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The objective of this study is to evaluate the applicability of a seeded batch crystallization method as a pretreatment stage to the reduction of the the scaling potential of seawater. The crystallization process of calcium carbonate in supersaturated seawater is studied experimentally in a seeded batch crystallizer. Results show that the initial pH value of seawater must be adjusted to be in the range of 8-9. Calcite seeds will not have the potential to start the growth process in seawater at he the normal pH (7.36) compared to the above mentioned range. The growth kinetic parameters are determined from the measured desupersaturation curves. It is found that the growth process of calcite is controlled by surface integration step. The growth rate of calcite increases with increasing temperature and seeding ratio (up to 1 g/L), while it decreases with increasing the salinity of seawater. Crystals of calcite morphology are found to be growing faster than seeds of aragonite morphology. Stirrer speed has no distinct effect on the growth rate of calcite in seawater.

Fine particles of a hydrogen storage alloy (LaNi3.8Co0.5Mn0.4Al0.3) were microencapsulated with a thin film of nickel of about 0.6 μm thickness. The microencapsulated alloy powders were used as an anode material in a sealed nickel/metal hydride battery. The battery characteristics were compared with those of a battery with a bare (uncoated) alloy anode. The battery using the bare alloy was less stable compared to the coated alloy due to the role of the coated nickel as an oxygen barrier for protecting the alloy surface from oxidation. In addition, charge-discharge characteristics were improved greatly by the nickel coating, especially at high rates and at low temperatures due to the role of nickel as a microcurrent collector. So the microencapsulation of the alloy powders improves the performances of the alloy electrode.

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