Mechanistic studies of silica polymerization from supersaturated aqueous solutions by means of time-resolved light scattering.
Mechanistic studies of silica polymerization from supersaturated aqueous solutions by means of time-resolved light scattering.
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通过时间分辨光散射研究过饱和水溶液中二氧化硅的聚合机理
DOI：
10.1021/la502730y
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Kempter
中科院分区：
文献类型：
--
作者：
Kempter
过饱和硅酸钠水溶液中的二氧化硅聚合是一种基本的矿化过程，与技术应用和生物过程具有广泛的相关性。为了有助于更好地理解硅酸钠在环境条件下聚合的机理，首次以时间分辨方式对颗粒质量和尺寸的演变进行了多角度静态和动态光散射联合研究。光散射实验通过硅钼酸盐方法对单体硅酸盐浓度衰减的时间分辨分析进行补充。在 pH 值 7 和 8 的不同硅酸盐浓度下研究了颗粒的形成。联合实验揭示了单体的损失，这与通过单体添加过程生长的致密球形颗粒的形成是平行的。硅酸盐含量增加到 750 ppm 增加了成核程度，同时减少了反应开始和颗粒实际开始生长之间观察到的滞后时间。一旦二氧化硅含量远大于 1000 ppm，颗粒的形成就会通过颗粒-颗粒附聚而成功，从而形成更大的分形颗粒。当光散射导致团聚变得明显时，单体浓度已经达到其平衡值。 pH 值增加至 8 再次表明通过单体添加过程形成颗粒。然而，即使初始二氧化硅含量为 2000 ppm，成核程度也会增加，颗粒间的团聚也会受到抑制。
Silica polymerization in a supersaturated aqueous solution of sodium silicate is a fundamental mineralization process with broad relevance for technical applications as well as for biological processes. To contribute to a better understanding of the mechanism underlying the polymerization of sodium silicate under ambient conditions, a combined multiangle static and dynamic light scattering study on the evolution of particle mass and size is applied for the first time in a time-resolving manner. The light scattering experiments are complemented by a time-resolved analysis of the decay of the concentration of monomeric silicate by means of the silicomolybdate method. Particle formation was investigated at a variable concentration of silicate at pH 7 and 8. The joint experiments revealed a loss of monomers, which is parallel to the formation of compact, spherical particles growing by a monomer-addition process. An increase in the silicate content of up to 750 ppm increased the extent of nucleation and at the same time decreased the lag time observed between the start of the reaction and the actual onset of the growth of particles. Once the silica content is considerably larger than 1000 ppm, the formation of particles is succeeded by particle–particle agglomeration leading to larger fractal-like particles. By the time agglomeration becomes noticeable with light scattering, the monomer concentration has already reached its equilibrium value. An increase in the pH to 8 again revealed particle formation via a monomer-addition process. However, the extent of nucleation was increased and particle–particle agglomeration was inhibited even at an initial silica content of 2000 ppm.
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DOI：
10.1021/jp403985m
发表时间：
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期刊：
The journal of physical chemistry. B
影响因子：
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