水溶液体系铝硅酸钠微结构的拉曼光谱和量子化学从头计算研究

Raman Spectra and Quantum Chemistry ab initio Calculation Study on Microstructure of Sodium Aluminosilicate Aqueous Solutions

选取了代表性水溶液体系铝硅酸钠的典型试样:铝酸钠溶液、硅酸钠溶液、铝硅酸钠溶液,分别测定了它们的拉曼光谱。构建了系列铝硅酸钠溶液微结构模型,应用量子化学从头计算方法优化了空间几何构型,并计算了其拉曼光谱,计算结果分别与相应试样的实验拉曼光谱进行对比。结果表明:在高浓度条件下,铝酸钠溶液中铝物种的主要存在形式是Al(OH)-4(Q0)和Al2O(OH)2-6(2Q1),低浓度时只存在Q0结构的铝酸根离子,以4Q0聚集态的四水合分子形式存在;在2.0M Na2SiO3溶液中,硅酸钠团簇结构可能的存在形式是四水合Na2H2SiO4;在铝硅酸钠溶液中,铝硅酸根离子的形态是由Si-O-Si和Al-O-Si键以不同铝硅原子配比相互连接形成的环状或链状结构。

Three kinds of typical samples of sodium aluminosilicate aqueous solutions including sodium aluminate,sodium silicate and sodium aluminosilicate solutions were investigated by Raman scattering spectroscopy respectively.Quantum chemistry ab initio calculation was applied to optimize geometric structure and calculate Raman spectra of a series of solution model cluster structural units.Calculated and experimental Raman spectra were compared with each other.The results show the dominant aluminate ions exist in the form of Al（OH）4^-（Q0）and Al2O（ OH） 6^2-（2Q1）in high concentration sodium aluminate solution while the fundamental structural unit which may be present under dilute condition is 4Q0 with four H2 O molecules of hydration.In 2.0M Na2SiO3 solution,it appears that Na2H2SiO4 monomer with at most four H2 O molecules of hydration is the most probable form of sodium silicate clusters.The structure of aluminosilicate species in sodium aluminosilicate solutions would appear to be ring or chain structure combined by Si-O-Si and Al-O-Si bond with different Al/Si atomic ratio.