In Japan, common salt is made by concentrating sea water by electrodialysis method and evaporating the concentrated sea water (ionic brine) in vacuum pans. As its characteristic, ionic brine is composed of chloride solution containing a negligible amount of SO₄^2-. Therefore, the treatment of ionic brine such as its evaporation and so forth can be graphically calculated on the diagrams of the five component system; Na⁺, K⁺, Mg²⁺, Ca²⁺Cl^--H₂O.
In the previous paper, the author reported the method of graphical calculation for the evaporation of four kinds of ionic brines at three different temperatures by using the Janecke type triangular coordinated phase diagrams of the five component system saturated with NaCl, and concluded that the best NaCl yield could be obtained by evaporation to the point of KC1 saturation.
In this paper, the author tried to get some usefull applications to the salt manufacturing industry in our country.
(1) At first, the graphical calculations were made for the evaporation of four kinds of ionic brines (Table-1), at eight different temperatures, namely 0°C, 25°C, 35°C, 45°C, 50°C, 70°C, 75°C and 110°C (Fig.-1) to the saturation point of KCl. From the calculations, it was found that the NaCl yields brines of depended solely on the temperature of evaporation, and not on the brine composition. The higher temperatures gave better NaCl yields. The rate of evaporations also depended on the temperatures. In this case, however, the compositions of brines seemed to have some effects (Fig.-2).
(2) The NaCl yield y was shown by the following empirical formura:y_t=85.4+6.3log t(Fig.-3).
(3) In the salt making procedure, the temperature of separating salt crystals by centrifuging salt slurry is very important. Because the mother liquor (or bittern) needs to have been just saturated with KC1. Therefore, a lower temperature of centrifuging gave a lower NaCI yield, and a smaller rate of evaporation.
(4) Then, the ratios (NaCl obtained/H₂O evaporated) were calculated. These ratios depended solely on the compositions of brines, and not on the temperatures. Moreover, the ratios were nearly equal to the ratios of NaCl/H₂O in the compositions of brines. The ratio means the amount of NaCl obtainable by the evaporation of a unit amount of water. In another word, it means the energy efficiency of evaporation.
(5) From the graphical calculation, it was found out that the ratios NaCl/H₂O (y) could be calculated by the following empirical equation from NaCl concentrations in brines (x):y=-0.014+0.00115x (Fig.-5).
(6) To show some examples, monthly values of NaCl/H₂O ratios of ionic brines in ten working electrodyalitic factories were shown in the graph (Fig.-6).

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イオン交換膜法電気透析による, 海水の脱塩における溶存物質の透析挙動について研究し, あわせて脱塩水の化学組成と河川水などの組成と比較を試みて次の諸結果を得た.
(i) 海水の溶存主成分のうち大部分は透析されやすく, ストロンチウムも, 他のアルカリ土類金属イオンとほぼ類似の傾向を示すと推定した, しかしホウ素およびケイ素は, ほとんど透析されない. これは, おそらくそれぞれ無荷電のB(OH)₃およびSi(OH)₄なる化学種として存在しているものと考えた.
(ii) 海水中の微量重金属はバナジウムを除いて, 大部分はその傾向に差異はあっても透析される. 鉛は初期は減少するが, 脱塩がすすむとともに透析されにくくなる. また, 銅, 亜鉛, カドミウム等の溶存形が錯体などの形であるか否かは明らかではない. モリブデンは初期はほとんど透析されず, 脱塩率89%あたりから急激に減少する. しかし, バナジウムは, ほとんど透析されずに残留する. これは,[VO₂(OH)₂]^2-などが陽イオンとのイオン対のままであるか, あるいは [H₂V₄O₁₃]^4-のような重合イオン, またはそのイオン対としての溶存のいずれかによって透析されにくいものと推定した.
(iii) 炭水化物ならびに, これをも含めたCOD物質は, 予想されるとおり脱塩水中に残留した.
(iv) 塩素イオン200mg/l前後の脱塩水について, その組成を同じ濃度の希釈海水ならびに, 河川水組成と比較を試みた結果, 脱塩水中には多量のホウ素が残留すること, ならびに有毒物質のバナジウムが同様に残留する傾向がある点で, 飲料水としては衛生上の問題があるものと思われた.

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