Abstract: Precipitation of calcium and magnesium from seawater using CO2，the seawater of pH value in 8，the effects of the temperature and salinity were investigated in this research. When the salinity of seawater was 35‰，the removal rate of calcium increased from 90% to 95% when the temperature from 30 ℃ to 50 ℃. Meanwhile，the removal rate of magnesium was increased from 0 to 42%; the removal rate of calcium and magnesium also increased with the increasing temperature. When the temperature of seawater was 30 ℃，removal rate of calcium increased from 90% to 97% when salinity increased from 35‰ to 105‰. The removal rate of magnesium increased from 0 to 67%, the removal rate of calcium and magnesium increased with the increasing salinity as well. Solids precipitation was characterized using X-ray diffraction (XRD) analysis. The composition of precipitated solids varied with the changes in temperature and salinity. The optimum conditions of calcium removal from seawater under the experimental conditions in this paper were：temperature 30 ℃ and salinity 35‰.

Key words: carbon dioxide, removal rate of calcium, removal rate of magnesium, temperature of seawater, salinity of seawater

摘要： 对CO2法脱除海水中钙离子和镁离子进行研究，控制海水的pH值恒为8，考察温度、盐度对脱钙率和脱镁率的影响。结果表明，盐度35‰的海水，30～50 ℃时脱钙率由90%增长至95%，与此同时脱镁率由0增长至42%；脱钙率、脱镁率随温度升高而升高。在温度为30 ℃时，盐度35‰～105‰的海水脱钙率可由90%增长到97%，与此同时脱镁率由0增长到67%；脱钙率、脱镁率随盐度升高而升高。将得到的固体进行XRD检测可知，产物固相组成随温度、盐度的变化而变化。由此可知，海水盐度为35‰、pH值为8、温度为30 ℃是CO2法高效脱钙的最佳工艺条件。

关键词: 二氧化碳, 脱钙率, 脱镁率, 海水温度, 海水盐度