JOURNAL OF CHEMICAL ENGINEERING OF JAPAN
Online ISSN : 1881-1299
Print ISSN : 0021-9592
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Volume 29, Issue 2
Displaying 1-36 of 36 articles from this issue
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Original Papers
  • Measurement of Particle Flow Behavior in a Pilot-Plant Multi-Solid Fluidized Bed Combustor by Using Suction Probe Technique
    Kyu Kyu Win, Hitoki Matsuda, Masanobu Hasatani, Wojciech Nowak, Matthi ...
    1996 Volume 29 Issue 2 Pages 205-210
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.205
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    Measurements of the solid mass fluxes and particle size distributions were made by using a suction probe in a pilot-plant Multi-Solid Fluidized Bed (MSFB) combustor. The focus of this paper is to understand the flow structure in a MSFB under combustion conditions and the effect of geometrical configuration of the combustion chamber on the internal flow structure and particle size distributions. This paper also presents the applicability of suction probe technique for measuring the particle flow behavior in a hot model MSFB. The measurement results on the radial solid mass fluxes and particle size distribution show that not only the radial solid mass fluxes but also the mean diameter of particle and radial distribution of coarse particles (i.e. large coal particles (>1 mm)) depend on the geometrical configuration of the combustion chamber. The suction probe technique is found to be successful in measuring solid mass fluxes and particle flow behavior under combustion conditions.
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  • Hydrodynamic Behavior of a Binary Solids Fluidized Bed
    D. Bai, Y. Masuda, N. Nakagawa, K. Kato
    1996 Volume 29 Issue 2 Pages 211-216
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.211
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    This paper presents a study on the hydrodynamic behavior of a fluidized bed containing mixtures of solids of different sizes and densities. The transition velocity from bubbling to turbulent fluidization and solids holdup of the dense bed in different fluidization regimes were experimentally determined. The onset velocity to turbulent fluidization was found to increase with increasing fraction of coarse solids. Solids holdups changed differently with gas velocity and fraction of coarse particles in bubbling and turbulent fluidization regimes. As a quantitative measure for describing the complexity or the self-affine property of the time series signals, a fractal analysis was introduced and related to the hydrodynamics of the fluidized beds. A correlation to predict the transition velocity of a binary solids fluidized bed was also developed in this paper.
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  • Measurement of Infinite Dilution Activity Coefficient and Application of Modified ASOG Model for Solvent-Polymer Systems
    Bong Goo Choi, Joong So Choi, Katsumi Tochigi, Kazuo Kojima
    1996 Volume 29 Issue 2 Pages 217-222
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.217
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    A gas chromatographic method was used in order to measure vapor-liquid equilibria for solvent (1)-polymer (2) systems in which the polymers were polystyrene, poly(a-methyl) styrene and the solvents were benzene, toluene, cyclohexane, methylisobutylketone, ethylacetate, and vinylacetate. The activity coefficients of solvents for solvent (1)-polymer (2) systems were measured at infinite dilution and the modified ASOG (Analytical Solution of Group) model was suggested to describe vapor-liquid equilibria of those systems within a range of temperatures 423.15 K through 498.15 K. The model consists of the original ASOG and the free volume term. An external degree of freedom in the free volume term empirically became to a C1 = α + β/T as a function of temperature. Each term in the modified ASOG model is based on the weight fraction. The external degree of freedom in the model was estimated by experimental data within a range of temperatures. As a result of doing it, the infinite dilution activity coefficients calculated were agreed with the experimental data within an error of 0.1%.
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  • A Kinetic Study on the Formation of LaNi5–xAlx, MmNi4.5Al0.5 Hydrides
    Xianglong Wang, Seijirau Suda
    1996 Volume 29 Issue 2 Pages 223-228
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.223
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    The hydriging reaction kinetics of LaNi4.7Al0.3 under isothermal conditions were studied in detail using a double-walled reactor which possessed high heat conductivity. The reaction characteristics in the α+β phase region were discussed from the viewpoint of rate-controlling steps.
    It was found that several rate-controlling steps were involved during hydriding reactions from the α to the β phase regions and the rate-controlling step changed with the change of phase regions. For the hydriding reaction in the α+β phase region, the rate-controlling step was found to be the phase transformation process at the interface between the α and the β phases.
    The hydriding reaction kinetics of other rare earth-nickel based alloys, LaNi5–xAlx (x = 0, 0.1, 0.2) and MmNi4.5Al0.5 (Mm: mischmetal), were determined in the same way, and similar results were obtained.
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  • Effects of Pulsating Magnetic Fields on Electrolytic Mass Transfer around Cylindrical Cathodes
    Shigeru Mori, Mikio Kumita, Masashi Takeuchi, Akira Tanimoto
    1996 Volume 29 Issue 2 Pages 229-234
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.229
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    The influence of pulsating magnetic fields on mass transfer was studied experimentally in the electroreduction of ferrocyanide ions around an inclined cylindrical cathode under diffusion-controlled conditions. The mass transfer rate is increased by applying the pulsating magnetic field as well as the static one. The time-averaged enhancement of the mass transfer rate is dependent markedly on duty cycle (ON-time ratio), peak magnetic flux density of the applied pulsating magnetic fields in a range of 20 to 200 mHz, and slightly on its frequency. The mass transfer coefficient was correlated well by two types of non-dimensional regression equations with and without a duty-cycle factor, by using the “magneto-diffusion factor” to express the contribution of the applied magnetic flux density.
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  • Fundamentals on Combustion and Gasification Behavior of Coal Particle Trapped on Molten Slag Layer
    Reiji Noda, Ichiro Naruse, Kazutomo Ohtake
    1996 Volume 29 Issue 2 Pages 235-241
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.235
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    In order to develop a slagging coal gasifier and an Integral Gasification Combined Cycle (IGCC), fundamental behavior of combustion/gasification of a coal particle trapped on the molten slag layer was studied by using a laboratory scale batch reactor. Air and CO2 were used as reactants to burn and gasify the coal particle, respectively. The experiments were carried out by dropping a single coal particle onto the molten slag layer. The producted gas concentrations and the surface temperatures of coal particle and slag layer were continuously measured by gas analyzers and a two-dimensional two-color pyrometer, respectively. The indicated results by the analyzers were deconvoluted to evaluate the true time history of concentration change since the changing rate of concentration corresponded to the time delay of the analyzers comparably. In order to observe the change of particle structure, the reacting particle was quenched by injecting N2 gas. After that, the surface and internal structures were observed by an SEM and an optical microscope, respectively.
    As a result, the accuracy of adopted temperature measuring method was found to be within ±40 K. Under the combustion condition the particle temperature of coal exceeded that of the slag layer. Under the gasification condition, on the other hand, the reverse tendency was observed. The molten slag layer decelerated the reaction rate, especially under the gasification condition, since the melting points of ash and coal particle itself fell down due to the reducing condition occurring around/in the coal particle.
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  • Drying Rate and Shrinkage Effect Interaction during Freeze Drying in an Adsorbent Medium
    José I. Lombraña , Marí ...
    1996 Volume 29 Issue 2 Pages 242-250
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.242
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    A Kinetic analysis of freeze drying by immersion in an adsorbent fluidised bed process has been carried out in this paper. The process is described based on a uniformly retreating ice front model in spherical geometry. The model needs to know both temperature and pressure driving forces, correlated as a function of water content.
    The influence exerted by operational conditions on the heat and mass coefficients has been studied. Transport coefficients are correlated as a function of the operating conditions to obtain equations that can be used for predicting purposes in fluid bed freeze drying. Kinetic aspects are related to quality indicators determined through shrinkage of product to select the most adequate operating conditions.
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  • Effect of Particle Size and Heating Temperature of Ceramic Powders on Antibacterial Activity of Their Slurries
    Jun Sawai, Hideo Igarashi, Atsushi Hashimoto, Takao Kokugan, Masaru Sh ...
    1996 Volume 29 Issue 2 Pages 251-256
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.251
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    The effects of particlesize and heating temperature of magnesium oxide (MgO), calcium oxide (CaO), and zinc oxide (ZnO) powders on the antibacterial activities of their slurries were studied by the conductance method. An increase in particle size of the powders reduced their antibacterial activity. The variation of activity against Staphylococcus aureus was smaller than that against Escherichia coli, Salmonella typhimurium, and Bacillus subtilis. This difference depended on the shape of the bacteria, but not their character, such as the structure of the cell walls. The antibacterial activity of these powder slurries decreased with an increase in heating temperature of the powders. For the ZnO powder slurry, the decrease in antibacterial activity were much larger than those of the MgO and CaO powder slurries. It was suggested that these decreases in the antibacterial activity was concerned with stabilization of the surface of the powders heated at high temperature.
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  • Dry Coal Cleaning Process for High-Quality Coal
    Zennosuke Tanaka, Hiroshi Sato, Masayuki Kawai, Kiyonobu Okada, Teruo ...
    1996 Volume 29 Issue 2 Pages 257-263
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.257
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    In this study, a dry coal cleaning process was developed for cleaning fine and ultrafine coal to obtain a high-quality coal. The design criterion was determined, and the operational conditions were formulated. In addition, the deash and desulfurization performances for this process were examined.
    A classification column was used for fine coal down to 45 microns, and a centrifugal classifier was also used for cleaning ultrafine coal particles of less than 38 microns. Some species of coal were cleaned into a high-quality coal that contained less than 1% ash content by the fluidized classification column. For finely ground coal, ash was concentrated in the ultrafine coal fraction. Pyritic sulfur was also removed to some extent in this process for fine coal particles. For most coals, the ash content could be reduced by half and the thermal recovery was up to 90%. The method of comminution was also found to play an important role in the coal cleaning process.
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  • Growth Mechanism of Cadmium Sulfide Ultrafine Particles in Water-in-Oil Microemulsion
    Kiyoshi Suzuki, Makoto Harada, Akihisa Shioi
    1996 Volume 29 Issue 2 Pages 264-276
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.264
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    The growth mechanism of CdS ultrafine particles in water-in-oil microemulsions was investigated. The growth occurs via a irreversible particle coagulation process. Its rate constant is dependent on the agglomeration number of a particle n. At small agglomeration numbers, the rate constant k is about 107 dm3mol–1s–1. It decreases dramatically to about 103 dm3mol–1s–1 at a critical agglomeration number nc followed by a further decrease in k above 2nc. This causes sharpening of the size distribution near nc and 2nc. A simple model based on the coagulation process with n-dependent rate constants is proposed, which explains well the experimental results. The effects of initial mixing and the feed ratio of Cd2+ to S2– are understood well by the proposed model. The relationship between nc and the stable supramolecules composed of CdS particles was discussed.
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  • Esterification Activity of Lipase Entrapped in Reverse Micelles Formed in Liquefied Gas
    Tadahiro Murakata, Kazuhisa Yusa, Manabu Yada, Yosihiro Kato, Shimio S ...
    1996 Volume 29 Issue 2 Pages 277-281
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.277
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    For AOT-water-liquefied gas systems, we studied formation of reverse micelles, entrapping of lipase into water-pools of the reverse micelles, and esterification activity of the entrapped lipase. The formation of reverse micelles was confirmed with visual observation using a dye soluble in water for liquefied ethane and propane, but was not done for liquefied CO2. Water was solubilized as water-pools in large quantity for the system using liquefied propane and in small quantity for that using liquefied ethane. The entrapping of lipase was confirmed for the system of liquefied propane using lipase labelled with a fluorescence probe. The entrapped lipase exhibited high catalytic activity for esterification of lipophilic substrates, though the activity was a little lower than that in AOT reverse micellar solution formed using hexane as an organic medium. The activity varied with mole ratio of water to AOT, [H2O]/[AOT], and was maximized at a certain value of [H2O]/[AOT]. The value of [H2O]/[AOT] almost agreed with that in a AOT-hexane reverse micellar solution.
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  • Theoretical Analysis of Collection Characteristics of a Solar Air Heater with a Built-in Net
    Edmond M. Hido, Makoto Nishimura
    1996 Volume 29 Issue 2 Pages 282-288
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.282
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    The collection characteristics of a solar air heater with a built-in net, in which a metallic net was inserted parallel in the space between the transparent cover plate and the absorber, were theoretically analyzed. The working fluid (air), which entered the solar air heater at a uniform inlet velocity and a constant inlet temperature, was divided into two layers (upper and lower layer) by the metallic net. Solar radiation impinges uniformly from above, passing through the transparent cover plate and being absorbed partly by the net and partly by the absorber. For the present solar air heater, the continuity, momentum and energy equations were derived under several assumptions and numerically solved. The calculations were performed for the cases of eight kinds of metallic nets which had different transmissivities, under different combinations of mass flow rate of air and incident solar radiation. Also, the cases of a conventional solar air heater and a solar air heater without a net were theoretically analyzed. The calculated results were compared with the experimental data reported in a previous paper, and the effects of the net transmissivity, net setting position and solar air heater length on temperature distributions within the air layer and the collection efficiency were examined.
    The calculated results show fairly well the tendencies of the experimental data, and the several assumptions made and the calculation method used in the theoretical analysis are found to be valid.
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  • Characteristics of Separation of Carnitine and Metal Ions in Cheese Whey Model Solution by Loose Reverse Osmosis Membrane
    Jian-Hua Xu, Hiroshi Echizen, Xin-Hui Xing, Shinjiro Yamamoto, Hajime ...
    1996 Volume 29 Issue 2 Pages 289-293
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.289
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    Aiming at recovering carnitine from cheese whey by using loose reverse osmosis membranes, rejection characteristics of several components in the whey were examined by using model solutions. An electroneutral membrane was found to be most effective for the separation. The rejection of carnitine was above 0.95 independent of the pH of solutions, while monovalent metal ions showed low rejections of 0.1–0.3. On the other hand, the rejections of divalent metal ions decreased with increase of the pH, and reached a minimum of about 0.5. As a result, mono- and divalent metal ions could be removed simultaneously by adjusting the pH of the feed solutions. To clarify the effect of pH on the rejection, the permeate of MgCl2 aqueous solution was examined. The rejections of MgCl2 were greatly affected by the pH and showed the same tendency as the mixed solution. The effect of the pH on permeation of electrolyte was considered to be caused mainly by the adsorption of ions on the membrane.
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  • Vapor-Liquid Equilibria at 101.32 kPa Mixtures of Butyl Esters and Propan-2-ol
    Eduardo Gonzalez, Ortega
    1996 Volume 29 Issue 2 Pages 294-299
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.294
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    The concentrations of the vapor-liquid equilibria have been measured in a small capacity recirculating still for the binaries composed of four butyl esters (from methanoate to butanoate) and propan-2-ol at a constant pressure of 101.32 kPa. VLE data were thermodynamically verified with the point-to-point test and the predictions made using several group-contribution models were acceptable but with some exceptions. An azeotrope was found for (x1butyl methanoate + x2propan-2-ol) at x1 = y1 = 0.038 and T = 354.9 K.
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  • Electro-Ultrafiltration of Reverse Micelles Containing Enzyme
    Masaru Hakoda, Kozo Nakamura, Atsushi Enomoto, Teruhiko Hoshino
    1996 Volume 29 Issue 2 Pages 300-306
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.300
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    The electro-ultrafiltration of reverse micelles was investigated for use as a membrane reactor for continuous enzymatic reaction. A ceramic membrane module of tubular type was used to separate the Aerosol OT reverse micelles containing lipase from the continuous phase of iso-octane. The rejection of reverse micelles as well as the permeation flux were measured under different conditions of applied voltage, flow velocity and trans-membrane pressure.
    The permeation flux increased with increase in the applied voltage, and the application of an electric field improved the ultrafiltration efficiency of the reverse micelles containing enzyme. When the anode and the cathode were set in the permeate side, and in the retentate side respectively, the flux was larger than that obtained with the reverse setting of the electrodes.
    The dielectrophoretic force as well as the electrophoretic force were supposed to influence the movement of the reverse micelles in the membrane module where the electric field was nonuniform.
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  • Packed Column Distillation Simulation with a Rate-Based Method
    Hideki Mori, Akiyoshi Oda, Tsutomu Aragaki, Yasuhiro Kunimoto
    1996 Volume 29 Issue 2 Pages 307-314
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.307
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    A simulation algorithm using a rate-based model is proposed for multicomponent packed column distillation. The packed column sections are divided into small segments for the modeling. For each packing segment, (6c + 7) MERQ equations are set up and solved by an equation-tearing method with two calculation loops. Calculation of the whole column consists of an iterative segment-wise algorithm with the correction of the bulk vapor composition by the overall normalized θ method for acceleration.
    The numerical characteristics of the proposed algorithm and some remarks on its application are illustrated using numerical examples and experimental data obtained from a pilot-scale plant.
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  • Mixing Rules for Accurate Prediction of Vapor-liquid Equilibria of Gas/Large Alkane Systems Using SRK Equation of State Combined with UNIFAC
    Chongli Zhong, Hirokatsu Masuoka
    1996 Volume 29 Issue 2 Pages 315-322
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.315
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    Two new mixing rules have been proposed and tested in this work. Both are more accurate than the modified Huron-Vidal mixing rule (MHV1) for gas/large alkane systems. The new mixing rule 1 (MR1), in which a correction factor to GE from UNIFAC is introduced in MHV1 and correlated with carbon number, gives very good predictive accuracy for gas/large alkane systems, where MHV1 performs poorly. The present work shows that although MHV1 itself can not predict the VLE of a highly asymmetric system with good accuracy, a simple modification can greatly improve its accuracy, and make it useful for highly asymmetric systems. In addition, MR1 is compared with a recently proposed model named LCVM, which is a linear combination of Vidal (1978) and Michelsen (1990b) mixing rules (Boukouvalas et al., 1994). MR1 gives better results than LCVM, and the advantage of MR1 over LCVM becomes evident with increasing carbon number, which shows that MR1 is more reliable for extrapolating to larger alkanes than LCVM. On the other hand, a new linear mixing rule for am/bm is introduced into MHV1 to replace the linear mixing rule for bm, which constitutes the new mixing rule 2 (MR2). The results show that MR2 is superior to MHV1, especially for systems with high asymmetry, which leads to the conclusion that a linear mixing rule for am/bm is more suitable for highly asymmetric systems than for bm.
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  • A Flexible Simulation System for Scheduling with Various Constraints
    Shinji Hasebe, Yoshihiro Murakami, Iori Hashimoto
    1996 Volume 29 Issue 2 Pages 323-329
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.323
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    A simulation system, which can be widely used to determine the starting times of operations for general batch plants, is proposed. The operations of a batch plant are first expressed by a sequence of basic operations such as filling, processing, discharging and cleaning. By using these basic operations, the simulation problem can be reduced to that of determining the starting times of the basic operations.
    A variety of constraints are grouped into four types, and it is demonstrated that the constraints on finite intermediate storage can be converted into the constraints on precedence relationships of basic operations. Then, for each of the three types of constraints, simulation modules to calculate the earliest and latest starting times of basic operations are developed. A simulation program to calculate the starting times of basic operations which satisfy all types of constraints can be generated by combining these simulation modules.
    The major feature of the proposed method is that the simulation program can be easily modified by recombining the simulation modules. Therefore, a simulation program with sufficient flexibility can be developed by using the proposed method.
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  • Elutriation of Fine Powders from a Fluidized Bed of a Binary Particle-Mixture
    Xiaoxun Ma, Yoshinori Honda, Nobuyoshi Nakagawa, Kunio Kato
    1996 Volume 29 Issue 2 Pages 330-335
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.330
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    The elutriation of fine powders (Group C or A powders in Geldart’s classification) from a fluidized bed of fines-coarse particle mixtures had been investigated in a transparent column with diameter of 7.1 cm and height of 102 cm. In the experiments, a silica sand (Group B in Geldart’s classification) was used as the coarse particles, whereas several kinds of limestone powder varying in Geldart’s classification from A to C were used as fines. The elutriation rate constant of fine powders was obtained by measuring the elutriation rate of powders, and the concentration of powders in the bed at steady state. The effects of superficial gas velocity, concentration of powders in the bed and diameter of powders on the elutriation rate constant were investigated. Experimental results showed that the elutriation rate constant of powders reaches a maximum at a certain powder size corresponding approximately to the boundary between Group A and C powders, giving an indication of the different elutriation mechanisms between Group A (or B) particles and C powders. This finding is contrary to the assumption made by existing models for the prediction of elutriation rate of Group A and B particles and may be attributed to the powder cohesivity.
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  • Analysis of Separation Performance for High Performance Liquid Chromatography
    T. Hatanaka, M. Ishida
    1996 Volume 29 Issue 2 Pages 336-343
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.336
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    A diagram to systematically represent the separation performance for a wide range of operating conditions of high performance liquid chromatography is proposed. It is called a separation performance diagram, showing the relationship between the dimensionless parameter related mainly to the material, kp′, and the dimensionless parameter on the elution time, uT/εL – 1, for the specified values of yield. The parameter, kp′, is the capacity factor measured from the center of a rectangle input. It is equal to the value of uT/εL – 1 when the yield of the product is 0.5. This parameter becomes k0′ for the linear Isotherm. The line for the specified yield in the diagram becomes straight when the parameters related to non-linearity, bC0 and utp/εL, are specified. The purity of the product is determined from these yields, and the operating conditions such as time interval of sample injection tp and the cut time T can be obtained from the diagram. Since kp′ is equal to uT/εL – 1 for yield = 0.5, the value of the abscissa kp′ is determined from the location at yield = 0.5 of the elution curve obtained from experiments, and the diagram can be drawn. The effectiveness of the diagram is confirmed by applying it to obtain the period between successive injections and the cut time on two-step chromatography. It is also shown that this diagram can be applied to the separation of the mixture with interaction among components.
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  • A Numerical Consideration on Dynamic Modeling and Control of Ideal Heat Integrated Distillation Columns
    Kejin Huang, Masaru Nakaiwa, Takaji Akiya, Kazumasa Aso, Takeichiro Ta ...
    1996 Volume 29 Issue 2 Pages 344-351
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.344
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    In this paper, an ideal heat integrated distillation column (HIDiC), which has neither a reboiler nor condenser, is considered. A dynamic model, capable of doing both static and dynamic simulations of the ideal HIDiC is derived. Based on this model, the system properties and control feasibility are studied. It is found that the ideal HIDiC could be regulated quite well with manipulation of feed thermal condition and the pressure of either rectifying or stripping section. The efficient way to control its top and bottom product qualities is to use composition inferential systems to realize direct composition control.
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  • Sedimentation Behavior of Protein Solutions in Ultracentrifugation Field
    Eiji Iritani, Koji Hattori, Sin-ya Akatsuka, Toshiro Murase
    1996 Volume 29 Issue 2 Pages 352-358
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.352
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    An analytical ultracentrifluge was used to characterize the behaviors of ultracentrifugal sedimentation of bovine serum albumin solutions. We obtained data both for the sedimentation velocity and for the growth rate of the sediment that accumulates during ultracentrifugation. Effects of the rotor speed, the solution concentration, and the volume of the solution contained in the cell on the sedimentation behaviors were investigated experimentally. The sedimentation behaviors and the properties of the compressible sediment were explained well in terms of the theory which has been applied with respect to particulate suspension. Finally, it was shown that such factors of the solution environment as the solution pH and the salt concentration have a large effect on the sedimentation behaviors.
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  • Ab Initio Molecular Orbital Study on Gas-Phase Adsorption on Silica Gel
    Hajime Tamon, Makoto Hirano, Tatsuya Hayakawa, Tetsuo Suzuki, Morio Ok ...
    1996 Volume 29 Issue 2 Pages 359-364
    Published: 1996
    Released on J-STAGE: March 17, 2005
    DOIhttps://doi.org/10.1252/jcej.29.359
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    Adsorption of nine different gases and vapors on a silica gel was studied based on ab initio MO calculations. A single-type adsorption site constructed by one silanol group, and a paired-type adsorption site by two silanol groups were used as molecular models for adsorption sites on the silica gel. Adsorption structure and interaction energy were determined for the molecular models, and a decomposition of the energy was carried out.
    Adsorption equilibria of the nine gases and vapors on the silica gel were measured, and differential heats of adsorption were determined by applying the Clausius-Clapeyron equation to the measured isotherms. The interaction energy estimated by the MO calculation roughly corresponded to the measured heat of adsorption. The single-type adsorption site is favorable for adsorption of ammonia. The interaction energies of ethylene were almost the same on both adsorption sites. In the adsorption of alcohols, water, benzene and sulfur dioxide, the paired-type adsorption site gave a more stable adsorption structure than the single-type site.
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