Editor-in-Chief
Takao Tsukada (Tohoku University)

Associate (Editor-in-Cheifs)
Manabu Shimada (Hiroshima University)
Masahiro Shishido (Yamagata University)

Editors
Ryuichi Egashira (Tokyo Institute of Technology)
Jun Fukai (Kyushu University)
Choji Fukuhara (Shizuoka University)
Toshitaka Funazukuri (Chuo University)
Takayuki Hirai (Osaka University)
Jun-ichi Horiuchi (Kitami Institute of Technology)
Eiji Iritani (Nagoya University)
Yoshinori Itaya (Gifu University)
Noriho Kamiya (Kyushu University)
In-Beum Lee (Pohang University of Science and Technology (POSTEC))
Kouji Maeda (University of Hyogo)
Hideyuki Matsumoto (Tokyo Institute of Technology)
Nobuyoshi Nakagawa (Gunma University)
Masaru Noda (Fukuoka University)
Hiroyasu Ogino (Osaka Prefecture University)
Mitsuhiro Ohta (The University of Tokushima)
Eika W. Qian (Tokyo University of Agriculture and Technology)
Yuji Sakai (Kogakuin University)
Noriaki Sano (Kyoto University)
Naomi Shibasaki-Kitakawa (Tohoku University)
Ken-Ichiro Sotowa (The University of Tokushima)
Hiroshi Suzuki (Kobe University)
Nobuhide Takahashi (Shinshu University)
Shigeki Takishima (Hiroshima University)
Yoshifumi Tsuge (Kyushu University)
Tomoya Tsuji (Nihon University)
Da-Ming Wang (National Taiwan University)
Takuji Yamamoto (University of Hyogo)
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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During the recovery of phosphorus from the powder collected in a bag filter during the recycling of used fluorescence tubes (bag-powder), the batch method with aqueous HNO₃ was used to examine the elution behavior of aqueous phosphate contained in the bag-powder. The main components of the bag-powder included Ca²⁺, PO₄³⁻ and Y³⁺ along with Si⁴⁺, Sr²⁺ and lanthanide cations such as La³⁺ and Ce⁴⁺. Therefore, it seemed possible that, with the selective dissolution of Ca²⁺ and PO₄³⁻ from the bag-powder, these lanthanide cations in the residue could be enriched. With the batch method, most of the phosphate in the bag-powder was dissolved within 0.2 min using 1.0 mol/L HNO₃. The dissolution behavior of calcium cation was similar to that of the phosphate. In contrast, the dissolution of yttrium, the content of which was the highest among the lanthanide cations in the bag-powder, was increased with the dissolution times, reaching complete dissolution after 24 h. The Sr²⁺, La³⁺ and Si⁴⁺ in the bag-powder, however, did not dissolve under the same conditions. Although Ca²⁺, PO₄³⁻ and Y³⁺ were the main components in the nitric acid extract, Y³⁺ was separated as YPO₄ at pH=4.0, while Ca²⁺ and PO₄³⁻ were separated as calcium phosphates at pH=7.0. These results revealed that the separation of calcium phosphates, YPO₄ and some residue was possible, and resulted in the enrichment of lanthanide cations along with the recovery of phosphorus from the bag-powder. Using the present technique, 91% of the P in the bag-powder was recovered.

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Critical temperatures and critical pressures are fundamental properties used widely for discussing the corresponding-state principle. The critical constants are collected in reference books, but at present, experimental critical constant data are rarely measured for new compounds. On the other hand, Antoine constants for new compounds have been determined from vapor pressure data. In this paper, equations for evaluating critical temperature and critical pressure from molecular descriptors are obtained using the polynomial expansion method. The molecular descriptors used are Antoine constants, van der Waals volume and ovality. A genetic algorithm has been used to determine the fit parameters in the polynomial expansion equation. The values obtained using these new equations are more accurate than those obtained using the Joback method.

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A new statistical parameter was defined in order to determine the range of applicability of the mixing length concept in two bubble columns. Gas holdup time series (60,000 points) were measured in two bubble columns (0.15 and 0.4 m in i.d.) by a conductivity wire-mesh sensors. The new statistical parameter Φ was defined as the ratio of the mean value of the signal to three times the average absolute deviation (3AAD) and it was correlated to the mixing length. It was found that this new correlation was not valid in all hydrodynamic regimes. It is applicable only in the transition flow regime. Such a clarification has not been provided in the literature so far. In the narrow bubble column, the results were also confirmed on the basis of the Kolmogorov entropy and another statistical parameter. The new parameter Φ was also used for flow regime identification. In the narrow bubble column, the first transition velocity U_trans was identified at 0.034 m/s; whereas, the second U_trans occurred at 0.112 m/s. In the large bubble column, the two U_trans values were identified at 0.045 and 0.101 m/s, respectively.

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This paper describes three findings. The first is a method for producing colloidal solutions of quantum dot (QD) nanoparticles with silica shells (QD/SiO₂). QD nanoparticles averaging 10.3±2.1 nm in size were coated with silica via a sol–gel reaction with tetraethyl orthosilicate using NaOH as a catalyst. The QD/SiO₂ particle size could be varied by varying the QD concentration. The average particle sizes were 19.1±3.0 (S-QD/SiO₂) and 47.0±6.1 nm (L-QD/SiO₂) for QD concentrations of 6.4×10⁻⁹ M (4.6×10¹¹ particles/L) and 6.4×10⁻¹⁰ M (4.6×10¹⁰ particles/L), respectively. The second finding is a method to modify the particle surface with poly(ethylene glycol), which is called PEGylation (QD/SiO₂/PEG). S-QD/SiO₂ and L-QD/SiO₂ were PEGylated using methoxy polyethylene glycol silane (S-QD/SiO₂/PEG and L-QD/SiO₂/PEG, respectively). The third finding is an in-vivo fluorescence imaging technique using the QD/SiO₂/PEG particle colloid solutions. Both QD/SiO₂/PEG particle colloid solutions fluoresced with intensities comparable with that of the QD colloid solution. Mouse tissues could be imaged by injecting the QD/SiO₂/PEG colloid solution into them and measuring the emitted fluorescence intensity. The L-QD/SiO₂/PEG particles did not form aggregates in blood, which allowed the particles to reach the tissues more efficiently than the S-QD/SiO₂/PEG particles.

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In this paper, a novel multi-stage loop extraction column (MSLEC) is proposed based on the principles of a jet loop contactor and droplet-film alternate flow. The experiments under different U_c and U_d were carried out to investigate the flow structure, hydrodynamic performance and mass transfer efficiency of the MSLEC in liquid–liquid extraction. The results showed that the flow structure in the MSLEC formed the alternating droplet-film flow of the dispersed phase. Meanwhile, the plug-flow for the dispersed phase and the circulation-flow for the continuous phase achieved parallel flow. The hydrodynamics and mass transfer efficiency of extraction tower using Super Mini Rings (SMREC) were measured under the same conditions as a control. The hydrodynamic performance in the MSLEC was enhanced by 52% and the mass transfer efficiency was enhanced by 24% on average.

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Batch and column adsorption of divalent cadmium ions from aqueous solution using oxidized activated carbon (OAC) was investigated. Commercially available bead-shaped activated carbon (BAC) was oxidized with ammonium persulfate, and Cd(II) adsorption experiments were performed in batch and flow systems. The total amount of Cd(II) adsorbed in the flow system was 1.7 mmol/g, which was asymptotically equal to the maximum amount adsorbed in the batch system. Regeneration of the adsorbent was evaluated via Cd(II) desorption from OAC using 0.1 M nitric acid. The total Cd(II) desorbed was approximately 1.9 mmol/g, which was nearly equivalent to the total Cd(II) adsorbed in the flow system. The amount of Cd(II) adsorbed using regenerated OAC in the 2nd-cycle was not significantly different from that adsorbed in the 1st-cycle. These results imply that OAC is prospectively reusable for Cd(II) adsorption applications.

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Linear alkylbenzene sulfonate (LAS) is an important industrial anionic surfactant. It is usually made by sulfonation of linear alkylbenzene (LAB) in a falling film reactor with sulfur trioxide gas. In this paper, LAS was prepared in a rotating packed bed (RPB) with dilute liquid sulfur trioxide, followed by aging treatment inside the RPB. The influences of the rotating speed, the sulfonating agent concentration, the SO₃/LAB molar ratio, the sulfonation temperature in the sulfonation step and the aging residence time as well as the different reactor design on the aging step onto the sulfonation process were all examined. In the sulfonation step, the LAS concentration reached 91.75% at a lower temperature owing to the intensified micro-mixing performance of the RPB. In the aging step, the RPB can significantly shorten the aging time. The RPB shows great potential for the industrial application of sulfonation.

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Although previous researchers have found that FSM-16 (#16 Folded Sheet Mesoporous material) doped with chromium and related Cr-doped silica catalysts has shown great activity for the oxidative dehydrogenation of isobutane to isobutene, information on the nature of these catalysts is insufficient. For this study, three types of Cr-doped silica catalysts were prepared by applying the template ion exchange method. CrO_x/FSM-16 and CrO_x/SiO₂ were used as references. These catalysts were used for oxidative dehydrogenation, which was then characterized via various techniques. The most active catalyst was Cr-doped silica, which did not have the hexagonal structure that is characteristic of mesoporous FSM-16. Various characterizations showed that the catalytic activity of the Cr-species, stemmed from a weak acidic nature and a redox nature that originated from the combination of silicate and a Cr cation, as opposed to the hexagonal structure and strong acidic nature of FSM-16.

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Photocatalytic hydrogenation of nitroaromatics was carried out with silica-supported iron oxides (FeO_x/SiO₂) as catalysts and hydrazine monohydrate as a reductant. Photoirradiation of the catalysts at λ>300 nm promotes hydrogenation of nitroaromatics to the corresponding anilines with more than 90% selectivity. The FeO_x/SiO₂ catalysts with lower Fe loadings possess monomeric Fe^III species behaving as the active sites and exhibit higher photocatalytic activity and aniline selectivity. Electron spin resonance (ESR) analysis revealed that photoexcitation of the hydrazine-adsorbed monomeric Fe^III species produces Fe^II species by the reduction with hydrazine. The Fe^II species promote the reduction of nitroaromatics to anilines, along with the Fe^II→Fe^III oxidation.

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