IDENTIFICATION AND QUANTIFICATION OF THE AL13 TRIDECAMERIC POLYCATION USING FERRON
IDENTIFICATION AND QUANTIFICATION OF THE AL13 TRIDECAMERIC POLYCATION USING FERRON
复制标题
DOI：
10.1021/es00029a006
复制
发表时间：
1992-05-01
影响因子：
11.4
通讯作者：
BERTSCH, PM
中科院分区：
文献类型：
--
作者：
PARKER, DR;BERTSCH, PM
历史上，需要 Al-27-NMR 光谱来明确鉴定 AlO4Al12(OH)24(H2O)12(7+) 聚阳离子（“Al13”），但最近的研究表明，它可能等同于与分光光度铁离子试剂 (Alb) 表现出中等反应速率的多核 Al 部分。我们的目标是进一步测试这种对应关系并严格评估铁离子-Al13 反应动力学。部分中和的溶液以[Al]T=10(-4)-10(-2)mol·L-1、水解比为0.8-2.4、碱注入速率为0.2-20mL·h-1来制备。使用 Ferron 和 Al-27 NMR 对这些溶液进行定量分析，结果证实使用 Ferron 测量的 Alb 分数对应于新制备的溶液中的 Al13。铁离子-Al(b) 反应 (k(b)) 的表观伪一级速率系数取决于反应混合物中的总铁离子浓度。对本工作和之前一些研究中拟合的 k(b) 值的检查表明，如果正确评估，它们确实是一致且可预测的，可以近乎确定地识别 Al13。因此，铁离子方法为 Al-27-NMR 分析提供了一种简单且廉价的替代方案，并允许在比目前 NMR 分析浓度低 10-100 倍的浓度（与天然水相关的浓度范围）下定量 Al13。
Historically, Al-27-NMR spectroscopy has been required for definitive identification of the AlO4Al12(OH)24(H2O)12(7+) polycation ("Al13"), but recent studies suggest that it might be equatable to the polynuclear Al fraction that exhibits a moderate reaction rate with the spectrophotometric ferron reagent (Alb). Our objectives were to further test this correspondence and to critically evaluate the ferron-Al13 reaction kinetics. Partially neutralized solutions were prepared with [Al]T = l0(-4)-10(-2) mol L-1, hydrolysis ratios of 0.8-2.4, and base injection rates of 0.2-20 mL h-1. These solutions were quantitatively analyzed using ferron and Al-27 NMR, and the results confirmed that the Alb fraction measured with ferron corresponds to Al13 in freshly prepared solutions. The apparent pseudo-first-order rate coefficient for the ferron-Al(b) reaction (k(b)) is dependent on the total ferron concentration in the reaction mixture. Examination of fitted k(b) values from this work and from some previous studies revealed that they are, if properly evaluated, indeed consistent and predictable, permitting near-certain identification of Al13. The ferron method thus offers a simple and inexpensive alternative to Al-27-NMR analyses and allows quantification of Al13 at concentrations 10-100-fold lower than presently analyzable by NMR, a concentration range pertinent to natural waters.