Abstract：
Sodium silicate solutions, also known as waterglass, have been found to have remarkable utility in a variety of applications. The cumulative weight of evidence from 70 years of varied analysis indicates that silicate solutions consist of a wide range of species, from monomers through oligomers, up to colloids. Moreover, the structure and distribution of these species are greatly dependent upon many parameters, such as solute concentrations, silica to alkali ratio, pH, and temperature. The most interesting and characteristic property of silicate solutions is their ability to form silica gels. Overall, despite extensive research using different spectroscopic and scattering techniques, many questions related to sodium silicate\'s dynamic structure, stability, polymerization, and gelation remain difficult to answer. The multitude of simultaneous reactions which restructure the silicate species at the atomic scale in response to variation in solution and environmental parameters, makes it difficult to investigate the individual events using only experimental data. Molecular modelling provides an alternative way to study the unknown areas in the aqueous silicate and silica gel systems, generating key insights into the chemical reactions at microscopic length scales. However, sufficient sampling remains a challenge for the practical use of molecular simulation for these systems. Based on both experimental and modelling studies, this review provides a detailed discussion over the structure and speciation of sodium silicate solutions, their gelation mechanism and kinetics, and the syneresis phenomenon. The goal is not only to review the current level of understanding of sodium silicate solutions, silica gels and characterization techniques suitable for studying them, but also to identify the gaps in the literature and open up opportunities for advancing knowledge about these complex systems. We believe that the future direction of research should be toward correlating atomistic, molecular, and meso-scale level details of interactions and reactions in silicate solution and establishing a fundamental understanding of its gelation mechanism and kinetics. We believe that this knowledge could eliminate the \"trial and error\" approach in manufacturing, and improve structural control in the synthesis of important materials derived from these solutions, such as silica gels and zeolites.
摘要：
硅酸钠溶液,也被称为水玻璃，已经发现在各种应用中具有显著的实用性。从70年的不同分析中得出的证据的累积权重表明，硅酸盐溶液由多种物种组成，从单体到低聚物，直到胶体。此外，这些物种的结构和分布在很大程度上取决于许多参数，如溶质浓度，二氧化硅与碱的比例，pH值,和温度。硅酸盐溶液最有趣和最典型的性质是它们形成硅胶的能力。总的来说,尽管使用不同的光谱和散射技术进行了广泛的研究，许多与硅酸钠动态结构有关的问题，稳定性,聚合，凝胶化仍然很难回答。许多同时发生的反应在原子尺度上重构硅酸盐物种，以响应溶液和环境参数的变化，这使得仅使用实验数据很难调查单个事件。分子建模提供了一种研究水性硅酸盐和硅胶系统中未知区域的替代方法。在微观尺度上产生对化学反应的关键见解。然而,足够的采样对于这些系统的分子模拟的实际使用仍然是一个挑战。基于实验和建模研究，这篇综述对硅酸钠溶液的结构和形态进行了详细的讨论，它们的凝胶化机理和动力学，和脱水收缩现象。目标不仅是回顾目前对硅酸钠溶液的理解水平，适合研究它们的硅胶和表征技术，而且还要找出文献中的差距，并为推进有关这些复杂系统的知识开辟机会。我们认为，未来的研究方向应该是相关原子，分子，以及硅酸盐溶液中相互作用和反应的细观尺度级别细节，并建立对其凝胶化机理和动力学的基本理解。我们相信这些知识可以消除制造业中的“反复试验”方法，并改善从这些溶液中合成重要材料的结构控制，如硅胶和沸石。
