| Abstract |
| Calcium is one of the essential mineral elements in oceanic, fresh, and even drinking water. This study represented the changing patterns of the stable region of calcium ion in an aqueous system using pH-potential diagrams over temperature ranged from 15℃ to 105℃. Calcium species are categorized into two groups under the exclusion of the effects of other ions from the calcium-water system: Ca-Ca2+-Ca(OH)2 and CaH2-Ca2+-Ca(OH)2 system. In both systems, it indicated that while the region of calcium hydroxide predominantly expands as temperature rises, the stable regions of Ca(s) and CaH2(s) shrink. On the whole, there was a decline in the stable region of calcium ion at high temperature in terms of the absolute value of potential changed. Along with this results, carbonate system would be considered to understand substantial behaviour of calcium ion in natural water, interconnecting with the effects from atmospheric CO2, biological activities of calcareous marine organisms, and carbonate-solid system. |
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| Key Words |
| calcium, carbonate system, Eh-pH diagram, temperature, CO2, pH |
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