KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 26 , Issue 4
Showing 1-24 articles out of 24 articles from the selected issue
  • YASUHIRO SHIRAISHI, TAKAYUKI HIRAI, ISAO KOMASAWA
    2000 Volume 26 Issue 4 Pages 487-496
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Novel desulfurization processes for fuel oils, based on photochemical reaction and liquid-liquid extraction, have been investigated. Dibenzothiophene, which is the most difficult compound to desulfurize in the hydrodesulfurization (HDS) process, is used as a model compound. Two extraction systems, oil/water and oil/polar solvent, are employed for desulfurization. In the former system, DBT is photodecomposed the in light oil phase, and is removed into the water phase as a sulfate anion. Although desulfurization is suppressed by the presence of aromatic hydrocarbons, this is improved by the addition of a triplet photosensitizer and hydrogen peroxide. In the latter system, acetonitrile is used as an extraction solvent. When the light Oil is photoirradiated with acetonitrile, DBT dissolved into the acetonitrile is photooxidized into highly polarized compounds, which do not distribute into the non-polar light oil. Thus, in this way, successive removal of sulfur compounds from light oil to acetonitrile is carried out, and the sulfur content of light oil is reduced to less than 0.005wt%. When the electrontransfer photosensitizer is added to the acetonitrile phase, visible-wavelength light (λ>400nm), can be used as a light source. This process is applicable for desulfurization of catalytic-cracked gasoline. An overall desulfurization process, where the solvent and photosensitizer used can be recovered and reused for further desulfurization, is fully organized, and the applicability of the process to the refining Process of fuel oils is examined.
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  • SYOUHEI NISHIHAMA, TAKAYUKI HIRAI, ISAO KOMASAWA
    2000 Volume 26 Issue 4 Pages 497-505
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Analyses of extraction equilibrium formulations for metal ions up to high loading ratios of the extractant were carried out. The extraction equilibrium formulations can be determined by combining the results of the slope analysis method and the stoichiometric compositions of the extract species at the high loading ratios, and these can express the extraction and scrubbing behaviors of metals at all ranges of the loading ratios. The formulations and mass balance equations can be used to construct the separation process with counter-current mixer-settler cascade, leading to the most suitable conditions for separation and purification of metal ions.
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  • KOJIRO SHIMOJO, FUKIKO KUBOTA, TATSUYA OSHIMA, MASAHIRO GOTO, SHINTARO ...
    2000 Volume 26 Issue 4 Pages 506-510
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    A solvent extraction technique was applied to the recovery of rare earth metals from waste television tubes. The acid leach solution of the fluorescent substance which is found in the TV tubes contains europium and yttrium as rare earth metals and a large amount of zinc ions. In the present study, calixarene carboxyl derivative was found to be very useful as an extractant for the separation of rare earth metals and zinc. The addition of sodium ions to the feed material solution strongly enhances the extraction ability in the calixarene extraction system. Further, the synergistic effect facilitates the separation efficiency between rare earth metals and zinc.
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  • EITA ZUSHI, AKIHIRO SAKOGUCHI, FUMIYUKI NAKASHIO
    2000 Volume 26 Issue 4 Pages 511-516
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Using three kinds of novel β-diketone of different alkyl-chain length (1-phenyl-1, 3-octanedione, 1-phenyl-1, 3-tetradecanedione and 1-phenyl-1, 3-icosanedione) and four kinds of neutral phosphorus compounds of different alkyl-chain length (tri-n-butylphosphine oxide, tri-n-octylphosphine oxide), tri -n-butyl phosp ate and tris (2-ethylhexyl) phosphate, the extraction equilibrium of lithium was investigated, and the synergistic effect of these extraction systems was examined, in order to determine the optimum extraction system for lithium.
    It is found that lithium is synergistically extracted by the mixture of β-diketone and neutral phosphorus compounds, and that the ability of lithium extraction with the synergistic reagent of trialkylphosphine oxide is higher than that with tri-alkylphosphate. However, the effect of alkyl-chain length of β-diketone on the extraction equilibrium constants is negligibly small. These results are confirmed by molecular modeling of the extractants and synergistic reagents.
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  • KAZUHARU YOSHIZUKA, KATSUTOSHI INOUE, PETER COMABA
    2000 Volume 26 Issue 4 Pages 517-522
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    A novel molecular mechanics force field for lanthanoid complexes coordinated to O atoms of phosphate, phosphonate, carboxylate, and aqua type ligands is presented. The ligand-metal-ligand (L-M-L) bending interaction is modeled with 1, 3-nonbonded interactions (point on a sphere approach) and a harmonic M-L stretching potential is used for the stretching modes. A quantitative structure property relationship (QSPR) could be obtained, which relates the complexation strain energy difference between the lanthanoid cations and La (III) with their relative extractability. We consider that the molecular mechanics is an efficient tool for the design of next-generation extractants of phosphate, phosphonate and carboxylate types having the specific lanthanoid (III) extractability properties.
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  • RI-E YOKOSAWA, SUSUMU NII, KATSUROKU TAKAHASHI, YOSHIHISA MISAWA
    2000 Volume 26 Issue 4 Pages 523-528
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    A laboratory-constructed flowing liquid membrane apparatus with porous partition (FLM) was applied to the separation of such polyunsaturated fatty acid esters (PUFA-Ets) as eicosapentaenoic acid ethyl ester (EPA-Et) and docosahexaenoic acid ethyl ester (DHA-Et) at 293 K. The hydrophilic porous membrane was used as a partition, and 2M AgNO3 aqueous solution was used as a membrane liquid. By using dodecane as a feed diluent and m-xylene as a recovery solution, PUFA-Ets were successfully separated from mixture of fatty acid esters. The recovery fraction of PUFA-Ets and the separation degree between DHA-Et and EPA-Et were investigated; it increases with the velocity of membrane liquid and the flow path length in the module, while it decreased with the velocity of feed and recovery solution. The recovery fraction of DHA-Et reachs 60% with only 8s-retention time by the continuous operation. The concentrations of the DHA-Et at the outlet of the module were simulated based on the mass transfer model, which gave nearly 85% recovery fraction with 30s-retention time. These results show that a stable operation, a high recovery and a high throughput are realized by the FLM.
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  • YOSHINARI BABA, MINAKO IWAKUMA
    2000 Volume 26 Issue 4 Pages 529-534
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    2-Hydroxy-1-naphthaldoxime (=HNO) containing an oxime group as a ligand was synthesized in order to develop a highly selective extractant for Cu (II) and Pd (II). The extraction selectivity of HNO in chloroform for various metal ions was examined from aqueous ammonium nitrate solution and hydrochloric acid in a batchwise method at 300 K. From aqueous ammonium nitrate solution, Pd (II) was selectively extracted over Cu (II) in the low pH region, while Cu (II) was selectively extracted over Pd (II) in the high pH region because Pd (II) -ammine complexes is attributable not to be extracted with HNO. From hydrochloric acid solution, HNO was found to be a high selective extractant for Cu (II) and Pd (II) over base metals.
    Cu (II) was found to be extracted by the following extraction reaction from aqueous ammonium nitrate solution. HNO behaved as a chelating extractant.
    Cu2++2HR R2Cu+2H+; KCu, KCu=1.6×10102 [-]
    Pd (II) was found to be extracted by the following extraction reaction from hydrochloric acid solution. HNO behaved as a solvating extractant.
    2HR+PdClCu (HR) CuPdClCu; KPd, KPd=1.8×107 (moldm-3) -2
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  • KAZUO KONDO, MICHIAKI MATSUMOTO, TOYO OKUBO
    2000 Volume 26 Issue 4 Pages 535-541
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    The synergistic extraction of gallium (III) with a mixed extractant of acidic organophosphorus compounds such as D2EHPA, DIDPA, and EHPNA as a main extractant and 5-chloro-8-hydroxyquinoline as a synergist diluted by toluene or n-heptane was examined at 298-323 K.
    By adding 5-chloro-8-hydroxyquinoline to the EHPNA extraction system, a remarkable synergistic effect is observed, and the extractability of gallium from the aqueous to organic phases is increased by about 2300 times. However, in the synergistic extraction system of gallium with the mixed extractant, a precipitate was formed in the aqueous phase or at the aqueous-organic interface because of the low solubility of the metal-complex into the organic phase. To overcome this problem, 1-decanol was added to the extraction system as the modifier. The effect of addition of 1-decanol was quantitatively examined. As a result, variation in the extractability of gallium with addition of 1-decanol can be reasonably interpreted in terms of the decrease in the thermodynamic activity of EHPNA and the decrease in the distribution ability of 5-chloro-8-hydroxyquinoline.
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  • KAZUO KONDO, MICHIAKI MATSUMOTO, TAKASHI YOSHIDA, TAKAAKI SONODA
    2000 Volume 26 Issue 4 Pages 542-547
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    New types of lipophilic phthalocyanine derivatives, that is, hexadeca (2, 2, 2-trifluoroethoxy) phthalocyanine and hexadeca (2, 2, 3, 3, 3-pentafluoro-propoxy) phthalocyanine (abbreviated as H2Pc (TFE) 16 and H2Pc (PFP) 16, respectively), were prepared for selective extraction of lithium.
    The extraction equilibria of alkali metals with H2Pc (TFE) 16 and H2Pc (PFP) 16 (H2R) were measured at 303 K. Both the extractants showed the selectivity for lithium extraction in a high pH region. The dependency on pH of the extractability of the alkali metals differed for each metal. The extracted complex of sodium is estimated to be H2RNa+Cl-, and those of lithium are estimated to be Li2R andLiHR for H2Pc (TFE) 16 and Li2R for H2Pc (PFP) 16, respectively. The extracted species of potassium is estimated to be K2Pc (TFE) 16. Each extraction equilibrium constant for alkali metals with the extractants was calculated.
    The extraction rate of lithium with K2Pc (TFE) 16 was measured by using a stirred transfer cell. The extraction process is considered to be limited by the diffusion of the extractant.
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  • KATSUTOSHI INOUE, KAZUHARU YOSHIZUKA, KEISUKE OHTO, SUMITO SEKI
    2000 Volume 26 Issue 4 Pages 548-550
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    O, O′-Decanoylchitosan was synthesized from chitosan, a basic polysaccharide produced from shells of Crustacea such as crabs, shrimps and so on, by acylating its hydroxyl groups. Although it was insoluble in aliphatic diluents such as kerosene, it was soluble in toluene and chloroform. Solvent extraction of some metal ions with O, O′-decanoylchitosan in chloroform was tested and compared with the adsorption on chitosan. It was found that iron (III) was not practically extracted with this solvent though it was selectively adsorbed on chitosan over copper (II). Selective extractive separation of trace concentration of copper (II) was achieved from large excess of iron (III) at pH about 2.
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  • GUILIN PIAO, KAZUHIDE HAKAMADA, MOTOHIRO KONDOH, MASATAKA YAMAGUCHI, S ...
    2000 Volume 26 Issue 4 Pages 551-556
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    The combustion process in a fluidized bed has been recognized as a promising combustion processes for Refuse Derived Fuel (RDF). To explain the behavior of chlorine compound during the combustion of RDF in the fluidized bed process, two kinds of RDF were burnt in a 0.3×0.3m bubbling-type fluidized bed combustor. One was model RDF produced from raw materials with controlled combination ratios, simulating the RDF produced from municipal solid waste (MSW), and the other was commercial RDF produced from MSW. Combustion test were carried out for a extenden period under steady state conditions. The hydrogen chloride (HCl) concentration in the flue gas was measured on various points in the process and the total weight of solid in the bed, from the cyclone, from the gas cooler and from the bag filter was measured after each test run. Material balances of silica sand, ash, and chlorine were calculated. It was found that the material balance between feed rate and outflow rate of chlorine compound agreesd within 10%. For the model RDF, 80% of fed chlorine was removed by solid components during RDF combustion in the bed and only 4.1% chlorine was discharged with the flue gas in the combustor exit. The chlorine captured by calcium remaining in the bed was 46.7% and the rest was captured by the particles entrained from the bed. For the RDF from MSW, 50% chlorine was removed by solid components in the bed and 21.9% chlorine was discharged with flue gas from the bed. 27.7% of the chlorine captured by calcium compound remained in the bed and the rest was entrained from the bed. Although potassium and sodium contained in the sand and in the RDF are assumed to completely react with chlorine, more than 80% of chlorine for the case of model RDF and more than 50% of chlorine for RDF from MSW are captured as CaCl2.
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  • SEI MURAKAMI, RYUSEI NAKANO, TATSUHIKO MATSUOKA
    2000 Volume 26 Issue 4 Pages 557-562
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    In order to obtain common specifications for an industry fermenter for scale up reference and new development basis, we have surveyed 480 fermenters which had actually been manufactured. Industrial fermenters of up to hundreds of cubic meters capacity have the following standard specifications; tank height/diameter 1.8; working volume/total volume 0.7; heat transfer area/working volume 5m-1 (1-2m-1 for large scale fermenters); agitation power 6kw/m3 (2kw/m3 for large scale fermenters); impeller spacing/impeller diameter 1.4; impeller diameter/tank diameter 0.38; impeller tip speed 5.5 m/s. Among the surveyed parameters, tank height/diameter and impeller tip speed are in positive correlation with the fermenter scale, and heat transfer area/working volume, agitation power and impeller diameter/tank diameter are in negative correlation. From these relationship analysis, we have obtained a result indicating that scale up has been mostly done by keeping kia constant while sacrificing larger shearing stress caused by higher impeller tip speed.
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  • YASUHIRO YOSHIMURA, TAKANORI AONO, YUKIKO IKEDA, YOSHISHIGE ENDOU, HIR ...
    2000 Volume 26 Issue 4 Pages 563-568
    Published: July 10, 2000
    Released: July 27, 2010
    JOURNALS FREE ACCESS
    One of the main problems in a hard disc drive is crashing and stiction between the flying slider and the disk. These problems are caused by contamination and condensation of the lubrication oil on the surface of the slider. Stiction can be prevented by treating the flying slider with an oil repellent, that is, a 2- (heptadecafluorooctyl) ethyltrimethoxysilane (FAS) -octadecafluorooctane solution or a octadecafluorooctane solution of 2- (heptadecafluorooctyl) ethyltrimethoxysilane treated by hydrolysis and polymerization (FASI). The effectiveness of the oil repellent treatment was evaluated by measuring the contact angles of mineral oil on the surface of a slider for six cases. The contact angle on the untreated slider was 20°, that on a slider dipped in FAS solution and heated to 393K was 51°, that on a slider dipped in FASI solution and heated to 393K was 68°, that on a slider vapor-deposited with FAS solution at 433K was 80°, that on a slider dipped in FASI solution after ultraviolet radiation (UV) and heated to 393K was 80°, and that on a slider radiated by UV after being dipped in FASI solution was 81°.
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  • KIRO HAYAKAWA, HARUYUKI IGAMI, HIROSHI NABETANI, MITSUTOSHI NAKAJIMA
    2000 Volume 26 Issue 4 Pages 569-574
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    In order to produce highly concentrated apple juice, two stage concentration system which consisted of a low rejection RO membrane and a high rejection RO membrane is developed. We studied the simulation method of the permeate flux and the rejection of clarified apple juice on the low rejection RO membrane and the high rejection RO membrane. In case of RO concentration of clarified apple juice, the permeate flux is lower than the sucrose and glucose solution and the rejection is higher than the sucrose and glucose solution because of fouling of the RO membrane. The influence of the fouling was considered on the simulation of RO concentration of clarified apple juice.
    In the case of the low rejection RO membrane, the permeate flux value and the observed rejection were satisfactorily simulated using the parameters (reflection coefficient, solute permeability and pure water permeability) which were calculated for one experimental condition based on concentration polarization equations and transport equations.
    In the case of the high rejection RO membrane, the permeate flux value is satisfactorily simulated using the correction coefficient of pure water permeability which was calculated for one experimental condition.
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  • YOSHIHIRO IIDA, TOSHIKATSU TSUYUKI, TAKAO MASHIMA, TAKEO TAKASHIMA, KU ...
    2000 Volume 26 Issue 4 Pages 575-580
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    This paper presents a series of experimental results on the passive augmentation technique of boiling heat transfer by supplying solid particles in liquid. A cylindrical heater 0.88mm in diameter is placed in saturated water, in which a lot of mobile particles exist, and the nucleate and film boiling heat transfer characteristics are measured. Particle materials used were alumina, glass and porous alumina, and the diameter ranged from 0.3mm to 2.5mm. Particles are fluidized by the occurrence of boiling without any additive power, and the heat transfer is augmented. The maximum augmentation ratio obtained in this experiment reaches about ten times the heat transfer coeffcient obtained in only liquid. The augmentation ratio is mainly affected by the particle material, diameter, and the height of the particles bed set at no boiling condition. The augmentation mechanism is discussed on the basis of experimental results.
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  • HIROYUKI HAMANO, YASUYUKI EGASHIRA, TOSHINORI KOJIMA
    2000 Volume 26 Issue 4 Pages 581-587
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    It is considered that large-scale afforestation in arid and semi-arid land is one of the most promising countermeasures for fixation of carbon dioxide, which is mainly responsible for the global warming problem. Afforestation of arid land is hindered by water shortages, and requires more effective utilization of limited rainwater. The concept of this study is to evaluate the various countermeasures for constructing water balance system, from different viewpoints of conventional element-technologyoriented measures. In this study, Leonora in Western Australia was selected as a research area, and the infiltration process in the area was analyzed by two kinds of simulation models. Their validity was tested by comparing with the experimental results using glass beads with simple characteristics.
    It was clearly demonstrated that each model has its own problems. Then we evaluated the infiltration rate of precipitated water into Australian specific soil by the model which showed better approximation results to the experiments with glass beads. As a result, it is suggested that the poor permeability of the soil limits plant growth in the Australian specific area.
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  • HISAO INAMI, MITSUKO SAITO, MASAFUMI MOCHIZUKI, KAZUMI SATO, TAKASHI A ...
    2000 Volume 26 Issue 4 Pages 588-595
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    A simulation model for gasification of polyethylene (HDPE) pellet in a fluidized bed with a conical gas distributor is proposed. The model is based on the enthalpy balance and the material balance for the gasification process, assuming the spout, the annulus and the dilute phase are three perfect mixed phases. First a reaction temperature is calculated through the enthalpy balance and then the conversion of HDPE to each gas is calculated by using the reaction temperature.
    The comparison between calculated and experimental values reveals that the model is applicable to predict gas yield in the fluidized bed gasifier with a conical gas distributor. The gasification characteristics such as reaction ratio of the dense phase in the bed and partial combustion ratio of HDPE are examined to clarify the characteristic of gasification of HDPE in the fluidized bed with a conical gas distributor.
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  • YUJI TACHIBANA, YOSHIRO INOUE, YUSHI HIRATA
    2000 Volume 26 Issue 4 Pages 596-603
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    The progress of a mixing pattern is calculated with the knowledge of displacement of fluid particles obtained by integrating the velocity vectors with respect to time. In time-periodic flow, especially the mixing pattern at a discrete time whose interval is equal to multiple periods is able to be estimated with the knowledge of the fluid motion during only one period. In this study, the new discrete model is proposed, and this model enables expression the mixing process in the time-periodic laminar flow. Both the independent variables, time and space, and the dependent variable, concentration, are digitized there. As a result, continuous fluid motion is discretely treated, and the change in mixing pattern is expressed as rotation of a vector representing the mixing pattern. A new algorithm is developed in order to reproduce precisely the fluid motion during one period. In this algorithm, the combinational optimization method based on the neural network theory is used together with the domain reduction method. By use of the discrete model, the progress of mixing pattern in laminar flow is able to be calculated fast and precisely.
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  • TAKESHI YAMANE, EIJI NAKAJIMA, MASAMICHI YOSHIDA, HISASHI MIYASHITA
    2000 Volume 26 Issue 4 Pages 604-608
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Double-diffusive convection in a solutally stratified fluid destabilized by lateral heating and cooling two-layer was studied experimentally. In the range of initial buoyancy ratio N0=0.54-7.17, details of double-diffusive phenomena were investigated by visualization of temperature and flow fields using encapsulated liquid crystals and polystyrene particles.
    On starting the experiment, roll cell convection of two layer was formed by double-diffusion of heat and solute, and the interface broke after thermally quasi-steady state. Attention was focused on the undulation of the interface which occurred before interface breaks. The detailed structure and occurrence condition of undulation were elucidated. It is found that the time when the mixing of the two layer starts is determined by the buoyancy ratio N0 though it changed largely by experimental conditions.
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  • GUILIN PIAO, MOTOHIRO KONDOH, MASATAKA YAMAGUCHI, YOSHINORI ITAYA, RYO ...
    2000 Volume 26 Issue 4 Pages 609-613
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    To explain the combustion behavior of RDF in a fluidized bed, three kinds of model RDF, two kinds of RDF from industrial solid waste (ISW) and two kinds of RDF from municipal solid waste (MSW) were burnt in a bubbling-type fluidized bed combustor. The experimental data of CO, NOx and HCl concentration in the flue gas from the combustor are presented. It is found that much higher CO concentration in the flue gas occurs in the combustion of low density and weak mechanical strength RDF than that of other RDFs, and it can be controlled by secondary air injection. NOx concentration and conversion of fuel-N to NOx from the combustion of larger RDF which contained more metal compounds is far higher than other RDFs. Conversion of fuel-N to NOx is increased with increasing Ca/ (S+0.5Cl) molar ratio because CaO promotes catalytically production of NO. HCl concentration in the flue gas from the combustor decreases with increasing Ca/ (S+0.5Cl) molar ratio. De-hydrochlorination by CaO decreases with increasing combustion temperature.
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  • ISSEI FUJIYOSHI
    2000 Volume 26 Issue 4 Pages 614-616
    Published: July 10, 2000
    Released: March 15, 2010
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    Separation experiments of nickel and cobalt were carried out using a porous glass packed column using methylamine as eluent at 298K. When methylamine concentration is maintained on 1mol/dm3, separation performance is completely accomplished in the pH region from 8 to 8.5, but it is reduced at pH above 8.5 because precipitate of nickel hydroxide is formed. Recovery of cobalt is a minimum of 70% at pH 8.5 when using dilute hydrochloric acid as a post-treatment material, while the recovery is not so much improved for use of dilute nitric acid, and is completely accomplished when using 0.1mol/dm3 EDTA. EDTA is very useful to completely recover cobalt when ammonium chloride is used as eluent. This shows that a slightly soluble cobalt complex similar to pentaammine cobalt (III) complex is formed in the column when methylamine is used as eluent. The two metals are completely separated over the methylamine concentration of 0.5mol/dm3 at pH 8. In this way nickel and cobalt can be separated over wider ranges of concentration when using methylamine than that of ammonium chloride.
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  • MITSUO MATSUMURA, TOSHINORI KOJIMA
    2000 Volume 26 Issue 4 Pages 617-619
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    Incineration of solid wastes is the most effective way to reduce their volume. However, the remaining incineration waste, i. e., ash, often contains high concentration of toxic heavy lead metal. Most of the ash from solid wastes is now disposed of under the regulation of disposal standard of lead, however stricter environmental standards should be applied when the ash is effectively utilized. The lead in the ash should be embedded in the matrix in a stable manner. In the present study, the inhibition of lead elution from incineration ash by addition of phosphate is demonstrated. The effect of calcination temperature between 400-1, 000°C on the lead elution from the ash/phosphate mixture was investigated. The higher the calcination temperature, the lower the elution is. The lead ion concentration in the eluent is much lower than the value estimated from the solubility constant of Pb (OH) 2, and mostly attained environmental standards, which is comparable to or rather smaller than that of PbHPO4. The present result of inhibition of lead elution at high temperature calcination is explained by the conversion from PbHPO4 to Pb3 (PO4) 2. The improvement in the calcination condition will make the inhibition more effective.
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  • YOSHIYUKI BANDO, TAKAYUKI TANAKA, KEIJI YASUDA, MASAAKI NAKAMURA, NOBU ...
    2000 Volume 26 Issue 4 Pages 620-622
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    To disperse oil rapidly and finely in liquid, a bubble column with draft tube installed net (NDT-BC) is proposed. The oil dispersion performance of NDT-BC is compared with those of a standard bubble column (SBC) and a bubble column with draft tube (DT-BC). From these results, NDT-BC is found to have higher performance of oil dispersion than SBC and DT-BC. For NDT-BC the effect of net location and net number on the dispersion performance are examined. An experiment on oil decomposition by using yeast is performed in the three different columns. The oil decomposition performance of NDT-BC is the highest among the three columns.
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  • KOJI TANI, SUSUMU NII, FUMIO KAWAIZUMI, KATSUROKU TAKAHASHI
    2000 Volume 26 Issue 4 Pages 623-625
    Published: July 10, 2000
    Released: March 15, 2010
    JOURNALS FREE ACCESS
    A packed-bed column containing a hydrophobic polymer adsorbent HP-20 was used for removal of oil (toluene) dissolved in aqueous solution. Effects of bed thickness and flow rate are examined. The adsorption equilibrium shows a constant distribution ratio between adsorbent and aqueous solution, indicating physical adsorption. The break-through curve against dimensionless time depended on the ratio of the flow rate to the bed thickness. Theoretical calculation using the mass transfer coefficient in aqueous phase and effective diffusion coefficients in the adsorbent particle generate curves which are in good agreement with the experiments. Regeneration of the adsorbent HP-20 is attained at rather mild condition, while carbon regenerated under the same condition shows only 30% the activity of fresh samples.
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