Journal of the Clay Science Society of Japan (in Japanese)
Online ISSN : 2186-3563
Print ISSN : 0470-6455
ISSN-L : 0470-6455
Volume 45, Issue 3
Displaying 1-7 of 7 articles from this issue
  • Masato YOSHIDA, Yoshiaki GOTO
    2006 Volume 45 Issue 3 Pages 159-167
    Published: May 29, 2006
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
    Characterization of zeolite Y synthesized in the presence of poly (vinyl alcohol)(PVA) was carried out by using X-ray diffraction technique, SEM, thermal analysis of TG-DTA, and MASS spectroscopy. Homogeneously fine size and round shape crystals were successfully synthesized in a single phase. Existence of polymer led to shorten the induction period of time and an important suggestion was obtained, that is, the solution viscosity caused by polymer gives an advantage to the nucleation of zeolite. It was presumed that the polymer led to a supersaturation of aluminate and silicate ions in the microdomains of polymer aggregates in solution. The results obtained from the thermal analysis and the mass spectroscopy of the fragment ions decomposed from PVA showed that the dehydration reaction of PVA deposited on the surface of zeolite crystal was greatly increased up to about 100°C as compared to the decomposition temperature of PVA homopolymer. A consideration was made that a strong interaction arises due to either the hydrogen bonding between the side chain of hydroxyl groups of the polymer and surface of zeolite or the intermolecular bonding via Na+ion, resulting in the formation of a complex materials of PVA-zeolite.
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  • Chieko NAKAYAMA, Yoshinori TANAKA
    2006 Volume 45 Issue 3 Pages 168-175
    Published: May 29, 2006
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
    The Japanese Ministry of the Environment investigated groundwater quality at sites across the country in 2002. The survey showed that 5.9% of wells exceeded environmental quality standards for nitrogen-nitrate concentration (10mg/L). Ground water with high nitrogen-nitrate concentrations was distributed in areas of diluvial terrace covered by the Kanto loam layer. Kanto loam is a volcanic ash soil containing allophane, which is known to affect the chemical characteristics of this soil type markedly.
    This study discusses the adsorptive features of volcanic ash soils on nitrogen-nitrate using a column test. Several soil samples were obtained from two sites on the Kanto plain. The chemical properties of the volcanic ash soils and pure allophane were subjected to physical analysis before conducting the column test. The column was 40 cm in length and 7 cm in diameter. It was packed with 25 g soil and 2800 g silicate sand and percolated with 0.14 mM nitric acid solution to obtain a break-through curve for nitrogen-nitrate under saturated conditions. The factors of dispersion and retardation were determined from the break-through curve.
    Marked differences were observed between the pure allophane and soil samples. The break-through curve obtained using the pure allophane sample exhibited long tailing-off characteristics after the inflection point at pV=2.0. The retardation factor of the pure allophane sample was also larger than that of other samples. The pH value of the eluant indicated a range from pH5 to pH7 through the column test, while the percolated nitric acid solution had a pH value of 4.2.
    The observed tailing-off characteristics are thought to have been caused by the exchange of H+ from the allophane that is bonded by metal ions. In such instances, the dissociation of the allophane-metallic complex is facilitated by H+ and is associated with an increase in the specific surface area of the allophane sample surface and the generation of a positive charge. Consequently, it is thought that the adsorption of nitrogen-nitrate is accelerated by exposure to positive ions.
    The finding that the adsorption of nitrate by volcanic ash soils was attributed to the H+ on fine allophane particles means that, under low pH conditions, volcanic ash soils exhibit the potential for reducing nitrogen-nitrate in groundwater. Volcanic ash soils could therefore potentially be applied to alleviate nitrate contamination in groundwater.
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  • Masato YOSHIDA, Yoshiaki GOTO
    2006 Volume 45 Issue 3 Pages 176-183
    Published: May 29, 2006
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
    A fine particle of zeolite Y was synthesized hydrothermally in the presence of poly (vinyl alcohol)(PVA) to prepare the zeolite-PVA composite. Studies on the morphological structure of the composite and the interaction forces arising between the two components were carried out by using SEM, FT-IR, X-ray diffraction and BET methods. No extractable homopolymer was found by a repeated extracting with water from the zeolite composites consisting of the polymer in the concentration range from 8 to 26%, but from the 32% polymer content composite, an extractable homopolymer amounting to 4% of the total amount of polymer added to the initial reacting system was also found. The specific surface area and the pore volume of zeolite-PVA composites were significantly decreased with increase of the polymer content. The decreased amounts of both values reached to about 42% at the polymer content of 26%. A similar behavior was also observed even for the blend materials of zeolite and PVA, but only 24% of micropore in the intact zeolite was shielded at the same concentration of the component as described in the above composite. Results obtained by SEM and difference spectrum of FT-IR spectra of the respective components showed that in the composites polymer chains dispersed molecularly in part and hydrogen bonds formed between crystal surface of zeolite and hydroxyl groups of polymer, and further that in blends both of a phase separated polymer and a hydrogen bonded and stabilized polymer on zeolite surface were involved. A structure model of zeolite-PVA composite was proposed and the relationship between the stability of polymer chains in composite and the ratio of the length of polymer chains, L to the thickness of polymer phase on the surface of zeolite particles, ep has been discussed.
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  • Masashi OOKAWA, Yoko ONISHI, Shin-ichi FUKUKAWA, Kei-ichi MATSUMOTO, M ...
    2006 Volume 45 Issue 3 Pages 184-187
    Published: May 29, 2006
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
    Imogolite is tubular clay mineral with typical chemical composition of (OH) 3Al2O3SiOH. Catalytic property of the synthetic imogolite was examined by the isomerization reaction of α-pinene and the oxidation reaction of cyclohexene using hydroperoxide. The acid property of imogolite was not detected by the isomerization reaction of α-pinene. Results of oxidation reaction of cyclohexene indicated that imogolite has the potential of concentration and plays as a field of reaction to increase collision frequency of reactants. Epoxidation of cyclohexene was observed by reaction using imogolite and acetonitrile as solvent.
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  • Takabumi SAKAMOTO, Hirohiko MITO, Atsushi YAMAZAKI, Mayumi JIGE
    2006 Volume 45 Issue 3 Pages 188-199
    Published: May 29, 2006
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
    Sepiolite is one of a magnesium bearing clay minerals having fibrous morphology, and is used as industrial raw material as adsorbent, filler, and so on. Considerable amount of sepiolite have hitherto been imported from U.S.A., Spain, and Turkey. These sepiolites are well-crystallized a-sepiolite showing no visible fibrous morphology. Recently, macroscopically fibrous sepiolite came to import from China. However, in so far as our knowledge, its occurrence and mineralogical properties have not been reported yet.
    In this paper, mode of occurrences and mineralogical properties of macroscopically fibrous sepiolite from four deposits in Henan and Hebei Province, China is reported. In these deposits, sepiolite has been formed as veins crossing dolomitic limestone and crystalline limestone of Precambrian Era developed near the deposits. The XRD study clearly indicates that these minerals are well crystallized a-sepiolite with a small amount of calcite. In some cases, talc and/or tremolite was found as a minor impurity. Mineralogical data such as TG-DTA curves, chemical composition, SEM and TEM, etc. are also presented. The mode of occurrence as well as mineralogical properties of the sepiolite confirm that the sepiolite under consideration is a mineralization product by hydrothermal solution charged with magnesium, silica, etc., moving along the channelways created by fissuring.
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  • Takabumi SAKAMOTO, Takatsugu USHIROUCHI, Mayumi JIGE, Takao ANDO
    2006 Volume 45 Issue 3 Pages 200-210
    Published: May 29, 2006
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
    Palygorskite is a hydrous magnesium and aluminum silicate classified as one of clay minerals. It has a structure similar to sepiolite, however, there is some vacant site in octahedral sheet caused by substitution of Mg ion by Al and Feions. Considerable amount of attapulgite, clayey variety of palygorskite, have hitherto been imported from U.S.A. and used as industrial raw material for adsorbent, filler, catalyst, and so on. Recently, occurrence of macroscopically long fibrous palygorskite in China become known, and several amount of this material has been imported tentatively. However, in so far as our knowledge, its mode of occurrence and the mineralogical properties have not been reported yet.
    In this paper, mode of occurrence and the mineralogical properties of macroscopically long fibrous palygorskite from three deposits in Guizhou Province, China is reported. In these deposits, palygorskite has been formed as veins crossing limestone or calcareous mudstone of Permian or Triassic Period developed around the deposit. XRD study clarify that these minerals are well crystallized palygorskite. Calcite and quartz were frequently detected as impurity. In rare case fluorapatite is also found as impurity. In addition to these impurities, surface of the palygorskite vein is usually contaminated by brown clay come from earth surface through palygorskite veins. Mineralogical data such as TG-DTA curves, chemical composition, SEM and TEM photographs are presented.
    The mode of occurrence as well as mineralogical properties of the palygorskite confirm that the palygorskite under consideration is supergene origin, and directly precipitated from meteoric water rich in magnesium, aluminum and silica with minor amount of iron.
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  • Yoshihiro KUWAHARA
    2006 Volume 45 Issue 3 Pages 211-219
    Published: May 29, 2006
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
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