Kinetics and Mechanisms of Pb(II) Sorption and Desorption at the Aluminum Oxide-Water Interface

详细信息    查看全文

• 作者：Daniel G. Strawn ; André ; M. Scheidegger ; and Donald L. Sparks
• 刊名：Environmental Science & Technology
• 出版年：1998
• 出版时间：September 1, 1998
• 年：1998
• 卷：32
• 期：17
• 页码：2596 - 2601
• 全文大小：126K
• 年卷期：v.32,no.17(September 1, 1998)
• ISSN：1520-5851

文摘

The fate of Pb in the environment is highly dependent onsorption and desorption reactions on solid surfaces. Inthis study Pb sorption and desorption kinetics on ges/gifchars/gamma.gif" BORDER=0 >-Al₂O₃at pH 6.50, I = 0.1 M, and [Pb]_initial = 2 mM were investigatedusing both macroscopic and spectroscopic measurements.X-ray absorption fine structure (XAFS) spectroscopyrevealed a Pb-Al bond distance of 3.40 Å, consistentwith an inner-sphere bidentate bonding mechanism. XAFSresults show no change with time in the average localatomic structure surrounding the Pb and no indication ofthe formation of Pb surface precipitates. Adsorption kineticswere initially fast, resulting in 76% of the total sorptionoccurring within 15 min, followed by a slow continuoussorption reaction likely resulting from diffusion throughmicropores. Desorption at I = 0.1 M and pH 6.50 was studiedusing a cation-exchange resin as a sink for Pb(aq).Under these conditions, Pb desorption was 98% reversiblewithin 3 days of incubation time. Furthermore, desorptionand adsorption kinetics demonstrated similar trends: afast reaction followed by a slow reaction. The useof spectroscopy combined with adsorption and desorptionkinetic studies has revealed important information onthe interaction between lead and aluminum (hydr)oxides.This information is valuable for predicting the fate of Pb inthe environment.