The adsorption mechanism of lithium from simulated sea water on KW300 (2.5MgO·Al₂O₃·xH₂O) was investigated.The activation energy and enthalpy change of the lithium adsorption were evaluated to be 10.1kcal/mol and 8.45kcal/mol, respectively.The lithium uptake was found to vary with pH of the solution, exhibiting the maximum value at pH2≅8.The pH dependence was explained in terms of the cation-exchange reaction of Li⁺ with H⁺ of hydroxyl group on the surface of the adsorbent. However, since the enthalpy change for the lithium adsorption was considered to be larger than that of a simple ion-exchange reaction, these results suggested that the lithium adsorption was accompanied by certain complex reactions. The effect of other components coexisting in simulated sea water on the lithium uptake was studied, and as a result the lithium uptake was found to be decreased by magnesium ion and increased by sulfate ion

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In order to diminish the energy consumption for electrodialysis sea water desalination method, an electrodialyzer which structure and materials were optimized for sea water desalination and high temperature operation has been developed. And with the newly developed electrodialyzer, the performance for practical use of high temperature electrodialysis sea water desalination system using solar heat has been investigated.
A test plant with the capacity of 10m³/day was installed on Takami Island of Kagawa Prefecture. At this plant, a small energy consumption 8.54kW·h/m³ (DC power for electrodialysis) at 40°C was achieved. And through the long-run operation for about seven months from Feb. of 1983 to the present, the effectiveness and the reliability of the system were ascertained.

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Deposition of oil droplets at solid surfaces and removal of the deposited film by attrition of glass beads were studied to provide countermeasure toward fouling.
The droplets began to discretely deposit and gradually grow until the equilibrium state was made by repeating coagulation and separation, while the rate of deposition was considerably unstable in the initial stage.
The equilibrium amount of diposition was evidently dependent on the velocity of flow and the material of the surface.
In the experiment of removing foul, attrition rates of initially coated paraffin were measured by charging glass beads. The rate was linearly proportional to beads concentration and proportional in 2.5 power to the velocity of beads.

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The rate of uranium adsorption from sea water was measured for hydrous titanium oxide granules. These were prepared by urea-process crystallization and compression molding without using binder or other additive, but followed by crushing.
The maximum capacity of hydrous titanium oxide for adsorption of uranium from sea water was measured with milled powder prepared from the same crystalline substance, and found to be 315μg-U/g-Ti.
Analysis of the experimental results showed the velocity controlling step in the adsorption by the granular adsorbent to be the diffusion of uranium within the adsorbent granules. The internal diffusion coefficient was found to be 1.6×10^-6cm²/day, from the calculation utilizing the maximum adsorption capacity of 315μg-U/g-Ti.

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Measurement was carried out about the rates of uranium adsorption from sea water by various granular adsorbents prepared from hydrous titanium oxide by compression molding and crushing. The result indicated the existence of two different types of diffusion mechanism-one with the adsorption rate controlled by particle diffusion and the other with the rate controlled by film diffusion. The granules exhibiting the latter diffusion mechanism were found to be characterized structurally by bundles of fibrous crystals about 0.1μm in length.
The uranium adsorption capacities of hydrous titanium oxides, intermediates for the commercial production of titanium oxides, were observed to vary with crystal form, source of raw material, and manufacturing conditions. Also, the internal diffusion coefficients of these hydrous titanium oxides were found about 0.2×10^-6cm²/day, considerably lower than that of crystalline hydrous titanium oxide made by the urea method.

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[in Japanese]

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The results of the field survey were summarized as follows:
(1) Oceanography: The water in the offshore of Nauru Island was vertically divided into the following three layers by the analysis of T-S diagram.
a. Equatorial surface water; Less than 100m in depth, High temperature: 28.7°C, Low salinity: 34.1-34.6‰
b. Tropical water; Around 200m in depth, Temperature: 11.6-21.8°C, High salinity: 35.3‰.
c. Equatorial intermediate water; More than 500m in depth, Low temperature: less than 10.0°C, Low salinity: less than 35‰.
(2) Quality of water: Nutrients (phosphate, silicate, nitrate) were poor in the equatorial surface water (0-100m) in the offshore of Nauru Island due to phytoplankton's consumption.The concentration of these nutrients gradually increased in the layer deeper than 100 m.It was a typical vertical-distribution pattern in the tropical water.Other parameters related to productivity such as COD, turbidity, chlorophyll-a and cell number of phytoplankton, reached the maximum around 100 m in depth which indicated the maximum standing crop of phytoplankton in this layer.
(3) Plankton: At the sampling stations located in the offshore of the OTEC plant, phytoplankton showed a great variety in the composition of species without any particular dominant species. Diatoms, dinoflagellates, monods, and cocolithophorids were vertically most abundant in the 50-100m layer, which substantially coincided with the maximum of chlorophyll in the surface layer. Judging from the cell numbers of phytoplankton, the production of phytoplankton was considered high in the water around Nauru Island.Zooplankton consisted of protozoans (ciliates, radiolarians, foraminiferans), copepods, pteropods, oikopleurans and others. They were mainly distributed in the water shallower than 200m, but very few of them were found in the deeper layer.
4) Attaching organisms: Twenty-five species were identified from all the sampling stations. Most of them were the secondary attaching organisms such as periwinkies, rockshells, impets and other crawling organisms. There were found very few primary attaching organisms such as algae, barnacles, worm shells and other sessile organisms, which were known to be fouling organisms attaching to underwater facilities. No attaching organisms were observed on the inner surface of intake and outlet pipes except a chalk-tube worm and sea anemones which were considered to have attached after the suspension of the, operation.
(5) Intertidal organisms: The number of species by taxon was as shown below.
Corals Several species
Crabs and hermit crabs 23
Seashells 66
Sea urchins and sea cucumbers 10
Sea weeds (macrophyte) 6

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