Silica in aqueous environments
Silica in aqueous environments
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DOI：
10.1016/0022-3093(95)00562-5
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发表时间：
1996-03
影响因子：
3.5
通讯作者：
S. Sjöberg
中科院分区：
文献类型：
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作者：
S. Sjöberg
二氧化硅（SiO2）的水化学由许多耦合过程调节，例如溶解/沉淀、与水相中的阳离子和阴离子络合以及与颗粒-水界面处的阳离子和阴离子络合。此外，生物群的吸收在水圈的某些部分也很重要。二氧化硅的溶解强烈依赖于pH值，因为在pH值≤ 9时会形成硅酸（Si（OH）4）。在碱性更强的溶液中，形成单硅酸盐（SiO（OH）3−）、SiO2（OH）22−）和聚硅酸盐。这些聚硅酸盐的组成和热力学稳定性仍然没有完全了解。多年来，二氧化硅的表面化学已被广泛研究。基于最近的表面络合模型，热力学数据描述的酸/碱的性质，以及阳离子（金属离子）和阴离子的吸附/脱附反应已提交。二氧化硅表面的酸性性质已通过表面SiOH基团的酸度常数描述，pKa（intr.）= 6.8。此外，已经公布了几种金属离子的表面络合常数，显示出金属离子在水溶液中和在SiO2-水界面处的水解性质之间的强相关性。
The aqueous chemistry of silica (SiO2) is regulated by a number of coupled processes such as dissolution/precipitation, complexation to cations and anions in the aqueous phase and complexation to cations and anions at the particle-water interface. Further, uptake by biota is significant in parts of the hydrosphere. The dissolution of silica is strongly pH-dependent in that silicic acid (Si(OH)4) is formed at pH values ≤ 9. In more alkaline solutions, monosilicates (SiO(OH)3−), SiO2(OH)22−) and polysilicates are formed. Composition and thermodynamic stability of these polysilicates are still not fully understood. The surface chemistry of silica has been extensively studied throughout the years. Based on recent surface complexation models, thermodynamic data describing acid/base properties, as well as cation (metal ion) and anion adsorption/desorption reactions have been presented. The acidic properties of a silica surface have been described by an acidity constant for surface SiOH groups with pKa(intr.) = 6.8. Further, surface complexation constants for several metal ions have been published showing a strong correlation between hydrolytic properties of the metal ion in aqueous solution and at the SiO2-water interface.