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Volume 55 (2001)
- Issue 6 Pages 361-
- Issue 5 Pages 268-
- Issue 4 Pages 214-
- Issue 3 Pages 119-
- Issue 2 Pages 69-
- Issue 1 Pages 3-
Volume 55, Issue 6
Displaying 1-6 of 6 articles from this issue
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Akihiro KAWAGUCHI, Takehito KAWASHIMA, Makoto KOGURE, Ichiro TERADA, S ...2001 Volume 55 Issue 6 Pages 361-382
Published: 2001
Released on J-STAGE: February 19, 2013
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Hitoshi SHINDO2001 Volume 55 Issue 6 Pages 383-391
Published: 2001
Released on J-STAGE: February 19, 2013
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Noboru OGATA2001 Volume 55 Issue 6 Pages 392-396
Published: 2001
Released on J-STAGE: February 19, 2013
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Shigetomo AKIHAMA, Kazuo YAMADA2001 Volume 55 Issue 6 Pages 397-407
Published: 2001
Released on J-STAGE: February 19, 2013
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Hideki TSUGE, Yuji TAKAHASHI, Eiji FUJIWARA2001 Volume 55 Issue 6 Pages 408-418
Published: 2001
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSTo utilize magnesium in seawater and fix carbon dioxide in exhausted gases, the direct carbonation method has been used to precipitate basic magnesium carbonate (BMC). BMC particles are used as a filler or anticaking agent for NaC1, which means it is necessary to control the size of BMC particles according to production needs. The aims of this study are to clarify the mechanism of reactive crystallization of BMC in the direct carbonation method, and to control the particle size of BMC.
BMC particles were produced in a gas blowing stirred tank crystallizer through a reaction between carbon dioxide and a suspended aqueous solution of magnesium hydroxide. The particles obtained were analyzed by means of X-ray diffraction and photographs were taken with a scanning electron microscope.
In this study, a mixture of spherical and tabular BMC particles was obtained. Agglomeration between particles was not observed very much during the growth of BMC. The particle size of BMC was influenced by the initial concenration and particle size of magnesium hydroxide, and the reaction temperature. By changing the initial concentration of magnesium hydroxide and the reaction temperature, it was possible to control the particle size of BMC to between 4-9 μm.View full abstractDownload PDF (7421K) -
Yoshitaka YAMAGUCHI, Yuzuru NAKAGUCHI, Munehito KIMURA, Keizo HIRAKI2001 Volume 55 Issue 6 Pages 419-427
Published: 2001
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSSeawater samples were collected in the western North Pacific, the Indian Ocean (Andaman Sea and Bay of Bengal), the Sea of Japan and the Sea of Okhotsk to find levels of dissolved organic carbon (DOC) and to analyze the three-dimensional excitation emission matrix spectrum. The DOC concentrations bellow 1000 m depth showed significantly different distribution. In the Sea of Japan, the mean concentration of DOC below 1000 m was higher, but in the other regions it was approximately the same concentration range. Fluorescent organic matter such as marine humic-like substances constituted 5 to 15% of DOC in the surface layer and 20 to 37% in the deep layer. The results show characteristics of the ocean regions, such as the difference in the nature of dissolved organic matter (DOM) or the existence of different production and decomposition processes of DOM in each ocean region.View full abstractDownload PDF (6181K)
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