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Volume 35, Issue 6
Displaying 1-15 of 15 articles from this issue
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Transport Phenomena, Fluid Mechanics and Mixing
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Csaba Suri, Katsuhide Takenaka, Yoshihiro Kojima, Kiyohito KoyamaArticle type: Research Papers
Subject area: Transport Phenomena, Fluid Mechanics and Mixing
2002 Volume 35 Issue 6 Pages 497-502
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSThe acoustic mixer presented in this paper is a cylindrical vessel placed into an acoustic field. Ultrasound was generated in a water vessel by transducers placed outside of the cylinder either perpendicularly or parallel to its axis. The system was used to circulate the water on an axis of the vessel, which we called “spin”, similar to traditional mixing methods and to generate three-dimensional flow patterns. To visualize the process, iodine solution with sodium thiosulfate was mixed and the degree of the mixing was measured using a laser-photodiode system. The optimal mixer configurations have been determined for a thin walled cylinder surrounded by transducers. Best results were obtained when two transducers were placed at different heights of the glass vessel and at 90 degrees with each other with generation of streaming in the same direction.View full abstractDownload PDF (5587K) -
Sontaya Krichnavaruk, Prasert PavasantArticle type: Research Papers
Subject area: Transport Phenomena, Fluid Mechanics and Mixing
2002 Volume 35 Issue 6 Pages 533-539
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSThis work investigated the effects of perforated plates on the performance of an airlift contactor. The result showed that the rate of gas-liquid mass transfer in the airlift contactor with perforated plates was significantly greater than those found in a conventional airlift contactor and in a bubble column. This was because the perforated plates induced resistance to fluid flows which lengthened the residence time of gas bubbles in the riser. This in turn gave a greater local gas holdup and also a higher rate of mass transfer between gas and liquid. On the other hand, perforated plates reduced the liquid velocity in the system which was found to negatively influence the gas-liquid mass transfer rate. However, in most cases, the effect of the increase in riser gas holdup on the gas-liquid mass transfer rate overwhelmed that from the low liquid velocity, and the resulting overall volumetric mass transfer coefficient was found to increase in the system with perforated plates. In this work, it was reported that there existed the optimal hole size and the optimal number of holes which gave the highest gas-liquid mass transfer rate. The number of perforated plates in the ALC was also examined and the investigation revealed that there was a maximum number of plates that could be inserted in the ALC above which no further enhancement of overall volumetric mass transfer rate was obtained.View full abstractDownload PDF (1169K)
Catalysis, Kinetics and Reactor Design
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Worapon Kiatkittipong, Suttichai Assabumrungrat, Piyasan Praserthdam, ...Article type: Research Papers
Subject area: Catalysis, Kinetics and Reactor Design
2002 Volume 35 Issue 6 Pages 547-556
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSA pervaporation membrane reactor for the synthesis of ethyl tert-butyl ether (ETBE) from a liquid phase reaction between ethanol (EtOH) and tert-butyl alcohol (TBA) was investigated. Supported β-zeolite and a polyvinyl alcohol (PVA) membrane were used as a catalyst and a membrane in the reactor, respectively. The permeation studies of an H2O-EtOH binary system revealed that the membrane worked effectively for H2O removal at the mixtures containing H2O content lower than 62 mol%. The permeation studies of quaternary mixtures (H2O-EtOH-TBA-ETBE) were performed at 3 temperature levels of 323, 333 and 343 K. It was found that the membrane was preferentially permeable to H2O. The permeability coefficients were correlated with the Arrhenius equation. In the pervaporation membrane reactor studies, both experiment and simulation were carried out. An activity-based model was developed to investigate the performance of the pervaporation membrane reactor using parameters obtained from other independent experiments. The simulation results agreed well with experimental results. It was observed that the ratio of the initial mole of EtOH to TBA (λ), the ratio of the membrane area to the initial mole of TBA (δ), the ratio of the amount of catalyst to the initial mole of TBA (ø), the operating temperature and the membrane selectivity played important roles on the reactor performance. The analysis of the operating temperature showed an optimum yield due to the competing effect of the rate of reaction and the rate of reactant losses.View full abstractDownload PDF (670K) -
Hideo Tajima, Kei Tabata, Takashi Niitsu, Hakuai InoueArticle type: Research Papers
Subject area: Catalysis, Kinetics and Reactor Design
2002 Volume 35 Issue 6 Pages 564-568
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSWe investigated the formose reaction using a zeolite impregnated with thiazolium catalyst. The zeolite catalyzed the formose reaction in an organic solvent and then the reaction rate was pseudo first order with respect to the formaldehyde concentration. The main products were DHA, erythrulose, and 4-hydroxymethyl-2-pentulose. The selectivity of the branched sugar was increased by the choice of conditions. For the reuse of the catalytic zeolite, washing with water was one of the important factors. These results are important for sugar synthesis processes from formaldehyde in one step.View full abstractDownload PDF (321K)
Separations
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Eliana L. Ligero, Teresa M. K. RavagnaniArticle type: Research Papers
Subject area: Separations
2002 Volume 35 Issue 6 Pages 557-563
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSOne technique that has been largely used in the production of anhydrous ethanol is the azeotropic distillation with benzene, whose carcinogenic properties are well known. The present work reports on the extractive distillation by salt effect using a soluble potassium acetate salt, which is an alternative ecologically viable process to dehydrate an ethanol-water mixture. Besides producing an ethanol free of separating agent, it allows a reduction in energy requirement. An important factor in this process is the salt recovery to be reused in the distillation column, which is fundamental to the economical viability of the process. In this work, the potassium acetate salt is completely recovered in a spray dryer. The process simulation results showed that the proposed process presented a lower energy requirement than conventional processes, which use a liquid separation agent, and the potassium acetate proved to be an appropriate agent to replace benzene.View full abstractDownload PDF (342K) -
Maiko Yamanobe, Hiroshi Takiyama, Masakuni MatsuokaArticle type: Research Papers
Subject area: Separations
2002 Volume 35 Issue 6 Pages 569-573
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSFT-IR measurements of solutions of organic compounds, which have several polymorphs, were carried out to discuss the effects of solvents on polymorphic crystallization. DL-Methionine (DL-Met) and bisphenol A (BPA) were used as model compounds. For DL-Met, characteristic peaks of IR spectra of solutions after reaction crystallization with various acids agreed with those of obtained crystals. The difference of IR spectra between solutions indicates that molecular conformations of DL-Met have already changed in the solutions before crystallization and were affected by the acids used for the reaction crystallizations. In the case of BPA, IR spectra of solutions with various solvents were measured to examine the effects of solvents on polymorphic crystallization. Solutions with benzene and ethylbenzene showed similar characteristic peaks each other and form II crystals precipitated from benzene solutions while amorphous solid was obtained from ethylbenzene solutions. Form I crystallized from other solutions without characteristic peaks.
From these results, FT-IR measurement of solutions was concluded to be a useful analytical method to examine the effect of solvents on selective crystallization of polymorphs.View full abstractDownload PDF (2797K) -
Eiji Kamio, Kazuo KondoArticle type: Research Papers
Subject area: Separations
2002 Volume 35 Issue 6 Pages 574-581
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSIn this study, we measured the extraction equilibria of lanthanoids with microcapsules containing acidic organophosphorus compound as an extractant and discuss their mutual separation by using a column packed with the microcapsules. The extraction equilibria of lanthanoids into the microcapsules containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA) were elucidated and the extraction equilibrium constants were calculated by slope-analysis method. It was suggested that the lanthanoid ions are extracted in the microcapsules in a high loading state.
Furthermore, the adsorption behavior of lanthanoids into the column packed with the microcapsules containing EHPNA was observed. It was found that adsorption and elution of lanthanoids are briefly achieved by selecting pH of the feed aqueous solution. However, it was impossible to separate them only in adsorption or elution operation.
So, the mutual separation of lanthanoids was investigated using the adsorption column connected to the development column containing microcapsules. By selecting pH of the eluent, each metal was separated mutually in more than 95% of purity. The metal ions in the eluent from the development column could be concentrated by treating it with a column packed with the microcapsules containing di(2-ethylhexyl)phosphoric acid (D2EHPA).
Considering these information, it will be possible to design a continuous extracting, separating and concentrating reactor of lanthanoids using a column packed with the microcapsules.View full abstractDownload PDF (1518K) -
Chu-Yuan Chen, Chun-I Lin, Hsi-Kuei ChenArticle type: Short Communications
Subject area: Separations
2002 Volume 35 Issue 6 Pages 587-589
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSSoy oil was bleached with different rice hull ashes and clays. UV-vis absorbance spectra of bleached oils were presented. The spectra indicated that the bleaching with rice hull ashes or clays were of physical adsorption. It also revealed that the bleaching with rice hulls ashed in nitrogen stream was generally more efficient than those with rice hulls ashed in air stream. Acid activated ashes showed higher bleaching capability than unactivated ones. Moreover, unwashed activated ashes were found to be more effective in bleaching than washed ones.View full abstractDownload PDF (337K)
Particle Technology and Fluidization
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Chien-Song Chyang, Yen-Chin LinArticle type: Research Papers
Subject area: Particle Technology and Fluidization
2002 Volume 35 Issue 6 Pages 503-512
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSAn innovative swirling fluidizing pattern generated by a multi-horizontal nozzle distributor was developed to minimize the axial momentum of fluidizing air and to provide momentum in both the radial and tangential directions. Experiments in pressure fluctuations and fines elutriation in the fluidized-bed system were conducted in 0.29-m I.D. and 0.19-m I.D. fluidized-bed cold models respectively to investigate the influence of the fluidizing pattern. The performances of the “swirling fluidizing pattern” and the conventional “axial fluidizing pattern” caused by a perforated plate were compared. In pressure fluctuation experiments, the pressure signals within the bed were converted into the frequency spectra using a Fast Fourier Transform (FFT) to proceed the spectral analysis. Effects of superficial air velocity, static bed height and distributor open-area ratio were taken into account. At a low nozzle air-discharge velocity, a stable concentration of fines within the bed would be attained. The first-order elutriation rate equation cannot describe the elutriation behavior of fines under a swirling fluidizing pattern, except at an extremely high air-discharge velocity. The swirling fluidizing pattern proved to produce a remarkable improvement in both the fluidization quality and elutriation reduction.View full abstractDownload PDF (669K) -
Rome-Ming Wu, Gian-Wei Tsou, Pei-Shan Yen, Duu-Jong Lee, Xiao-Feng Pen ...Article type: Research Papers
Subject area: Particle Technology and Fluidization
2002 Volume 35 Issue 6 Pages 540-546
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSWe experimentally justified the validity of the basic assumption made in most floc models: there exists a strong advection flow through the floc. A swarm of bubbles were generated and released from the bottom of a water pool and rose at the same falling plane of the floc. Information regarding the fluid field, the capture ratio, and the extent of the advection flow were obtained by tracking the interactions of the floc and the bubbles. The advection flow through the floc is found unexceptionable in all tests. The polyelectrolyte flocculation would markedly reduce the extent of advection flow. The floc permeability was estimated based on comparison between experimental findings and the numerical simulations.View full abstractDownload PDF (3739K) -
Boris Golman, Zengo Ohashi, Kunio Shinohara, Shin-Ichiro Fujita, Masah ...Article type: Short Communications
Subject area: Particle Technology and Fluidization
2002 Volume 35 Issue 6 Pages 590-594
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSThe adsorption characteristics were investigated with differently sized agglomerates of zeolite particles for moving-bed applications. As a result, the saturation amount of NO gas adsorbed on the agglomerates was almost the same as that of the primary particles, and thus the negligible influence of binder was confirmed. Relying on the measured adsorption rate for the agglomerates of different sizes, the region of favorable agglomerate size for the moving-bed application was identified as 0.8 to 1.3 × 10–3 m where the adsorption rate is still appreciable and the agglomerates are large enough to ensure smooth flow inside the apparatus. As an example of the application of the proved adsorption rate equation, the influence of operational parameters was theoretically demonstrated on the performance of a co-current moving-bed adsorber. It was found that, in order to attain the significant gas cleaning efficiency during the treatment of a large volume of gas, the solids velocity should be increased and the adsorbent recycle system should be used to improve the utilization of adsorbent.View full abstractDownload PDF (429K)
Biochemical, Food and Medical Engineering
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Masahiro Yasuda, Taiki Imakiire, Hirofumi Yoneda, Masayuki Okamoto, Hi ...Article type: Research Papers
Subject area: Biochemical, Food and Medical Engineering
2002 Volume 35 Issue 6 Pages 519-526
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSTo develop a novel support of enzymes for use in the enzymatic reactions in nonaqueous solutions, amphiphilic polymer particles which have 2-[p-(1, 1, 3, 3-tetramethyl-butyl)phenoxy-polyethoxy]ethyl groups (tert-C8ΦEn groups; n is the mean number of the ethylene oxide units) were synthesized by the seed copolymerization of styrene, divinylbenzene, and 2-[p-(1, 1, 3, 3-tetramethyl-butyl)phenoxy-polyethoxy]ethyl methacrylate (MAX-n). In seed polymerization, the mean number n of the tert-C8ΦEn group did not affect the monomer conversions and the amount of MAX-n introduced into the particles. Using Rhizopus delemar lipase as a model enzyme, the enzyme immobilization on the amphiphilic polymer particles was investigated. The specific hydrolytic activity of the immobilized lipase prepared with the amphiphilic polymer particles was higher than that of native lipase. When the amphiphilic particles synthesized using MAX-15.9 were used to immobilize lipase, the amount of lipase immobilized and the hydrolytic activity and the transesterification activity of the immobilized lipase were the highest. However, the organic solvent stability of the immobilized lipase prepared with the amphiphilic particles synthesized using MAX-4.39 was the highest.View full abstractDownload PDF (1143K)
Safety, Environment and Energy
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Kang Ryu, Eun Kyu LeeArticle type: Research Papers
Subject area: Safety, Environment and Energy
2002 Volume 35 Issue 6 Pages 527-532
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSRapid screening method using color reaction was developed to quantitatively evaluate the lignin peroxidase (LiP) activity. For 2, 4-dichlorophenol (DCP) degradation activity, this method correlated well with the HPLC method. The lignin peroxidase H2 gene was isolated from Phanerochaete chrysosporium, a white-rot fungus. The molecular weight of the recombinant LiP was ca. 38 kDa, which corresponded to the predicted mature LiP H2 gene. We performed cloning into pYD vector for yeast cell surface display of the gene. The surface expression was checked by the rapid, colorimetric screening method. The supernatant did not change the color, but the washed yeast cells changed the color from white to red, which confirmed the enzymes were located on the cell surface. Five colonies expressing the LiP H2 gene at high levels were selected. The average amount of 2, 4-DCP degradation was about 23%. It was approximately 63% degradation level of the LiP from the wild type fungus. This screening and selection protocol is being applied to the DNA shuffling effort to screen LiPs with improved functionality and stability.View full abstractDownload PDF (5647K) -
Byung-Dae Lee, Satoshi Nakai, Masaaki HosomiArticle type: Short Communications
Subject area: Safety, Environment and Energy
2002 Volume 35 Issue 6 Pages 582-586
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSAs a means to remediate soil contaminated by polycyclic aromatic hydrocarbons (PAHs), a method is described for effective pretreatment of soil highly contaminated with PAH indicators benzo(a)pyrene (BAP), benzo(b)fluoranthene (BBFT), benzo(k)fluoranthene (BKFT), and dibenz(a, h)anthracene (DIB) at initial concentrations of 62.1, 105.3, 29.0, and 44.2 mg·kg–1 soil, respectively. Fenton oxidation is applied in which ethanol is added to increase removal of PAHs. Reported are the optimum amounts of ethanol, Fe2+, and H2O2 needed to achieve maximum removal efficiency. Under these optimal conditions, we obtained the following removal efficiencies: BAP, 98.6%; BBFT, 72.9%; BKFT, 97.7%; and DIB, 99.5%. Resultant concentrations of BAP and BKFT satisfied the Canadian soil standard for residential areas (<1 mg·kg–1). It is considered that the proposed treatment method can effectively remove PAHs from contaminated soil prior to disposal at industrial waste sites.View full abstractDownload PDF (404K)
General Research and Others
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Improvement of Industrial Properties of Sodium Perborate Tetrahydrate Using Anionic PolyelectrolytesSibel Titiz-Sargut, G. Yildiz Yuksel, A. Nusret BulutcuArticle type: Research Papers
Subject area: General Research and Othres
2002 Volume 35 Issue 6 Pages 513-518
Published: 2002
Released on J-STAGE: August 12, 2002
JOURNAL RESTRICTED ACCESSThe effect of anionic polyelectrolytes on the crystallization kinetics and some important industrial properties of sodium perborate tetrahydrate, such as particle size, bulk density and degree of attrition were studied by using an MSMPR type laboratory crystallizer. The anionic polyelectrolytes having similar chemical structures but different charge density were used in the experiments. The experimental results showed that the anionic polyelectrolyte, which has 30% degree of anionicity does not affect the growth and nucleation rates of sodium perborate tetrahydrate compared with the sodium perborate tetrahydrate crystallization in the absence of polyelectrolyte. Decreasing the nucleation rate and increasing the growth rate in the presence of the anionic polyelectrolytes having low anionicity (2 and 10%) and high anionicity (50%) caused an increase of the average particle size and the bulk density and the decrease of the degree of attrition of sodium perborate tetrahydrate crystals. It was seen that the anionic polyelectrolytes having high molecular weight affected the sodium perborate crystallization more than the anionic polyelectrolytes having low molecular weight.View full abstractDownload PDF (10953K)
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