高浓度铝酸钠溶液结构

摘要

研究不同苛性比(1.47~4.44)、不同氧化钠浓度(50~382 g/L)的铝酸钠溶液紫外吸收光谱,对比发现高浓度铝酸钠溶液在320~340 nm处出现一个新的吸收峰,结合该处吸收峰随时间的变化特征,反演出320~340 nm处吸收峰对应的离子结构;利用量子化学计算铝酸钠溶液中可能存在的含铝离子或分子的紫外吸收峰以验证反演的离子结构.结果表明:随着氧化钠浓度和苛性比的增大以及时间的延长,铝酸钠溶液中聚合离子的数量以及聚合的复杂程度均呈上升趋势;320~340 nm处出现的新吸收峰为在高浓度溶液中出现的以—Al—(OH)2—Al—桥连的聚合离子,其中铝离子的配位数为4或者5.%By comparing the UV absorption spectra of sodium aluminate solutions with caustic ratio ranging from 1.47 to 4.44 and the sodium oxide concentration ranging from 50 to 382 g/L, it is found that a new absorption peak appears at 320-340 nm in the sodium aluminate solution with high concentration. According to the characteristic of the absorption peak with time, the corresponding ionic structure for the 320-340 nm absorption peak was speculated.The quantum chemical calculation of the UV absorption spectra for the corresponding aluminum ions or molecules was used to verify the speculations. The results show that the concentration of sodium oxide, caustic ratio and time can affect the characteristics of polymerization ions in sodium aluminate solution. The new absorption peak of 320-340 nm corresponds to the polymerization ions connecting with—Al—(OH)2—Al— bridge with coordination number of 4 or 5.