ether. However, the gas holdup in aqueous solutions of an ionic surfactant was more sensitive to the change in the dynamic surface tension than that of nonionic surfactant. The effect of electric charge on a surfactant on the gas holdup was examined using an amphoteric surfactant, i.e. N-lauryl β-aminopropionic acid. Its chemical structure changes with solution pH, resulting in a change in ionicity. The gas holdup was a minimum at the isoelectric point of the amphoteric surfactant (pH 4.0). Thus, this study proved that gas holdup depends on the dynamic surface tension of the solution and the surface charge of microbubbles.

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Based on the studies about the mass transfer of a falling film flow and irreversible thermodynamics, a new multi-stage flash model is proposed to analyze the mass transfer process of falling film evaporation. The evaporation of a falling film is regarded as an interrelated multi-stage flash process in the model, and explains how to save energy during the separation of a binary-component system. By comparing the separation performance of different heating conditions and simulation, the multi-stage flash model is proven reasonable in explaining the mass transfer process of falling film evaporation. In the experiments, the mass transfer efficiency of uniform heating increases over 8% compared with concentrated heating. The multi-stage flash model provides a theoretical basis to improve energy efficiency, and provides a new research approach to analyze the mass transfer of falling film evaporation.

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The mathematical formulation of a heat transfer flow problem was developed assuming a laminar velocity distribution in both inner and annular channels with ignoring axial conduction, and the analytical solution was obtained using an orthogonal expansion technique in terms of power series. Qualitative agreement was achieved between the analytical solutions and the experimental results. Comparisons made between the results from the double-pass concentric circular heat exchanger and those in a single-pass device (open conduit) are presented graphically. A considerable improvement in heat transfer is obtainable by employing double-pass devices instead of single-pass.

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In this study, an organic reagent was used as a leaching reagent for copper extraction from copper oxide ore. The effects of several factors, including leaching time, temperature, particle size, reagent concentration, and stirring speed, on leaching of the copper oxide ore as well as the leaching kinetics were determined. The copper leaching rate increased with increasing reagent concentration and reaction temperature, and decreasing particle size. The leaching process was described by an interfacial mass transfer–solid-film diffusion kinetic model; this indicates that the reaction occurs on the particle surface and throughout the entire diffusion region, including pores and cracks. The empirical equation for the dissolution process was established to be 1/3ln(1−x)+[(1−x)^−1/3−1]=[1.94C^1.927P^1.322 exp(−3507.34/T)]t. The apparent activation energy was calculated to be 29.16 kJ/mol using this equation. Lactic acid can be employed as an organic leaching reagent to obtain a copper solution suitable for subsequent electrowinning. The data obtained in this study provides useful information for the leaching of other carbonate minerals of metals such as copper, zinc, and cobalt in organic acid systems.

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The accurate estimation of the pressure drop across a metal woven mesh is crucial for a filtration process. We therefore investigated the effect of the geometrical characteristics, namely, the weave type (plain weave and twilled weave), wire diameter, and number of meshes (number of wires per inch), on the flow resistivity. This was done by hybrid simulation using a combination of the lattice Boltzmann and immersed boundary methods (IB-LBM). It was found that, for a given aperture size of the woven mesh, the volume fraction increased with increasing wire diameter, with a consequent increase in the drag force. The volume fraction of the twilled weave mesh was bimodally distributed in the thickness direction, with the drag force at the second peak of the distribution lower than that at the first peak owing to the resistive loss at the first peak. This tendency became more pronounced with increasing Reynolds number. Based on these findings, we derived an equation for estimating the pressure drop, wherein the drag coefficient is expressed as a function of the volume fraction and Reynolds number. Based on the proposed equation, the relationship among the drag coefficient, volume fraction, and Reynolds number calculated from the experimentally determined pressure drop across the woven mesh was plotted as a single curve for each weave type. This enabled rational and highly accurate prediction of the pressure drop across the plain weave and twilled weave meshes.

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The present study investigates solid–liquid separation behaviors in centrifugal sedimentation for concentrated bidisperse colloidal suspensions containing polymethylmethacrylate (PMMA) particles of two different submicron sizes with equal densities, using an analytical centrifuge. The sedimentation coefficient for describing the settling rate of the interface separating the dispersion from clear liquid was determined from the sedimentation curve drawn based on the measurements of near-infrared light transmission. It was found that the sedimentation coefficient decreased with decreasing porosity and increasing ratio of the volume of small particles to volume of total particles, while it was little influenced by the initial height of suspension and the angular velocity of the rotor. A model was developed for describing the relation between the sedimentation coefficient and porosity in a suspension in the centrifugal sedimentation of a bidisperse suspension. In the low concentration region, the sedimentation coefficient was determined from the settling rate of small particles because small particles settled independently from large particles in the upper zone. In contrast, the sedimentation coefficient in the high concentration region was obtained based on the mean specific surface area size of small and large particles determined using the mixing ratio, since small and large particles settled collectively. In addition, the critical porosity determining the boundary between low and high concentration regions was well described by the model developed. The validity of the model was confirmed by comparing the calculations with experimental data.

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The particle mixer has a wide application in the chemical and petrochemical industries. In order to achieve adequate and homogeneous particle mixing, a new type of particle mixer was proposed by coupling a pre-mixing section and an internally circulating fluidized bed mixing section. The bed density and particle circulating velocity, as well as the cold and hot particle mixing degree in the mixer were investigated with an optical fiber probe and thermal particle tracer technology. Bed density in the internally circulating fluidized bed mixing section decreased with the increase of the superficial gas velocity in the draft tube, but changed slightly with the rise of the particle feeding mass flow rate. The radial evolution of the dimensionless bed density in the draft tube was approximative under different operating conditions. With the increase of the superficial gas velocity and particle feeding mass flow rate, both the particle circulating velocity and circulating mass flow rate increased, within 0.23 to 0.28 m/s, and between 90 kg/(m² s) and 10 kg/(m² s), respectively. The mixing performance was improved as the superficial gas velocity increased, while it changed only slightly with the rise of the particle feeding mass flow rate. The radial particle mixing was significant in the pre-mixing section where the mixing index could reach 0.7, and then in the draft tube where the mixing index could reach 0.95.

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Detection methods to broaden the measurable range of hydrogen peroxide (H₂O₂) concentrations are suggested for agricultural applications. Photovoltaic detection is based on the chemiluminescence (CL) of luminol with potassium ferricyanide as a catalyst. The use of potassium ferricyanide (non-biomaterial) enables the sensor to be stored for a long period at room temperature and can lower the manufacturing cost. In this study, the measurement range was broadened down to 3×10⁻⁵% by improving the stability and enhancing the sensitivity of the sensor. To improve the stability in the time domain, a low pass filter (LPF) was connected, reducing noise caused by ambient light. To enhance sensitivity, a reflective plate was employed to redirect diverging emitted light toward the photodiode. The highest possible detection level was also elevated up to 0.5% by preparing the mixture of luminol and catalysts (MLC) at high concentration. As a result, the performance index, IMR (Index of Measurable Range=maximum/minimum ratio of detectable concentration) of the system grew to over 16,000, which is about 16 times larger than previous results. All of the experimental results were confirmed to be in good agreement with calculated theoretical output voltages from chemiluminescence. The proposed device is intended to replace hazardous pesticides or antibiotics which have been used for agricultural applications.

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Composite particles dually functionalized with fluorescent and magnetic properties were prepared in a one pot synthesis in soap-free emulsion polymerization combined with heterocoagulation. Styrene monomer dissolving a fluorescent component, pyrene, was used in the emulsion polymerization; whereas, the magnetic nanoparticles surface-modified with a silane coupling agent possessing a double bond were continuously supplied to the polymerization system. The polymerization was conducted with an amphoteric initiator at a weakly basic pH suitable for heterocoagulation between the magnetic nanoparticles and the polystyrene particles formed in the polymerization. The magnetic nanoparticles could be incorporated into the inside of polystyrene particles by the double bonds reacting with polymer radicals formed in the polymerization, accompanied with absorption of pyrene by the polystyrene particles. The present method prepared highly monodisperse, submicrometer-sized composite particles with the dual functions of fluorescent and magnetic properties.

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In this study, we investigate the impact of polymer concentrations on the characteristics of duplex microcapsules prepared from an alginate derivative possessing phenolic hydroxyl moieties (Alg-Ph) via horseradish peroxidase- and catalase-catalyzed reactions. Membrane thicknesses increased from 17 to 40 µm with increasing Alg-Ph concentrations from 0.5 to 2.5% (w/v). In addition, the mechanical strength of microcapsules also increased with increasing Alg-Ph concentrations. Shrinking of microcapsules was observed in Dulbecco’s modified Eagle’s medium and simulated body fluid containing Ca²⁺ (13.1–29.2% reduction in diameter for a 12 d incubation). The diffusivities of dextran (4, 40 or 70 kDa) through a membrane of 2.5% (w/v) Alg-Ph microcapsules were almost the same as those of a 1.5% (w/v) calcium-alginate hydrogel. The results demonstrate that it is possible to tune the characteristics of microcapsule membranes obtained through co-enzymatic reactions to customize the particular applications.

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Polychlorinated biphenyls (PCBs) have been widely used as flame retardants, dielectric and heat transfer fluids, and plasticizers in industrial and household products. Due to their toxicity, carcinogenicity, and teratogenesis, these compounds are considered as persistent organic pollutants (POPs). In this study, 3,3′,4,4′-tetrachlorobiphenyl (PCB77) was used as a model compound to study the sorption kinetics and thermodynamics between PCBs and humic acid (HA). Dynamic test results showed that the sorption process was divided into a fast and a slow stage and that sorption equilibrium occurred after 12 h. Fitting results from the five adsorption kinetic models showed that a pseudo-second order kinetic model, Elovich model, and double-constants model accurately described the sorption process, and indicated that PCB-HA sorption is likely a complex mass transfer process comprised of liquid film diffusion, surface adsorption, and intraparticle diffusion. In addition, sorption–desorption isotherm fitting results showed that a Freundlich model accurately predicted the sorption-desorption process. Using the hysteresis index (HI), distinct desorption hysteresis was obtained (HI>1). Thermodynamic analysis results showed that the variation in the free energy of sorption was −6.01 kJ/mol at a temperature of 15°C. As this value was less than 40 kJ/mol, the interaction between PCB77 and HA was mainly comprised of physical sorption. PCB77-HA sorption was a spontaneous and exothermic process related to the combined action of Van der Waals attractions, hydrophobic bonding, dipole forces, and hydrogen bonding. Experimental results illustrated that HA exhibited a high sorption affinity for PCB77. The equilibrated sorption efficiency was determined to be 67.71% (solution to soil ratio of 400 : 1). Sorption was found to be irreversible, indicating that PCB77 can potentially accumulate in the soil organic matter of the topsoil layer. Findings from this study provide an improved understanding of the sorption kinetics and thermodynamics of PCBs associated with HA, as well as a theoretical foundation for the use of exogenous humic acid to control soil PCBs mobility and reduce the diffusion of PCBs in low SOM soils.

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In a difficult market environment, the development of technologically superior and novel products is an important corporate innovation strategy. Many studies have been conducted on methodologies for evaluating and filtering R&D themes, and many companies have put these methodologies into practice. The stage-gate methodology and “Product And Cycle-time Excellence (PACE)”, which typify these efforts, are excellent methods for filtering many R&D themes down to only the most promising. However, they risk overlooking promising themes only to have those themes disappear, and there are concerns that the administrative review may decrease researchers’ motivation. This study proposes a “boost-gate” methodology, which incorporates advice provided at gates to promote promising themes while boosting R&D activities. This methodology, implemented during R&D activity at one company, was shown to be effective. Using the number of patent applications as a metric for R&D results, this study confirmed an increase in important patents that lead to innovations. While there is no conclusive evidence at this time, the outcome still suggests that this methodology may be highly effective in promoting R&D. This paper introduces the way in which this methodology should be adopted by businesses. It is hoped that this methodology will be applied to R&D activities at major corporations.

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