Kinetics of phosphate adsorption on goethite: Comparing batch adsorption and ATR-IR measurements
Kinetics of phosphate adsorption on goethite: Comparing batch adsorption and ATR-IR measurements
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DOI：
10.1016/j.jcis.2006.04.015
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发表时间：
2006-08-15
影响因子：
9.9
通讯作者：
Avena, Marcelo
中科院分区：
文献类型：
--
作者：
Luengo, Carina;Brigante, Maximiliano;Avena, Marcelo
通过批量吸附实验和原位ATR-IR光谱研究了不同pH值、不同初始磷浓度和不同搅拌速度下针铁矿对磷酸盐的吸附动力学。批量吸附结果与几位作者报道的结果非常相似，并显示出在几分钟内发生相当快的初始吸附，随后在几天或几周内发生较慢的过程。结合ATR-IR实验中获得的磷酸盐信号，也可以监测吸附动力学，两种技术之间有很好的一致性。在pH为4.5时，形成了两种表面络合物：双齿非质子化(FeO)(2)PO2和双齿质子化(FeO)2(OH)PO络合物。随着反应的进行，这些物种的相对浓度有很小的变化，而且它们似乎是随着时间的推移而独立进化的。在pH为7.5和9时，表面的主要物种为(FeO)2PO2，在低浓度时还伴随有一种未知物种。它们似乎也随着反应的进行而独立进化。结果与快速吸附后缓慢扩散到孔内的机理一致，而与表面磷酸铁析出的机理不一致。(C)2006 Elsevier Inc.保留所有权利。
The adsorption kinetics of phosphate on goethite has been studied by batch adsorption experiments and by in situ ATR-IR spectroscopy at different pH, initial phosphate concentrations and stirring rates. Batch adsorption results are very similar to those reported by several authors, and show a rather fast initial adsorption taking place in a few minutes followed by a slower process taking place in days or weeks. The adsorption kinetics could be also monitored by integrating the phosphate signals obtained in ATR-IR experiments, and a very good agreement between both techniques was found. At pH 4.5 two surface complexes, the bidentate nonprotonated (FeO)(2)PO2 and the bidentate protonated (FeO)2(OH)PO complexes, are formed at the surface. There are small changes in the relative concentrations of these species as the reaction proceeds, and they seem to evolve in time rather independently. At pH 7.5 and 9 the dominating surface species is (FeO)2PO2, which is accompanied by an extra unidentified species at low concentration. They also seem to evolve independently as the reaction proceeds. The results are consistent with a mechanism that involve a fast adsorption followed by a slow diffusion into pores, and are not consistent with surface precipitation of iron phosphate. (c) 2006 Elsevier Inc. All rights reserved.