To research the adsorption process of uranium from sea water by aluminium-activated carbon composite adsorbent (C-Al-OH), the authors examined the effects of temperature, pH and carbonate ion concentration of the solution upon the adsorption of uranium, using sodium chloride solution and natural sea water.
The continued mixing of the solution for the duration of two to four hours was required to attain the apparent equilibrium of adsorption. The adsorption velocity at an early stage and the uptake of uranium at the final stage showed an increase in proportion to a rise in the adsorption temperature. In the experiment of adsorption for which sodium chloride solution was used, the linear relationship between, the logarithm of the distribution coefficient (K_d) and the pH of the solution was recognized. The uptake of the uranium from the solution at the pH of 12 increased. as the carbonate ion concentration in the solution decreased. The uranyl ion in the natural sea water was assumed to be uranyl carbonate complex ion (UO₂(CO₃)₃^4-). As the result of the calculation conducted by using the formation constants for uranyl complexes in literature, it was. found that uranyl hydroxo complex ion (UO₂(OH)₃^-) increased in line with a decrease of the carbonate ion concentration in the solution.
The above results of the experiment suggested that the adsorption of uranium by the adsorbent.(C-Al-OH) was cationic adsorption or hydrolysis adsorption being related with the active proton on the surface of the adsorbent.

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To study the relationship between the quality of Chinese solar salt and the composition of mother liquid in concentrating and crystallizing ponds, an analysis was conducted on the brine of concentrating ponds, the mother liquid of crystallizing ponds, and the solar salt taken from Tangku Salt Field in China in May, 1975. The results of the analysis were as follows:
1. The weight ratio of Na/Mg of the brine and mother liquid was eight from the stage of sea water to the stage of the second concentrating pond, but it began to decrease at the middle stage of the second concentrating pond and came down to three at the stage of the crystallizing pond. In addition, the chemical composition of the solution differed from the concentrating process line of sea water. This showed that the mother liquid circulated between the second concentrating pond and the crystallizing pond.
2. When the total impurities of the solar salt taken for the current analysis were compared with those of the solar salt mentioned in previous papers, the content of sodium chloride was 1.5% more than before, while the content of water and insoluble matters was 1.0% and 0.2% less, respectively.
3. As the result of the comparison made on the impurities in the crystals of the solar salt between the current and previous analyses, the content of impurities excluding potassium ions in the crystals was 20-50% of the previous case. Judging from the contents of the total impurities and of the impurities in the crystals, the solar salt samples taken for the current analysis were of better quality.
4. The calculated concentration of magnesium ions of the solar salt was higher than that of the mother liquid in the crystallizing pond. This suggested that in the early part of the growth-stage the crystals of the solar salt grew in the more-concentrated mother liquid being contained in the crystals, but in the later part of the growth-stage they were placed in the less-concentrated mother liquid attaching to the surface of the crystals.
5. To make a comparison on the impurities of the outer and the inner sides of the crystals, 10-20mm polycrystals of the solar salt were crushed into 4-5mm unit-crystals, and about 80% of the total was resolved in water and analyzed. The amount of the impurities of the outer side was 4-6 times more in potassium ions and 6-12 times more in magnesium ions than the inner side.
6. The total water content of the solar salt was 2.3g/100g, of which 11%(0.26g/100g) was in the cavities of the crystals, 30%(0.67g/100g) among 10-20mm polycrystals (aggregates of 4-5mm unit-crystals), and 59%(1.37g/100g) on the surface of the crystals.

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As the result of the analysis conducted on the sea water and the sea-bottom sediments at the several points of Tokyo Bay affected by the polluted rivers flowing into it, and of the incubation tests of the sediments, the following were made clear concerning sulfate reducing bacteria.
1. The concentrations of organic matter and nutrient salts were higher in the surface portion of the sea than in the bottom portion. This fact indicated that the polluted water from the rivers spreaded widely in the surface of the sea water without having mingled with the sea water because of the difference between the sea water and polluted water densities. Especially, quite a number of sulfate reducing bacteria was observed in the surface of the sea water where the polluted water flew into directly. This was because the sulfate reducing bacteria having grown in the bottom sediments near the estuaries were carried by the flowing water.
2. In such an area as the inner part of Tokyo Bay, sulfate reducing bacteria may grow even in the sea water. In that case, the concentration of organic matter and the temperature affect the number of bacteria.
3. The sulfate reducing bacteria found in the sea seemed to have originated from fresh water, because they were more active to a fresh-water medium than to a sea-water medium.
4. Sulfate reducing bacteria grow actively in the bottom sediment. The concentration of organic matter had little influence on the number of bacteria in the bottom sediment, but the temperature had an influence because the number of bacteria increased in summer and decreased in winter.
5. There was a good correlation between the concentration of sulfide and the concentration of organic matter (ignition loss) in the bottom sediment.
6 The anaerobic incubation tests of the bottom sediment controlled at 37°C and pH7, resulted in a new generation of hydrogen sulfide. The generation rate in case hydrogen gas was bubbled was 20 times more than that in case of nitrogen gas.

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Oka, one of the above-mentioned authors reported in his previous paper on the graphical calculations for isothermal evaporation of four kinds of ionic brines by using Jdnecke type triangular coordinated diagrams of 5-component system Na⁺, K⁺, Mg²⁺, Ca²⁺ Cl^--H₂O saturated with NaCl at 110°C, 70°C, 45°C. As the most practical result, it was found that the best NaCl yield of ionic brine could be obtained by doing the evaporation just upto the saturation point of KCl. The hot mother liquor separated from such concentrated slurry was saturated at the same time with NaCl and KCl. When it was cooled, therefore, salt crystals must have been depositted.
In the present paper, the authors again made graphical calculations as to how much water be evaporated by evaporation at 110°C under the best conditions, how much NaCl be obtained, and what kinds of salts come out by cooling the separated hot mother liquors to 25°C and how much of them be obtained. The phase diagrams of D'Ans type of 5-component system saturated with NaCl were used for these calculations, because the concentrations of the components could be read directly.
Only a part of the diagrams for the 5-component system which was requisite for the calculations was drawn on the common axes; namely, lines for the bivariant systems, NaCl-KCl-Carnallite-H₂O (SX), NaCl-Carnallite-Bischofite-H₂O (RY), and a monovariant system NaCl-KCl-H₂O (E) as shown in Tables 1 and 2, and Fig.-1.
By evaporation of ionic brine at 110°C, the mother liquor saturated with KCl must be on the triangle E₁S₁X₁. By cooling the mother liquor, the kind of salts to deposit can be determined by the position of point on the part of 25°Cdiagram. Such computations were done in Fig.-1, and the triangle E₁S₁X₁ was devided into three fields; namely, II, V and III, by two straight lines gh and ij. The mother liquor in field II deposited NaCl and KCl by being cooled to 25°C, and it lay on the triangle E₂S₂X₂. The hot mother liquor in field V deposited NaCl, and carnallite simultaneously by being cooled to 25°C, and the cold mother liquor lay on the line S₂X₂. And, the hot mother liquor in field III deposited NaCl and carnallite simultaneously, and the cold mother liquor lay on the quadrangle S₂X₂Y₂R₂.
When four ionic brines A, B, D and E (Table-5) were evaporated at 110°C to the saturation point of KCl, the mother liquors for A and B lay in field II, and those for D and E lay in field V. The graphical calculation for mother liquor A was shown in Fig.-2, and for D in Fig.-3.
For such calculations, the final concentrations of KCl, MgCl₂ and CaCl₂ could be read directly from the diagrams. But the concentration, of NaCl could not be read directly, and so it was interpolated with Fig.-4 on the assumption that the concentration of NaCl on a straight line changed linearly.
The results of these calculations were verified: The results of evaporations were compared with those in the previous paper, and the crystal depositions by cooling were verified with semi-quantitative experiments. The authors believe from these verifications that the method of calculations is a reliable one.

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In authors' previous paper, the authors proposed the estimating equation for the limiting current density Eq.(1), which was one of the important factors in operating the electrodialytic equipment with ion exchange membranes.
The aim of this paper is to make clear the effect of temperature on the limiting current density. From the experimental work for the electrodialytic stack without a spacer, it was found that the limiting current density at any temperature could be estimated by using Eq.(1).
Also, the convenient relative equation Eq.(3) between the limiting current density and the temperature was proposed.

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[in Japanese]

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