水体中25℃时Fe-H_2O体系溶解组分优势区域图和Pourbaix图

Predominance diagram of dissolved species and Pourbaix diagram of Fe-H_2O system in water at 25 ℃

对25℃不同总铁浓度时Fe-H2O体系可能存在的组分进行了热力学分析,计算了各溶解组分的浓度,运用浓度比较法为判据,确定液相和液相、液相和固相以及各固相之间的分界线,绘制了水体中不同浓度时Fe-H2O体系溶解组分优势区域图和Pourbaix图.对比不同浓度优势区域图时发现,在一定温度和压力下,总铁浓度的大小对Fe3+,Fe(OH)2+,HFeO2和FeO-2的优势区域影响不大,但对Fe2+,HFeO-2,Fe(OH)+的优势区域影响明显.随着总铁浓度的减小和碱化程度的逐步加强,Fe(OH)2和Fe3O4会发生一系列复杂的质子化和聚合作用.总铁浓度越高,多核组分Fe(s),Fe3O4(s),Fe(OH)2(s)和FeOOH(s)的稳定区域越大,性质越稳定.

The predominance diagram of dissolved species and a Pourbaix diagram of the Fe‐H2 O system in water are studied at 25 ℃ by a concentration comparison method . The concentration of dissolved species , borderlines for liquid phases or solid phases and borderlines between the solid and solid phase are calculated on the basis of thermodynamic analysis and electrochemical analysis with a total Fe concentration of CT（Fe）=1.0 × 10-4 mol-L -1 and CT（Fe）=1.0 × 10-7 mol-L -1 . The predominance diagram of dissolved species and the Pourbaix diagram of the Fe‐H2 O system are then plotted . Comparisons between predominance diagrams for different iron concentration show that at a specific temperature and pressure the total concentration of iron has little effect on the stable predominance regions of Fe3＋ , Fe（OH）2＋ , HFeO2 and FeO2- .However ,these conditions have a remarkable effect on Fe2＋ ,HFeO2-and Fe（OH）＋ .A series of hydroxylation and polymerization reactions may occur with Fe （OH ）2 and Fe3 O4 resulting in change the total concentration of iron and acidity . A higher total concentration of iron results in a more big area and＆nbsp;stable for the species Fe（s） ,Fe3O4（s） ,Fe（OH）2（s）and FeOOH（s） .