Bulletin of the Society of Sea Water Science, Japan
Online ISSN : 2185-9213
Print ISSN : 0369-4550
ISSN-L : 0369-4550
Volume 64, Issue 5
Displaying 1-11 of 11 articles from this issue
Greeing
Special Issue : “A Study of the Seawater of West Japan (2)”
Review
  • Mitsuru Higa, Megumi Nishimura
    2010 Volume 64 Issue 5 Pages 244-249
    Published: October 01, 2010
    Released on J-STAGE: August 10, 2011
    JOURNAL FREE ACCESS
    Ion-exchange membranes with a semi-interpenetrating network structure were prepared by blending poly (vinyl alcohol) (PVA) and polyelectrolytes. The membranes obtained were physically cross-linked by annealing them at various temperatures and chemically cross-linked by reaction with glutaraldehyde aqueous solutions to obtain heterogeneously cross-linked structure in the membrane. The charge density of the membrane increased with increasing polyelectrolyte content, annealing temperatures and the concentration of a cross-linker agent.
    The permeability coefficient of methanol through the PVA-based cation-exchange membrane was 30 times lower than that of Nafion®117 under the same conditions. The PVA based membrane had about 3 times higher proton permselectivity than Nafion®117.
    A bipolar membrane and a charge mosaic membrane were also prepared by pasting PVA-based cation-exchange layers and anion-exchange layers. The permselectivity for salt through the PVA-based charge mosaic membranes was more than 30 times higher than the charge mosaic membrane Desalton® (Tosoh Co. Ltd.)
    The PVA based ion-exchange membranes can be prepared more cheaply and have more anti-fouling properties than commercially-available ion-exchange membranes prepared from styrene- divinylbenzene based resin. Hence, the PVA based membranes will have potential application to the desalination of salt water or purification of biochemical materials or food additives.
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Commentary
Original Papers
  • Yasushi Noda, Takuya Asada, Kensei Kobayashi
    2010 Volume 64 Issue 5 Pages 275-283
    Published: October 01, 2010
    Released on J-STAGE: August 10, 2011
    JOURNAL FREE ACCESS
    A multiresidue analytical method based on solid phase extraction with LC/MS was developed for agricultural chemicals in edible salts. For the extraction of agricultural chemicals from salt samples, a sample solution prepared at pH 3.5 was passed through a styrene-divinylbenzene, methacrylate copolymer cartridge that was preconditioned with 10% EDTA solution. The recovery rate was more than 70%, and the relative standard deviations were lower than 20%. The solvent of the eluate was changed from acetonitrile to a mixture of 80% water and acetonitrile, which resulted in sharp peaks in LC chromatograms. Benomyls were degraded during the extraction procedure, but they could be quantified as total benomyls and their degraded chemicals. The quantification limit for all the agricultural chemicals tested in edible salts was less than 0.01 mg/kg. Thirty-three agricultural chemicals could be analyzed by the present LC/MS method. If both the GC/MS method reported previously and the present LC/MS method were applied to the 162 agricultural chemicals selected by the Salt Industry Center of Japan and found in edible salts, 128 agricultural chemicals could be analyzed.
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  • —Construction and Performance of a Quintuple-Effect Concentrator—
    Takehiro Nosoko, Kazumasa Ameku, Wataru Oshikawa, Atsushi Nakano
    2010 Volume 64 Issue 5 Pages 284-290
    Published: October 01, 2010
    Released on J-STAGE: August 10, 2011
    JOURNAL FREE ACCESS
    A quintuple-effect seawater concentrator consisting of four distilling layers and a top evaporating fabric was constructed and its performance was tested. In this concentrator, the bottom surface of 1 m×2 m is heated up to 100°C, while the top surface was cooled in 23°C air by free convection accompanied by evaporation. Each distilling layer was constructed with a mesh spacer of plastic 5mm thick placed between an evaporating fabric and a condensing fabric, and in this construction, it was found that no condensate leaked to the evaporating fabric and no concentrate leaked to the condensing fabric. The total evaporation in this concentrator was 15.4 kg/h, and it is suggested that the evaporation increases as the area of the mesh spacer through which the vapor diffuses is increased and as the cooling on the top surface is increased. The separating plate between the distilling layers is a silicone-coated, hot-dip zinc-coated steel sheet. While this plate was kept in contact with the seawater-soaked evaporating fabric in this test, it is not in rust.
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  • Akihiro Koga, Yasushi Noda
    2010 Volume 64 Issue 5 Pages 291-296
    Published: October 01, 2010
    Released on J-STAGE: August 10, 2011
    JOURNAL FREE ACCESS
    To clarify the form of arsenic contained in common salt, the application of high-pressure liquid chromatography with inductively coupled plasma mass spectrometry (HPLC/ICP-MS) was examined. The effects of dilution and sodium chloride concentration of the eluent on the chromatogram were studied. As and As both inorganic substances and arsenobetaine, an organic substance, were completely separated, and the amount of each of these substances in common salt was clarified. In 0.2 g/100mL sodium chloride solution, the measurement limitation was 0.5 μg/L. Therefore, the measurement limitation was 0.25 mg/L for common salt. It was found that arsenic was chiefly included as the inorganic substance, As by analysis using this method for common salts, by which arsenic was detected in our past study. On the other hand, when the arsenic compounds were heated above 200°C, arsenic was confirmed to change into As. The possible change of arsenic into As was suggested to occur during heating processes such as drying when arsenic compounds are mixed with the raw material of salt.
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  • Motoshi Kunugi, Michiaki Matsumoto, Kazuo Kondo
    2010 Volume 64 Issue 5 Pages 297-304
    Published: October 01, 2010
    Released on J-STAGE: August 10, 2011
    JOURNAL FREE ACCESS
    In recent years, global warning due to increase in CO2 concentration in the air is feared. To solve this problem, the use of biomass has been considered. In particular, we have paid attention to a microalgae which can photosynthesize. The microalgae not only remove CO2 but also transform CO2 into useful organic materials.
    The purpose of this study is to construct the process where CO2 removal and useful material production by the microalgae, Haematococcus pluvialis, were performed at the same time.
    When the air containing CO2 was used, the microalgae photosynthesis ability was heightened, and the growth of the microalgae was much promoted than those when using only air. Along with this, useful material production was promoted. When CO2 concentration in the air was increased highly, the growth of the microalgae was restrained. As the result, the optimum condition of CO2 concentration in the air was 5% from the view point of both useful materials production and microalgae growth.
    When the flow rate was increased, the culture time could be shortened. However when the flow rate was increased too highly, the growth of the microalgae was restrained. From this result, the optimum condition of the flow rate was found to be 150 cm3/min.
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  • Tetsushi Fuchiwaki, Takuya Asada, Naohito Yoshikawa, Masami Hasegawa
    2010 Volume 64 Issue 5 Pages 305-312
    Published: October 01, 2010
    Released on J-STAGE: August 10, 2011
    JOURNAL FREE ACCESS
    To establish a method of determining the optimal operation conditions of the high-rate filtration system , the pressure loss of the system over time was simulated using the concentration of a added flocculant, filtration rate, and the height of a filter layer in a cylindrical column as parameters.
    The optimal concentration of the flocculant to be added to the high-rate filtration system depends on the type and amount of suspended material. It was clarified that the amount of trapped aggregate flock and pressure loss in the system have a linear relationship when the appropriate flocculant concentration is selected.
    For various seawater samples with different types and amounts of suspended material, experiments were carried out by changing flocculant concentration, filtration rate, and filter layer height. A method of simulating pressure loss over time was established by applying the filtration characteristics obtained from the experimental results to a basic equation of pressure loss in cake filtration. This method enabled the high-accuracy estimation of the pressure loss over time and the simulation of a decrease in filtration rate due to the trapped aggregate flock and that in filter layer height.
    Using the established method, we determined flocculant concentration, filtration rate, and filter layer height such that the filtration system ensured a fouling index (FI), an index of filtered water quality, of 3.5 or lower during the filtration for 11 hours or longer as the desired performance, and carried out demonstration tests in two salt production plants with different amounts of suspended material. In these tests, the above performance was obained, and the validity of our simulation method was verified.
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