Special Issue [Formation of Ordered Structure in Liquid Phase and Its Use for Materials Design]
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Makoto Harada
2001 Volume 27 Issue 6 Pages
663-677
Published: November 20, 2001
Released on J-STAGE: December 30, 2008
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One of the most important problems in the field of chemical engineering is the design of hierarchical materials that are ordered on all length scales from the molecular level to the nano-, meso- and macro-scales. The processes of the structure formation using liquid states play an important role in the design of hierarchical mateials. In this work, silica-mesoporous materials were selected as an example of the hierarchical materials. The processes of structure formation were discussed based on extensive results obtained by many researchers, and the problems to be performed in the field of chemical engineering were extracted: 1) structure formation processes in non-equilibrium states, 2) role of macroscopic interface between phases in the structure formation, 3) evaporation-induced structure formation and 4) external field alignment of ordered structures. The future approaches to the design of hierarchical materials are also reviewed.
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Hiroshi Sato, Keiko Suzuki, Isao Komasawa
2001 Volume 27 Issue 6 Pages
678-682
Published: November 20, 2001
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The kinetic behavior for coagulation of ultrafine CdS particles in reverse micellar and homogeneous aqueous solutions was studied with the aim of understanding the effect of compartmentalization of the particles in reverse micelles on the kinetic behavior. Rapid coagulation of CdS particles in aqueous solution is controlled by the addition of water-soluble thiol-terminated ligands, which are adsorbed on the surface of the particles. The presence of the thiols was found to reduce the rate for coagulation of CdS particles in the reverse micelles as well as in the aqueous solutions. The rate for coagulation was analyzed on the basis of the pseudo-continuous phase model, in which the water cores in the reverse micelles were assumed to act as a continuous phase via the rapid exchange of the contents of the cores. The rate constants for both systems were found to be almost identical, except in the case of the reverse micellar systems of a low water content, where the reverse micelles are as small as the particles.
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Kazunori Kamio, Masahiro Kinoshita
2001 Volume 27 Issue 6 Pages
683-689
Published: November 20, 2001
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Phase separation in a mixture of small and large colloidal particles and the interaction induced between a macromolecule (a large particle) and a cell membrane (a surface) immersed in smaller molecules (small particles), have been analyzed using an integral equation theory. Simplified models are employed to study the entropically driven formation of ordered structure, which is ascribed to the excluded volume effects (forces of increasing the system entropy by reduction of the total excludedvolume for the small particles). In the analysis on the induced interaction, attention is focused on effects due to the packing fraction of the small particles, the diameter of the large particle, the surface curvature, presence of a small amount of particles slightly larger than the small particles, and attractive interaction between the small particles. A significant finding is that considerable specificity exists between the diameter of the large particle and the surface curvature. Works on the roles of the excluded volume effects in the "lock and key" steric interactions between macromolecules and protein folding inbiological systems, which are in progress in our group, are also discussed.
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Akihisa Shioi, Tomoyuki Abe, Hiroto Kumagai, Gaku Usuba, Satoshi Kondo
2001 Volume 27 Issue 6 Pages
690-695
Published: November 20, 2001
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We calculated the composition at liquid/liquid interface when surfactant A moved from one bulk phase to another. The surfactant was able to react with chemical species M in the latter bulk phase to produce surfactant B. The homogeneous distribution of A and B at the interface was in spinodal regime, and spinodal decomposition could occur. A-rich domain formed by the spinodal decomposition could react with M, while B molecules were desorbed to a bulk phase cooperatively. We described the kineti cprocess by time-dependent Ginzburg-Landau equation taking into account the interfacial reaction and cooperative desorption. Calculated time-dependency of interfacial composition exhibited the oscillation which was compared with the oscillation of interfacial tension observed experimentally. Some statistical properties of the both oscillation patterns were similar to each other.
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Kazuo Kondo, Kumiko Shimada, Zennosuke Tanaka
2001 Volume 27 Issue 6 Pages
696-699
Published: November 20, 2001
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The incorporation mechanism of Ti02 particles into zinc electrodeposit is reported. Two types of TiO
2 particles exist, namely, 50 nm in diameter coarse particles and 10 nm in diameter fine particles. The coarse particles precipitate on the (00·1)
η as lined up particles along the laterally growing macro stepsand as randomly dispersed particles. The sidewalls of macro steps incorporate coarse particles at the edge of the (00·1)
η. The atomic steps may incorporate the bottom of the randomly dispersed coarse particles. The fine particles precipitate on the (00·1)
η as randomly dispersed particles and they might be incorporated into the atom. Also, with orientation image mapping, size of (00·1)
η orientation and size of hexagonal platelet crystals coinside.
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Kenji Mishima, Kiyoshi Matsuyama, Atsushi Furukawa, Takashi Fujii, Jun ...
2001 Volume 27 Issue 6 Pages
700-706
Published: November 20, 2001
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A novel method to control coating thickness of microcapsules is reported for polymer microcapsules containing inorganic microparticles, in this case silica balloon, iron, silica balloon coated by TiO
2 using gas-liquid cosolvency of supercritical carbon dioxide. A suspension of inorganic microparticles incarbon dioxide (CO
2) containing a cosolvent and dissolved polymer is sprayed through a nozzle toatmospheric pressure. The polymers are poly(styrene)-poly(methyl methacrylate)-poly(glycidylmethacrylate) triblock copolymer (PS-b-(PMMA-co-PGMA); M.W.=5,000), poly(methyl metha-crylate) (PMMA; M.W.=15,000), poly(ethylene glycol) (PEG; M.W.=7,500), poly(L-lactic acid) (PLLA; M.W.=5,000), and PEG-poly(propylene glycol) (PPG)-PEG triblock copolymer (M.W.=13,000). The solubilities of these polymers in CO
2 increase significantly with the use of low molecular weight alcohols as cosolvents. After expansion, the particles do not tend to agglomerate, since the purecosolvent is a nonsolvent for the polymer. The structure and morphology of the microcapsules were investigated by SEM with EPMA, TEM, laser-diffraction particle-size analysis, and optical microscopy. The thickness of the polymer coating about the silica balloon, and likewise, the mean particle diameterand particle size distribution could be controlled by changing the feed composition of the polymer.
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Kiyoshi Matsuyama, Satoru Yamauchi, Takuji Hirabaru, Ken-Ichiro Hayash ...
2001 Volume 27 Issue 6 Pages
707-713
Published: November 20, 2001
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A new polymer-blend microencapsulation, rapid expansion from supercritical solution with anonsolvent (RESS-N), is reported for forming polymeric microparticles containing proteins, in this caselipase (from Pseudomonas cepacia) and lysozyme (from chicken egg white). A suspension of protein incarbon dioxide (CO
2) containing a cosolvent and dissolved polymer is sprayed through a nozzle toatmospheric pressure. The polymers are poly (ethylene glycol) (PEG 4000; M.W. = 3,000, PEG 6000; M.W. = 7,500, PEG 20000; M.W. = 20,000), poly (methyl methacrylate) (PMMA; M. W. =15 , 000), poly(L-lactic acid) (PLLA; M.W.=5,000), poly (DL-lactide-co-glycolide) (PGLA; M. W.=5,000) andPEG-poly (propylene glycol) (PPG) -PEG triblock copolymer (PEG-PPG-PEG; M. W. =13 , 000). Thesolubilities of these polymers in CO
2 increase significantly with the use of low molecular weight alcoholsas cosolvents. After expansion, the particles do not tend to agglomerate, since the pure cosolvent is anonsolvent for the polymer. The structure and morphology of the microcapsules were investigated byTEM, SEM with EPMA, laser-diffraction particle-size analysis, and optical microscopy. The thicknessof the polymer coating about the protein, and likewise, the mean particle diameter and particle sizedistribution could be controlled by changing the feed composition of the polymer.
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Miki Funai, Masahiro Goto, Shintaro Furusaki
2001 Volume 27 Issue 6 Pages
714-718
Published: November 20, 2001
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Extraction of oligonucleotides by a cationic surfactant was investigated in a liquid-liquid extraction system. A cationic surfactant having two long-alkyl chains proved to be effective for the extraction of oligonucleotides from an aqueous to an organic phase. Important parameters affecting the efficiency of the extraction were the kind of surfactants, alcohol content, salt concentration, pH of the feed solutionand the operational temperature. The sequence of oligonucleotides also affected the extraction behavior. Back extraction was successfully performed by adding proper alcohol and salt in the recovery phase.
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Masahiro Katoh, Jyunji Kataoka, Yoshinori Maegawa, Tahei Tomida
2001 Volume 27 Issue 6 Pages
719-723
Published: November 20, 2001
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To modify the adsorption characteristics of the mesoporous silica FSM-16, Al-incorporated FSM-16 (Al-FSM-16) and trimethylsilylated FSM-16 (TMS-FSM-16) were prepared. The pore structureand the adsorption characteristics of these modified mesoporous materials were examined by usingprobe molecules of N2 and CO
2. BET surface area of Al-FSM-16 was reduced to 470 m
2·g
-1, about one-half of the surface area of FSM-16. However, the separation factor for CO2 from CO
2-N
2 gas mixtures (CO
2/N
2=20.1/79.9) on Al-FSM-16 was higher than on FSM-16 in the total pressure range from 0.2 to 0.3 MPa. This implies that CO
2 is adsorbed selectively to Na+, which is present to compensate for thenegative charge generated by incorporating Al in the framework of the mesoporous silicas. By trimethyl-silylation of FSM-16, 82% of the surface area was covered with trimethylsilyl (TMS) groups, and thepore size decreased to 2.3 nm from the 2.8 nm of FSM-16. Much less CO2 was adsorbed on TMS-FSM-16 than that on FSM-16, possibly due to the smaller amount of free SiOH groups of TMS-FSM-16.
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Minori Kawai, Yoshikazu Miyake
2001 Volume 27 Issue 6 Pages
724-729
Published: November 20, 2001
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Titanium tetra-isopropoxide (TTIP) was dissolved in hydrochloric acid solution to prepare atransparent titania sol solution. Titania precipitates were obtained by aging a mixed solution of thetitania sol and a hydrophilic polymer for 24 hours at 60°C.
In the presence of polyacrylacid (PAA), gelation or precipitation is occurred depending on theconcentration of PAA and TTIP. White powders of titania were obtained by calcination of the gel orprecipitation. These powders were anatase type with specific area larger than 100 m
2/g. The titaniaobtained via gelation is anatase mesoporous titania, which possesses a sharp peak of pore size distribu-tion. A peak is observed in the low angle of XRD pattern for both as-synthesized and calcinedmesoporous titania. The result suggests that titania has a regular nano-structure, which is retained aftercalcination.
In the polyethyleneglycol (PEG) system, no gelation of the solution took place under these experi-mental conditions. The titania powder became rutil-type with increasing in the concentration of PEG.Both specific area and pore volume of the titania powder decreased. Furthermore, the pore sizedistribution of the titania is broader than that of the PAA system.
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Yoshiki Fujita, Yoshikazu Miyake
2001 Volume 27 Issue 6 Pages
730-735
Published: November 20, 2001
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Water-in-oil microemulsions (W/O type ME) were prepared by dissolving the anionic surfactantAOT in heptane. The effects of temperature on the electric conductivity of the emulsions were measuredat constant
W>O value, which is defined by concentration ratio [H
2O]/[AOT]. The electric conductivityincreased abruptly at a certoin temperature (
TP) to reach a maximum value, then decreased slightly.The value of
TP decreased with the increase in the
WO value. The maximum conductivity was indepen-dent of the
WO value, but increased with AOT concentration, i. e., the concentration of ME. The observedmaximum conductivity was about a half of the calculated value, which was estimated by the ionicequivalent conductance of Na ion dissolved into water pool of ME. This result is independent of the Wovalue and AOT concentration. The sharp increase of conductivity can be interpreted as the result of achange in the micro-structure of the emulsion, i. e., the formation of a percolated structure.
Gelaton was added to the ME to fix the percolated structure, and a transparent microemulsion-based organogel (MBG) was obtained. The electric conductivity of MBG was smaller than themaximum conductivity of ME, but its value increased with
WO value. The conductivity of MBG wasalmost independent of temperature, and the percolated structure of ME was thought to have been fixedin the microstructure of MBG.
A lipase was fixed in the MBG and the hydrolysis of 2-naphthylacetate was analused. The reactionrate and the efficiency of the MBG system were smaller than those of ME.
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Yasushige Mori, Shin-Ichi Okamoto, Takuji Asahi
2001 Volume 27 Issue 6 Pages
736-741
Published: November 20, 2001
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Gold nanoparticles were prepared by the reduction of sodium tetrachloroaurate in water-in-oilmicroemulsion, by using polyoxyethylene dodecyl ether, bis 2 ethylhexyl sodium sulfosuccinate, ordidodecyl dimethyl ammonium bromide as a surfactant. When the molar ratio of water to surfactantbecame small, the size of microemulsion was almost monodispersed, and nanoparticles were producedand dispersed well in microemulsion solution. Furthermore, monodispersed nanoparticles were obtainedwhen the number of gold ions per water droplet in microemulsions was above one. The diameter of goldnanoparticles was controllable by the average size of microemulsion. By use of a strong reducing agentsuch as hydrazine or sodium borohydride, small gold particles could be made.
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Taisuke Maki, Hideto Matsuyama, Masaaki Teramoto
2001 Volume 27 Issue 6 Pages
742-748
Published: November 20, 2001
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The effects of quench temperature, initial polymer concentration and cooling rate on the evolution of pore structure for the system PMMA/cyclohexanol by thermally induced phase separation (TIPS) method was examined by the simulation of the spinodal decomposition based on the model of Cahn-Hilli ard formalism. The domain size of spinodal decomposition structure increased with the increase in the quench temperature or the decrease in polymer. With the increase in the cooling rate, the temperature at which the droplet structure was formed decreased. Therefore, the size of the spinodal decomposition structure decreased.
The structure formation was also simulated, under conditions of a distribution of quench temperature, initial polymer concentration or the cooling rate. The growth of asymmetric structure was observed, because domain size of spinodal decomposition structure was dependent on temperature and polymer concentration in the identical structure.
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Youhei Saito, Mikio Konno
2001 Volume 27 Issue 6 Pages
749-752
Published: November 20, 2001
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To study the mechanism of nanoparticle formation in hydrolysis and condensation of tetraethyl orthosilicate (TEOS), the reaction was performed over a wide range of TEOS concentration (0.01~0.2 mol/dm
3), water concentration (5~20 mol/dm
3) and ammonia concentration (0.2~1.5 mol/dm
3) in the absence and in the presence of LiCl and KCl as electrolytes. Nanoparticles with an average diameter of 23~100 nm were formed at the lowest ammonia concentration of 0.2 mol/dm
3 in the absence of the electrolytes. The effect of electrolyte concentration on particle diameter and the measurement of electric conductivity of the reaction system suggest that electrostatic repulsion between particles precipitated in the reaction system is the main factor determining final particle size. The formation of nanoparticles in the reaction is explained by an increase in the electrostatic repulsion due to a decrease in ionic strength.
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Kazuya Uezu, Noboru Tazume, Masahiro Yoshida, Masahiro Goto, Shintaro ...
2001 Volume 27 Issue 6 Pages
753-755
Published: November 20, 2001
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In creating highly selective imprinted polymers is important to make the polymer matrix rigid andattach the functional host molecule firmly onto the polymer surface. In the present study, the molecularweight distribution of surface molecular imprinted polymers prepared without a crosslinking agent wasmeasured, and the essential factors affecting the characteristics of the polymer matrix were examined.The optimum polymerization conditions based on the results were applied, and we succeeded in enhanc-ing the imprint effect and the selectivity of Zn(II)-imprinted polymers.
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Hiromi Shirai, Makoto Kobayashi, Makoto Nunokawa
Article type: Technical Research Paper
Subject area: Catalysis, Kinetics and Reactor Design
2001 Volume 27 Issue 6 Pages
771-778
Published: November 20, 2001
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Honeycomb type iron oxide sorbent, which removes H
2O and COS in hot coal gas, has beendeveloped. The fixed bed reaction model for the desulfurization using the sorbent and H
2O removalCharacteristics were studied using simulated coal gas.
In the fixed bed reactor, the reaction zone in which the sorbent react to sulfur compounds (H
2O,COS) is formed. After that, this reaction zone moves to gas outlet. When the front of the reaction zonereaches gas outlet, the breakthrough of sulfur compounds starts. This fixed bed reaction phenomena wasshown in a numerical formula model. On the other hand, the H
2O reaction rate of the sorbent could beestimated by approximate numerical formula model using unreacted core model and effective diffusivityof H
2O in the sorbent, which is need to estimate the reaction rate, was obtained in sulfidation usingthermo gravimetric analyzer. The fixed bed H
2O removal characteristics by these reaction models wereestimated and compared with actual H
2O removal data. These Results showed that proposed reactionmodel made it possible to easily estimate desulfirization characteristics in a fixed reactor.
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Masahiro Shishido, Keisuke Okubo, Motofumi Saisu
Article type: Fundamental Research Paper
Subject area: Catalysis, Kinetics and Reactor Design
2001 Volume 27 Issue 6 Pages
806-811
Published: November 20, 2001
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In supercritical water oxidation of glucose, the effect of oxygen concentration on the productionrate of gaseous components (CO, C0
2, H
2 and CH
4) was examined at 400-470°C and 18.5, 25..5 MPa withresidence times of less than 30 sec in a flow-type reactor. Hydrogen peroxide was used as an oxidant.Oxygen was produced by hydrogen peroxide decomposition. Oxygen concentration was varied from 50to 250% compared with nominal stoichiometric oxygen concentration. The experimental resultsrevealed that the oxygen concentration did not signtficantly influence the yields of gaseous components,and that the amounts of gaseous products increased with residence time up to 5 sec and then reached aplateau. Apparent rate analysis was carried out based on the assumption that the overall production rateof carbon-containing gaseous speacies is proportional to glucose concentration. The result suggests thatthe initial stage of oxidation up to 5 sec of residence time was described by first-order kinetics. AnArrhenius plot of the obtained apparent first-order rate constant showed that the ratio of frequencyfactors for oxygen concentrations of 100 and 200% was almost equivalent to the oxygen concentration ratio.
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Takao Ohmori, Masaru Nakaiwa, Akira Endo, Takaji Akiya, Takashi Amemiy ...
Article type: Fundamental Research Paper
Subject area: Catalysis, Kinetics and Reactor Design
2001 Volume 27 Issue 6 Pages
812-818
Published: November 20, 2001
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Behavior of a chemical reaction system for converting methanol to light olefins in a fixed-bed reactor under a periodic operation was investigated via numerical simulation to improve the efficiency of the system through the enhancement of yields of the desired products such as ethylene and propylene. In the periodic operation, the reactor wall temperature was set to vary sinusoidally along its axis. The recycling of by-products such as pentene and butylene was also studied. As a result, we found that the combination of the wall temperature modulation and the recycling of pentene led to the possible increases in the ethylene and propylene yields of up to ca. 33% and ca. 16%, respectively, compared with those obtained with a uniform wall temperature. Further, it was shown that the product ratio of propylene to ethylene can be changed in the range of 1.60 to 6.05 when butylene is recycled. This suggests that production with variable composition of ethylene and propylene according to need is possible by changing the wall temperature modulation and the recycling ratio even in the same reactor.
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Akitoshi Seya, Ichiro Tadano
Article type: Technical Research Paper
Subject area: Safty, Enviroment and Energy
2001 Volume 27 Issue 6 Pages
765-770
Published: November 20, 2001
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Phosphoric acid fuel cells have excess electrolyte in each cell to compensate for acid loss during operation. We studied exprimentally the distribution of excess electrolyte between the anode ribbed plate and the anode substrate. It is found that the amount of excess electrolyte is balanced by the capillary force between the ribbed plate and the substrate. Next, we estimated the cell voltage with various amounts of excess electrolyte. The cell voltage is not influenced by the excess electrolyte when the acid fill level of the anode substrate is within 30%. But when the acid fill level of the anode substrate is over 40%, the cell voltage is influenced by the excess electrolyte in the anode substrate. In this case the diffusion coefficient of anode substrate was estimated 1/10 of that of when the acid fill level is 0%. We concluded that the amount of excess electrolyte must be set such that the acid fill level of anode substrate is within 30%. To increase the amount of excess electrolyte in the cell, we must chose an anode ribbed plate for which the capillary force is larger than that of the anode substrate.
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Yuki Ohno, Daiqing Zhao, Hiroshi Yamashita, Tomohiko Furuhata, Norio A ...
Article type: Fundamental Research Paper
Subject area: Safty, Enviroment and Energy
2001 Volume 27 Issue 6 Pages
779-785
Published: November 20, 2001
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Recently, NO formation and its reduction technology with steam addition in fuel-rich combustionhave been studied in detail. However, only a few studies have been made of the NO formationmechanism in a combustion field of hightemperature and highequivalence ratio with steam addition suchas steam injection-type gas turbine. In this study, numerical analysis of a fuel-rich methane/air counter-flow premixed flame was carried out using detailed chemical kinetics. First, combustion characteristicswithout steam injection equivalence ratios 1.3 and 2.0 were simulated, and the effect of equivalence ratioon NO formation mechanism was discussed. Then, the reduction mechanism of NO formation in fuel-rich combustion caused by steam addition was analyzed. The results showed that the steam additiondecreased the flame temperature and reduced NO formation, and that these effects decreased with theincrease of equivalence ratio. These effects of steam addition on NO formation were found to be causedby two factors: the physical effect of decreasing the flame temperature, and the chemical kinetic effectof decreasing the concentration of CH radicals due to the reaction with added steam.
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Hideki Yamamoto, Noriyuki Heyamoto, Yuko Takami, Junji Shibata
Article type: Fundamental Research Paper
Subject area: Safty, Enviroment and Energy
2001 Volume 27 Issue 6 Pages
786-791
Published: November 20, 2001
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Polyvinylalcohol (PVA) hydrogel was found to be a temperature-sensitive polymeric gel, whose volume and the surface properties changed in the temperature range from 275 K to 310 K.
In this study, a method was proposed for removal of 1,2-dichloroethane from water by adsorption onto a temperature-sensitive PVA polymeric hydrogel. The amount of adsorbed organic compound increased remarkably at temperatures higher than about 310 K, and it was confirmed that the polymeric hydrogel could adsorb and desorb the organic compound according to the temperature change between 323 K and 298 K. It was also observed that the PVA polymeric hydrogel was effective for the removal of an extremely small amount of toxic organic compound in waste water and was repeatedly usable as an adsorbent. The mechanism of the adsorption of 1,2-dichloroethane on PVA polymeric hydrogel could be well explained using the adsorption rate equation based on diffusion in the polymeric hydrogel as the rate determining step.
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Kotaro Tanaka, Takahiro Fujii, Takeo Honda
Article type: Fundamental Research Paper
Subject area: Safty, Enviroment and Energy
2001 Volume 27 Issue 6 Pages
819-823
Published: November 20, 2001
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The present paper discusses the operation of a low-temperature-type AMTEC cell. The cell consistsof a sodium beta″-alumina solid electrolyte tube of 3 mm in outer diameter and capillary tubes of 50 μm in inside diameter. Experiments were conducted with porous molybdenum electrodes, and themeasured maximum power density of the cell was 0.13 Wcm
-2 at 900 K. Electrochemical analysis withthe A.C. impedance measurement was also performed under D.C. polarized conditions, and the internalresistances of the cell were examined. Based on these experimental results, the influence of the sodiumvapor flow resistances in the cathode side for multi-tube type cells was evaluated. The parametricanalysis shows that the low-temperature cell operating at 900 K has a predicted output power of 0.71 Wper unit container base area. In this case, its performance is superior or equal to that of the high-temperature-type cells typically operating at 1,100 K.
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