Ionization equilibriums of silicic acid and polysilicate formation in aqueous sodium chloride solutions to 300.degree.C
Ionization equilibriums of silicic acid and polysilicate formation in aqueous sodium chloride solutions to 300.degree.C
复制标题
300°C 氯化钠水溶液中硅酸和聚硅酸盐形成的电离平衡
DOI：
--
复制
发表时间：
1977
期刊：
影响因子：
--
通讯作者：
R. Mesmer
中科院分区：
文献类型：
--
作者：
R. Busey;R. Mesmer
在氢电极浓缩池中，用精密电位滴定技术研究了硅酸和聚硅酸盐在碱性溶液中的电离行为。在温度60~290/sup 0/C，Si(IV)浓度0.005~0.05m的1mNaC l溶液中，研究了聚硅酸盐的形成。在最低的二氧化硅浓度下，在较宽的温度和pH范围内只有单核物种。当羟基数从0.7到1.0(每硅的平均电荷)时，在较高的Si(IV)浓度下会出现快速平衡的小聚硅酸盐。聚硅酸盐的生成量随着温度的升高而减少。在0.1~5.0mNaCl50和300/sup0/C范围内，精确测定了最重要反应的平衡商：Si(OH)/sub4/(Aq)+OH/sup-/断箭SiO(OH)/sub3//sup-/+H/sub2/O，在1mNaC中，50和300/sup 0/C时，反应平衡商的对数分别为3.96和2.20；在5mNaC中，相同温度下，该反应的平衡商分别为4.32和2.26。给出了一个可以计算反应热力学参数的解析表达式。盐浓度的微小影响被解释为很少或没有钠离子络合的证据。
The ionization behavior of silicic acid and polysilicate formation in basic solutions have been studied by precise potentiometry using titration techniques in a hydrogen-electrode concentration cell. Polysilicate formation was studied in 1 m NaCl solutions at temperatures from 60 to 290/sup 0/C and at Si(IV) concentrations 0.005 to 0.05 m. At the lowest silica concentration only mononuclear species occur over wide temperature and pH ranges. At hydroxyl numbers from about 0.7 to 1.0 (average charge per silicon) small polysilicates which equilibrate rapidly occur at higher Si(IV) concentrations. Polysilicate formation decreases with increasing temperature. The equilibrium quotient for the most significant reaction, Si(OH)/sub 4/(aq) + OH/sup -/ broken arrows SiO(OH)/sub 3//sup -/ + H/sub 2/O, has been precisely determined from 0.1 to 5.0 m NaCl and to about 300/sup 0/C. Values of the logarithm of the equilibrium quotient for the reaction are 3.96 and 2.20 at 50 and 300/sup 0/C in 1 m NaCl and 4.32 and 2.26 at the same two temperatures in 5 m NaCl. An analytical expression from which the thermodynamic quantities for the reaction can be computed is presented. The small effect of salt concentration is interpreted as evidence for little or no sodium ion complexing.