Effects of coexisted ions other than Na+ in sea water and brine on specific resistance were measured for two kinds of commercial membranes. 1. In case of cation membrane, its specific resistance was increased by adsorption of magnesium and calcium ions, but it was decreased by potassium. The specific resistance of the membrane in sea water was about two times as compared with that in 0.5N sodium chloride solution. With an increase in the concentration of external solution, the resistance became lower because of an increase in the amount of Donnan's absorption. 2. In case of anion membrane, its specific resistance was increased by adsorption of sulfate ion, but the effect of sulfate ion was small. 3. The specific resistance of the cation membrane in the solution of multi-component systems such as sea water and brine approximated to the summarized parallel resistance of the partitioned membrane of component ion type, the area of which was equal to the product of the total membrane area and the absorption factor of each component ion. 4. In case of the cation membrane in sea water and brine, absorption factors of calcium and magnesium ion were fairly greater than that of sodium ion. 5. The amount of ion of Donnan's absorption showed a lower value as compared with its theoretical value when the concentration of the external solution was above 1N. This phenomenon was considered to be due largely to the shrinking effect of the membrane.
Lithium contained in sea water was determined by atomic-absorption spectrophotometry by using air-hydrogen flame. Sodium, potassium and chloride ions so significantly interfered the absorption of lithium that the precise result could not be obtained even when the calibration curve was constructed by addition of lithium standards. Lithium was separated from other alkali metals by extracting the chloride salt with iso-amyl alcohol, and the resulting organic solution was sprayed into the flame. The sensitivity of this procedure was comparatively low, but the reproducibility was much better than in case aqueous solution was used. Thus, more accurate results were obtained. Some sea-water samples were analized, and their lithium content was found to be about 140μg/1 in coastal and 170μg/1 in open sea water.
The authors have made a study on the behaviors of minor components in the process of concentrating sea water. The present study dealt with the behaviors of zinc and cobalt ions by using radioactive tracer 65Zn and 60Co. Zinc and cobalt ions behaved in the similar manner, and indicated a greater loss from the solution evaporated at higher temperature. In contrast with strontium, calcium and phosphate, however, they were never rapidly lost in the final stage of concentration. Therefore, 30-50% of them remained in the solution even after 95% of sea water was evaporated. Most of the zinc and cobalt deposited were distributed into insoluble gypsum deposit, and almost none of them were contained in soluble salt. Zinc and cobalt in sea water were determined spectrophotometrically with zincone and nitroso R salt, after they were concentrated and separated coprecipitation with aluminium hydroxide. Zinc was concentrated and separated by ion exchange procedure, and cobalt by solvent extraction with dithizone, respectively. As the result of analysis of several sea-water samples, zinc was estimatezd at 0.3-0.5μg/1, while cobalt at 4-10μg/1.
In our previous report, the applicability of our proposed theory to the isobutane-normal butane-water system was verified by a series of experiments conducted on the propane-normal butane-water system and the propane-butene-1-water system. Under this theory, lower operational pressure is avaliable and no hydrate is formed, and thus it serves to find the composition of a more suitable refrigerant to be used for the desalination or the concentration of sea water.