All issues
Volume 33 (1993 - 199･･･
- Issue 4 Pages 181-
- Issue 3 Pages 130-
- Issue 2 Pages 59-
- Issue 1 Pages 3-
Volume 33, Issue 2
Displaying 1-8 of 8 articles from this issue
- |<
- <
- 1
- >
- >|
-
Effect of Addition of Al IonsMotoharu KAWANO, Katsutoshi TOMITA1993 Volume 33 Issue 2 Pages 59-71
Published: August 31, 1993
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSExperimental alterations of obsidian were performed in 20, 50, and 100ppm of AlCl3 solutions at 150° and 200°C for 1 to 60days. The alteration products were examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray analysis. The surface morphology and composition of obsidian before and after alteration were examined by SEM and X-ray photoelectron spectroscopy (XPS), respectively. The pH-value of solution before reaction is approximately 2.0, and it increased progressively proceeding the dissolution of obsidian. The alteration products appeared in this reaction system were strongly dependent on pH-values of solutions. XRD and TEM showed that boehmite, spherical kaolinite and precursor of smectite exhibiting fibrous habit were mainly formed in acidic solutions. However, smectite appeared as predominant reaction product in solutions at pH>5.0, and the spherical kaolinite began to decompose at that pH range. XPS indicated that Al-rich layer was formed on the surface of obsidian by cation exchange reaction between Si and Al in solution during the initial dissolution stage. The Al-rich layer began to dissolve into the solution with increasing pH of solutions.View full abstractDownload PDF (16389K) -
Masahiro SUGIURA, Kazuhiro FUKUMOTO1993 Volume 33 Issue 2 Pages 72-80
Published: August 31, 1993
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSThe adsorption-desorption of ammonia and acetaldehyde by sepiolite and coconut-shell active carbon in ambient air having various relative humidities (RH) at 25°C and 50°C was studied to develop adsorbents for ammonia and acetaldehyde.
The absolute amount of reversible adsorption for ammonia by sepiolite in ambient air having 25-39% RH at 25°C and 50°C, was the same as that in ambient air having 91% RH at 25°C and was extremely larger than that by the carbon in ambient air having 31-33% RH at 25°C. The amount of ammonia adsorbed by the carbon in ambient air having 25% RH at 50°C was about 3.5 times larger than that in ambient air having 12% RH at 50°C. These facts indicate that sepiolite can be used as an adsorbent for ammonia regardless of RH in ambient air, and that the carbon can be used only at high RH.
The absolute amount of reversible adsorption for acetaldehyde by the carbon was about 3times larger than that by sepiolite in ambient air having 30-90% RH at 25°C and 50°C. In ambient air having 90% RH at 25°C, in paticular, acetaldehyde was purged from the sepiolite which previously adsorbed it, although it was not purged from the carbon which adsorbed it previously. These facts indicate that the carbon can be used as an adsorbent for acetaldehyde regardless of RH in ambient air, and that sepiolite can be used only at relatively low RH.View full abstractDownload PDF (1115K) -
Studies on the Influence of Acid Rain on Rocks and Minerals (Part 2)Shoichi KOBAYASHI, Takabumi SAKAMOTO, Satoru KAKITANI1993 Volume 33 Issue 2 Pages 81-91
Published: August 31, 1993
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSAn artificial chemical weathering of a polished plate of granite from Kitagi, Okayama Prefecture, Japan was conducted using a Soxhlet extraction apparatus with distilled water and HNO3 solution of pH4 at 50°C for a different period of time up to 189 days. The granite was composed mainly of quartz, plagioclase (Ab86An12Or2), alkali feldspar (Or92Ab8) and biotite. The results showed the release of elements and the degree of weathering of minerals as a function of leaching time. Among the all minerals, biotite showed the higher chemical weathering that was enhanced by the HNO3 solution.
The chemistry of the surface of each mineral shows a characteristic change during the chemical weathering as follows: 1) The ratios (Mg+Fe+Mn+Cr)/Al in the octahedral sheet and (K+Na+Ca)/(Total Al) in the interlayer of biotite decrease with the increase of leaching time, but the ratio (Si+Ti)/Al in the tetrahedral sheet is not changed; 2) The tatio (Na+Ca+K)/Al for plagioclase decreases with the increase of leaching time.
Smectite, containing a small amount of iron, was developed from the alteration of plagioclase during the chemical weathering by the HNO3 solution.View full abstractDownload PDF (10034K) -
Shusaku YAO, Akane ABE, Hideyuki ITO1993 Volume 33 Issue 2 Pages 92-101
Published: August 31, 1993
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSPale reddish-brown tinted Ruby Muscovite, from India has been studied in contrast to colorless Muscovite, by means of optical absorption spectroscopy and EDS-XRF. Absorption curve was measured over the range 350 to 1300nm. Tinted Muscovite indicates the distinctive absorption bands, mainly assigned to Fe3+ ions in the range of 440-550nm, while a colorless Muscovite indicates one band assigned to Fe2+ ion, in the range of 750-1000nm. Concentration of Fe3+ or Fe2+ ions are obtained, from total Fe confirmed by EDSXRF and extinction coefficients of absorption band at 508 or 862nm. It is concluded that reddish-brown color is due to the presence of Fe3+ ions, and not to Mn or Ti ions.View full abstractDownload PDF (1234K) -
Naoto MATSUE, Teruo HENMI1993 Volume 33 Issue 2 Pages 102-106
Published: August 31, 1993
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSAllophane has a morphology of aggregates composed of fine hollow spherules with the diameter of 3.5-5.0nm. The compositions of the wall of hollow spherules are in a range about 0.5 to 1.0 in terms of Si/Al atomic ratio. The measured surface acidity was higher in strength for allophane with higher Si/Al atomic ratio than for that with lower ratio. It was difficult for allophane to know detailed mechanism of its surface acid phenomenon by means of only experimental methods.
In this study, molecular orbital calculation was performed using the PM3 semi-empirical SCF-MO method for the strucure of allophane to elucidate theoretically its surface acid properties in the stage of as deep as electron level. The calculation showed that silanol OH groups could more strongly interact with aluminium atoms or aluminol groups in allophane strucure having higher Si/Al atomic ratio than in that having lower ratio. Because the interaction facilitates the dissociation of proton from silanol OH groups, the greater the degree of interaction, the stronger the surface acidity of allohane.View full abstractDownload PDF (610K) -
Nozomu OTSUKA, Tsuyoshi HAYASHI, Kazuhito OKANISHI, Shoji KUBODERA1993 Volume 33 Issue 2 Pages 107-114
Published: August 31, 1993
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSOzone was used for purification of the pyrophyllitic roseki clay contaminated with pyrite impurities. The greater part of pyrite particles were removed in advance by froth flotation from the crude slurry prepared with special attention to avoid the excess size reduction of pyrite. Then the remaining pyrite in the clay was oxidized with ozone, resulting in the formation of iron sulfate and sulfuric acid. As the oxidation reaction occurs at the interface of pyrite and the sorrounding solution, the rate of iron dissolution depends on the specific surface area of pyrite. The pyrite in the clay fractions with particle size under 2μm existed almost in the form of isolated particles and is found to be dissolved with high efficiency. In contrast, a considerable amount of pyrite in the clay fractions with coarse particle size is encapsulated in the roseki clay particles. Consequently, the rate of iron dissolution from the pyrite is low, resulting in the decrease of deironation efficiency. On the other hand, the deironation efficiency was also influenced by the pH condition of the clay slurries and tends to become higher as the pH value is lower due to the increase in the solubility of iron ions. However, since the clay structure degrades in a low pH region, the pH conditions are appropriate for the deironation treatment of the roseki clay are around pH2.5-3 at the start and around pH2-2.5 at the final.View full abstractDownload PDF (929K) -
Tsuyoshi HAYASHI, Nozomu OTSUKA, Mitsuhiro KASAI, Sigeru HORIE1993 Volume 33 Issue 2 Pages 115-120
Published: August 31, 1993
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSClay fractions were separated from the flotation tailings of the ‘Kuroko’ metallic ore and were refined by eliminating fine sulfide impurities employing liquid-liquid extraction. The solid classified in advance by hydrocyclone under the size about 10μm from the tailings was strongly flocculated due to the existance of concentrators plus a large amount of soluble salts and secondary formed minerals arizing from the oxidation of sulfide minerals during ore dressing. Therefore the washing pretreatment using chelating reagent and reductant was adopted to attain good dispersion of the slurry for classification of clay under 2μm. Heavy metal impurities in the ‘Kuroko’ clays, which are composed mainly of sericite accompanied by a small quantity of chlorite, were eliminated in the order of Cu>Zn>Pb by oil-extraction of those sulfide particles from the well dispersed clay slurry. Although the residual quantity of Cu in the refined clays is found to be around 30ppm, that of Zn and Pb is higher in proportion to the oxidized degree of the sulfide minerals. The effect of the oxidation is appreciable markedly in the case of Pb that exists as PbSO4 by oxidation. It is recommended that for efficient elimination of fine sulfide particles from the clay slurry, the clay fraction in the raw ore should be separated before the conventional froth flotation which promotes the oxidation of sulfide minerals.View full abstractDownload PDF (745K) -
1993 Volume 33 Issue 2 Pages 123
Published: 1993
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSDownload PDF (50K)
- |<
- <
- 1
- >
- >|