Most of ion-exchange membranes are formed by polymerization of styrene and divinylbenzene and then the ion-exchange groups are introduced into the membranes. During the polymerization process, the phaseseparation takes place and it is considered that the formed morphology affects the performance of membrane remarkably. Usually rubber component is added to the mixture of styrene and divinylbenzene in order to improve the brittleness of the membrane and this may induce the phase separation. In this study, the structure development during polymerization of styrene and divinylbenzene in the existence of rubber was measured by a light scattering, an optical microscope and a transmission electron microscope. A peak in the light scattering profile appeared and regularly phase-separated morphology was observed by optical microscopy. These results mean that the phase-separation into polystyrene-rich phase and rubber-rich phase took place via spinodal decomposition mechanism (polymerization induced phase separation). It was also suggested that the phaseseparated morphology can be controlled by changes of polymerization speed and miscibility between polystyrene and rubber. The phase-separated morphology of membrane polymerized in the existence of foundation cloth which consisted of poly (vinyl chloride) was also observed. It was found that the domain size of phase-separated morphology was remarkably different between inside and outside of foundation cloth.

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A simplified model is developed in order to analyze multiple-effect distillation process of sea water, and the feasibility of concentration with the high performance required for salt manufacture is investigated. The performance ratio, which is defined as the ratio of the total distillate rate to the feed steam rate, required for the concentration with the same energy as that consumed in a current electrodialysis and multi-effect distillation combined system is estimated to be approximately 14, from the mass and energy balances of the system. This ratio is shown to be feasible from the analysis based on the model. Thorough heat recovery from distillate and vapor generated due to flash evaporation during the effects is suggested to be indispensable for the attainment of the required performance.

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A numerical simulation is performed for seawater concentration by thermal evaporation using a multiple effect evaporator in order to investigate its economical feasibility. Amount of required energy is compared with that for the seawater concentration by electrodialysis. The system considered is a series of falling film-long tube vertical evaporators. In the calculations, dependences of various properties on temperature and concentration are considered. In addition to the influences of operating conditions on the process, the effectiveness of waste heat recovery is investigated. The simulation demonstrated that the thermal evaporation under a realistic and reasonable condition requires about 8 times as much energy as the electrodialysis. However, it is also suggested that the thermal evaporation can be comparable when the seawater is concentrated up to 26% and the last two or three stages are used for crystallization.

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This work is composed of part-1 and part-2. Part-1 was reported in Bull. Soc. Sea Water Sci. Jpn., 57,(2), pp.93-102 (2003). This manuscript is part-2 and intended for the conditions which participate in corrosion velocity. Some figures and tables are quoted from excellent corrosion textbooks shown at“References”. I wish to express my gratitude to the authors and the publishers.

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The author is deeply grateful for the academic prize awarded from the society of sea water science, Japan. This report is the summary of plenary lecture presented for the prize.
During investigation of some hydroxyapatites [Ca₁₀(PO₄)₆(OH)₂: HAp -Ca₁₀(PO₄)_4.2(SiO₄)_1.7(OH)₆: SiAp], the author discovered that“Lattice Ca²⁺ions” of the apatites were selectively ion-exchanged for such notorius cations as Pb²⁺or Cd²⁺ions in aqueous solution at room temperature and such interesting ion-exchangers were named as“Lattice Ion Ion-exchanger” by the author. Thus, to selectively separate and uptake small amounts of K⁺ions from seawater in the presence of a large amount of Na⁺ions, K⁺ion memorizing lattice ion ionexchangers have been investigated and Na⁺form taeniolite (Na⁺Mg₂LiSi₄O₁₀·2H₂O: Na⁺T) was found to be a promising inorganic ion-exchanger. Lattice Na⁺ions of the Na⁺T were highly selectively ion-exchanged for K⁺ions in dehydrated state from seawater. Further, SiAp and its extented inorganic ion-exchangers such as hydrotalcite and calcium hydroxide were found to have disinfection effect for Ecoli cells in wastewater. The author hopes that the above inorganic ion-exchangers will be extended to be key materials in environmental and water 21st century.

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The concentrations of chlorophyll a (Chl a), adenosine triphosphate (ATP) and bacterial cell numbers in picosized fractions (0.2-0.7μm) were measured in the euphotic zone from subtropical regions to subarctic regions of the central and eastern North Pacific Ocean, in order to evaluate the biogeochemical significance of ATP for estimating bacterial carbon biomass. The ATP concentration varied remarkably depending on depths, latitudes or longitudes, whereas the Chl a concentration was found to be nearly constant. The statistical analyses suggest that the ATP concentration significantly correlated to seawater temperature, whereas there are no correlations between ATP concentration and Chl a concentrations and bacterial numbers. These results imply that the regional variation of ATP concentration was mainly influenced by not only the biomass of living heterotrophic bacteria, but also the physiological condition (active or inactive condition) itself accompanied by the variation in seawater temperature.

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