All issues
Volume 38, Issue 1
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
-
Noriko SHINOZUKA, Shigeo HAYANO1984 Volume 38 Issue 1 Pages 3-13
Published: 1984
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSDownload PDF (7767K) -
Noboru OGATA1984 Volume 38 Issue 1 Pages 14-27
Published: 1984
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSDownload PDF (11590K) -
Masao NOMURA, Makoto OKAMOTO, Hidetake KAKIHANA1984 Volume 38 Issue 1 Pages 28-33
Published: 1984
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSA rapid method using an ICP emission spectrophotometer with simple pretreatments was applied to determine the boron content of surface seawater samples collected (1) in the northwest part of the Pacific Ocean and (2) at the coast of Satsuma Iwo-jima; the results were 4.6±0.2μg/ml for both samples. The boron content of sample (1) was also determined more precisely as 4.66±0.02μg/ml by the isotope dilution method. The chlorosity of this sample was 19.85g/l, which corresponds to 35 % salinity. Determinations of boron isotopic ratios (11B/10B) were carried out on the two seawater samples. Their ratios were 4.200 and 4.207, respectively, showing a good agreement within an error of 0.2%.View full abstractDownload PDF (3211K) -
Kenkichi IZUMI, Akira YAMADA1984 Volume 38 Issue 1 Pages 34-43
Published: 1984
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSScale formation on the surface of heat transfer tubes is one of the most important problems in distillation-type desalination plants. Scale, which is formed by the deposition of the less soluble salts in sea water, consists of two types: calcium sulfate scale, of which the chief constituent is calcium sulfate, and alkaline scale, which consists of calcium carbonate and magnesium hydroxide.
Calcium sulfate scaling can be prevented by controlling the temperature and concentration factor of the brine within the precipitation limits.
The formation of alkaline scale is related to the chemical equilibrium of the carbonates in the brine. In a submerged-tube-type evaporator, the brine evaporates on the heat transfer surfaces of the tubes and the gases dissolved in the brine are freely removed from the brine. Alkaline scale forms as a result of thermal decomposition of bicarbonates to carbonates and carbon dioxide and of hydrolysis of carbonates to hydroxyl ions and carbon dioxide. However, in a multi-stage flash evaporator, there is no evaporation on the heat transfer surface and no evolution of carbon dioxide from the brine by applying pressure to the brine, so the mechanism of formation on the basis of the dissociative equilibrium of the carbonates was applied to alkaline scaling.
Material balance of alkaline scale in a multi-stage flash evaporator was calculated by the scaling mechanism proposed. Based on the results obtained, as well as data on scale deposition obtained with a 100 m3/day, 10-stage flash evaporator with pH control method for scale prevention, the appropriateness of the scaling mechanism was shown. As the dissociative reaction rate of the carbonates in brine is not so fast, material balance of alkaline scale can be calculated considering the transitional response of the carbonates.View full abstractDownload PDF (6447K) -
Shoji KIMURA, Tsuyoshi NOMURA1984 Volume 38 Issue 1 Pages 44-49
Published: 1984
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSThe desalination of sea water by pervaporation using RO membrane and porous PTFE membrane was examined. Results showed that product flux was well proportioned to vapor pressure difference of solution, and product water purity tended to increase with temperature in both membranes. For examples, product flux of 4.0kg/m2·hr, purity of 2.0μS/cm at 25°C and 20kg/m2·hr, 1.5μS/cm at 50°C, respectively, was obtained in RO membrane. Furthermore, desalination was tried by thermo-pervaporation using porous PTFE membrane, and it also produced almost the same results.View full abstractDownload PDF (3706K) -
Taitiro FUJINAGA, Tooru KUWAMOTO, Eiichiro NAKAYAMA, Kenji ISSHIKI1984 Volume 38 Issue 1 Pages 50-55
Published: 1984
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSMagnesium hydroxide precipitate depositing from alkalized seawater was used as an adsorbent for the extraction of uranium from seawater. Calcium hydroxide was a suitable alkali because the adsorption of uranium was enhanced int he presence of calcium ion. Uranium was adsorbed quantitatively with magnesium hydroxide precipitate when an adequate amount of calcium hydroxide was added to precipitate 80 to 90% of magnesium ion in seawater. More than 80% of adsorbed uranium was eluted from the precipitate with 1 to 3 M ammonium carbonate solution, in which the precipitate was hardly dissolved at all. With this method about 11 mg of uranium was collected as uranyl salt from 6,000 l of natural seawater. The recovery throughout all processes was about 70%.View full abstractDownload PDF (4072K) -
Tsuyoshi HIROTA1984 Volume 38 Issue 1 Pages 56-66
Published: 1984
Released on J-STAGE: February 19, 2013
JOURNAL FREE ACCESSDownload PDF (6012K)
- |<
- <
- 1
- >
- >|