The Nature of Polynuclear Oh-Al Complexes in Laboratory-Hydrolyzed and Commercial Hydroxyaluminum Solutions
The Nature of Polynuclear Oh-Al Complexes in Laboratory-Hydrolyzed and Commercial Hydroxyaluminum Solutions
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DOI：
10.1346/ccmn.1994.0420313
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发表时间：
1994-06
影响因子：
2.2
通讯作者：
Wei-Zi Wang;P. Hsu
中科院分区：
文献类型：
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作者：
Wei-Zi Wang;P. Hsu
用Al-Ferron显色动力学、H+结构羟基中和动力学、27A1核磁共振波谱和硫酸盐沉淀等方法对实验室水解液和工业用氢氧化铝溶液进行了表征。结果表明，具有Keggin结构的Al13络合物仅在新鲜的、实验室水解的OH-A1溶液中占主导地位，其摩尔比为1.8或以上。这些物种逐渐转化为与Ferron反应缓慢的其他多核形式，27A1核磁共振谱不能检测到这些形式，并在Na2SO4添加后生成不同的碱性硫酸铝。这些更稳定的络合物可以最好地解释为具有Al(OH)3-碎片结构。在所研究的三种商品氯化铝(ACH)溶液中，Al13络合物只占总铝的一小部分。超过80%的铝以核磁共振光谱无法检测到的形式存在，类似于陈年的实验室水解的OH-Al溶液中的慢反应络合物。一小部分慢反应的络合物似乎是亚微米颗粒，充当三水铝石形成的核心，或者是Al13络合物的聚集体，在稀释后分散到Al13中。聚合氯化铝(PA)溶液类似于实验室中陈化的OH-Al溶液。
Laboratory-hydrolyzed and commercial OH-Al solutions were characterized using kinetics of Al-ferron color development, kinetics of structural OH neutralization with H+, 27A1 NMR spectroscopy, and sulfate precipitation. The results showed that the Al13 complexes having the Keggin structure were dominant only in fresh, laboratory-hydrolyzed OH-A1 solutions of OH/A1 molar ratio = 1.8 and above. These species gradually converted to other polynuclear forms that reacted with ferron slowly, were not detectable by 27A1 NMR spectroscopy, and yielded different basic Al sulfates following Na2SO4 addition. These more stable complexes can best be interpreted to have a Al(OH)3-fragment structure. In the three commercial aluminum chlorohydrate (ACH) solutions studied, Al13 complexes accounted for a small portion of the total Al present. More than 80% of the Al was present as species that were not detectable with NMR spectroscopy and resembled the slow-reacting complexes in aged, laboratory-hydrolyzed OH-Al solutions. Small portions of the slow-reacting complexes appeared to be submicron particulates that acted as nuclei for gibbsite formation or aggregates of Al13 complexes that dispersed to Al13 upon dilution. Polyaluminum chloride (PA) solution resembled the moderately aged laboratory-hydrolyzed OH-Al solutions.