Fe3+纳米胶体颗粒的光吸收边蓝移与溶液中Al/Fe比的关系

合成了n（Al）／n（Fe）和碱化度不同的45个聚合氯化铝铁（PAFC）样品，进行了光谱分析，结果显示光吸收边蓝移或红移以及Fe（Ⅲ）羟基氧化物和Al-Fe共聚体纳米胶体颗粒大小分布与溶液的Al／Fe比和碱化度（B=[OH]／[Al＋Fe]）密切相关。电镜观察和电子衍射分析表明：Al（Ⅲ）的加入使Fe（Ⅲ）羟基氧化物和Al-Fe共聚体纳米胶体颗粒变小、有序度降低是造成PAFE光吸收边蓝移和保持胶体颗粒在亚稳定状态下存在的重要原因。当n（Al）／n（Fe）〉8：2后，PAFC溶液中Fe（Ⅲ）羟基氧化物和Al-Fe共聚体胶体主要以〈10m的纳米颗粒形态存在，对应的光谱能级提高到26000cm^-1以上，且各种曰值下Fe^3＋的光谱能级趋于一致。这表明，在大量Al（Ⅲ）存在条件下，PAFE中Fe3^＋的所处的化学环境相似。点能谱分析显示，n（Al）／n（Fe）=4：6的样品中颗粒物的化学计量比最接近AlOOH，FeOOH，溶液的稳定性最差。

RELATIONSHIP OF BLUE SHIFT OF Fe3+NANO-COLLOIDAL PAPRTICLES' ABSORPTION SPECTRA WITH Al/Fe MOLAR RATIO IN POLYALUMINUM FERRIC CHLORIDE SOLUTIONS

Blue and red shifts of the absorption edges of 45 samples of polyaluminum ferric chloride(PAFC) are closely related with nano-colloidal particle size alteration of Fe()hydroxyl polymer and Al-Fe co-aggregate and with Al/Fe molar ratio and basicities (B=[OH]/[Al+Fe]) in PAFC solutions. Observations under a high resolution transmitted electron microscope and electron diffraction analysis of crystal structure showed that the addition of Al() in PAFC is a dominant factor causing colloidal particle size to decrease and long-range disorder of ferric oxide hydroxyl polymer and Al-Fe co-aggregate and this is an important cause for the blue shift of absorption edges and the particles being kept in sub-stability state. In the case of Al/Fe molar ratio>82,the principal colloidal particles of Fe()oxide hydroxyl polymer and Al-Fe co-aggregate in PAFC solutions are <10 nm ,the energy scales of electron transition of Fe~(3+)in PAFC solutions are over 26000 cm~(-1) and tend to be unanimous at variable B ,which displays that the chemical surroundings of Fe~(3+) are the same as in PAFC solutions with the presence of larger quantities of Al()oxide hydroxyl polymer.Compositional analysis of nm-level area and microanalysis of element distribution using EDS showed that the stoichiometry of particles in Al/Fe molar ratio 46 PAFC solution is nearest those of AlOOH and FeOOH, so the stability of the solution is poor.