Solubility and speciation of iron in cementitious systems
Solubility and speciation of iron in cementitious systems
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DOI：
10.1016/j.cemconres.2021.106620
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发表时间：
2021-10-06
影响因子：
11.4
通讯作者：
Angst, Ueli M.
中科院分区：
文献类型：
--
作者：
Furcas, Fabio E.;Lothenbach, Barbara;Angst, Ueli M.
水铁水解产物和氯络合物影响钢的腐蚀动力学，并决定腐蚀产物形成的数量和类型。在这里，我们编制了一个热力学数据库，专门用于水铁和固体氧化物以及氯配合物，旨在描述它们的形态和溶解度在胶凝系统感兴趣的主要化学环境中。我们比较热力学计算的经验数据，从胶凝系统的孔隙溶液的元素组成。发现水泥孔隙溶液中溶解的铁浓度与热力学预测有很大的不同。特别是，测量的铁（II）浓度可以超过热力学极限2-5个数量级。此外，实验获得的铁在氯化物存在下的溶解度超过热力学预测。我们讨论了这些差异可能是由迄今为止未知的铁配合物、中间相（如氯化物绿锈）的稳定或由于（动力学）沉淀的阻碍来解释的。
Aqueous iron hydrolysis products and chloride complexes influence steel corrosion kinetics and dictate the amount and type of corrosion products formed. Here, we compile a thermodynamic database devoted to aqueous iron species and solid oxides as well as chloride complexes, aiming to describe their speciation and solubility within the prevailing chemical environment of interest for cementitious systems. We compare thermodynamic calculations to empirical data on the elemental composition of pore solutions from cementitious systems. It is found that dissolved iron concentrations in cement pore solutions can differ considerably from thermodynamic predictions. In particular, measured Fe(II) concentrations can exceed the thermodynamic limit by 2-5 orders of magnitude. Additionally, experimentally obtained iron solubility in the presence of chloride exceed thermodynamic predictions. We discuss that these differences may be explained by so far unknown iron complexes, stabilisation of intermediate phases such as chloride green rust, or due to (kinetic) hindrance of precipitation.