CO_2对砷酸钙稳定性影响的热力学分析

Thermodynamic Analysis of the CO_2 Effects on the Stability of Calcium Arsenates

通过沉淀和溶解两方面的实验数据,应用PHREEQC程序模拟了砷酸钙在不同CO2分压条件下溶解度的变化情况,发现环境中的CO2可使砷酸钙盐在酸度较高(pH大于8.3)的条件下发生不一致溶解,使其溶解度升高;CO2分压越大,砷酸钙盐发生不一致溶解的酸度越低;CO2主要影响3∶2和5∶3的砷酸钙盐,而对4∶2砷酸钙盐的影响较小。这对不同类型砷酸钙盐废物的处置是否应考虑CO2的因素提供了依据。

Solubility and stability of calcium arsenates under different CO2 pressures are studied based on the data of precipitation and solution experiments simulated by PHREEQC program. The result shows that calcium arsenates can dissolve incongruently by the effect of CO2 in high pH（pH〉8. 3）and make their solubility higher. The higher the CO2 pressure is, the lower the acidity of the incongruent dissolution is. The effects of CO2 mainly occur on the 3 ： 2 and 5 ：3 calcium arsenates, and less on the 4 ：2 calcium arsenate. These conclusions can give some suggestions whether the CO2 effects should be considered in calcium arsenates wastes disposal.