水解聚合铝阳离子Al_(13)和Al_(30)的^(27)Al核磁共振定量研究

Quantitative Studies on Keggin Polycation Al_(13) and Al_(30) in Hydrolytic Polymeric Aluminum Aqueous Solution by ^(27)Al Nuclear Magnetic Resonance

采用不同磁场强度的NMR谱仪和不同测试温度,对水解聚合铝溶液中Keggin结构的聚合铝阳离子形态的定量分析方法进行了研究。检测结果表明,高场27A l NMR分析技术不仅能精确定量地检测出水解聚合铝溶液中具有Keggin结构的[A lO4A l12(OH)24(H2O)12]7+(简称A l13)聚合阳离子,而且还能定量地检测出[(A lO4)2A l28(OH)56(H2O)26]18+(简称A l30)聚合阳离子。提高测试温度,有利于降低A l30共振峰的线宽,增强其分辨率。在70℃测试温度下,采用高场27A lNMR分别对8种中、高浓度(0.1~2.0 mol/L)水解聚合铝溶液中的A l13和A l30形态分布进行了定量研究,证实了A l30形态是高浓度水解聚合铝溶液中的一种优势聚合形态。

A quantitative analytical method of Keggin polycation[AlO4Al12（OH）24（H2O）12]^7＋, （ Al13 ） and [（AlO4）2Al28（OH）56（H2））26]^18＋,（ A30 ） in hydrolytic polymeric aluminum （HPA） aqueous solution was developed, and the species distribution of eight HPAs with total aluminum concentrations （AlT） between 0.1 and 2.0 mol/L were studied quantitatively using high field 27Al nuclear magnetic resonance （NMR） under 70℃. The concentrations of Al3 and Al30 can be measured accurately by this method. The linewidth of Al30 are very sensitive to temperature and become narrower on heating or measured on high field NMR spectrometer, and the resolution will be improved. AlT is a dominant factor of influencing the aluminum species distribution in high concentrated HPA（AlT≥0.5 mol/L）. The concentration of Al13 increases with the increasing of AlT while AlT G0.5 mol/L, and decreases with the increasing of AlT while AlT≥0.5 mol/L. The concentration of Al30 increases with the increasing of AlT, and it is greater than the concentration of Al13 while AlT 〉 0. 5 mol/L. Al30 becomes one of dominant polymeric aluminum species while the AlT 90. 5 mol/L.