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在广泛pH范围内研究了硅酸聚合中盐效应的机理。实验结果表明:外加盐的阳离子既可与水配位形成水合金属阳离子,又可与硅酸负离子形成配合物。因此外加盐的阳离子同时以静电效应和化学反应两种机理来影响硅酸的聚合速度,这种影响随溶液pH增大而加强。在强酸性溶液中,外加盐被酸化成的酸和硅酸或硅酸阳离子反应,以化学反应机理来改变硅酸的聚合速度。这一作用随溶液pH增大而减小。根据上述机理,提出了一个表示硅酸聚合速度与包括盐效应在内的各种因素的关系式,由此求得的计算值与实验值基本符合。
The mechanism of salt effect in silicic acid polymerization has been studied in a wide range of pH. The experimental results show that the cation added salt can form hydrated metal cations with water and form complexes with negative ions of silicic acid. Therefore, the addition of salt cations affect the polymerization rate of silicic acid by both the electrostatic and chemical reactions at the same time. This effect is enhanced with increasing pH of the solution. In strongly acidic solutions, the acid to which the additional salt is acidified reacts with silicic acid or silicate cations to modify the rate of polymerization of silicic acid by a chemical reaction mechanism. This effect decreases with increasing pH of the solution. According to the above mechanism, a relationship between the polymerization rate of silicic acid and various factors including salt effect is proposed, and the calculated value is in good agreement with the experimental value.