Adsorptive Fractionation of Humic Acid at Air-Water Interfaces
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- 作者：Jun Ma ; Jin Jiang ; SuYan Pang ; Jin Guo
- 刊名：Environmental Science & Technology
- 出版年：2007
- 出版时间：July 15, 2007
- 年：2007
- 卷：41
- 期：14
- 页码：4959 - 4964
- 全文大小：157K
- 年卷期：v.41,no.14(July 15, 2007)
- ISSN：1520-5851
文摘
By using a simple bubble column, the adsorption behaviorof a commercial soil-humic acid (CHA) at air-waterinterfaces was investigated. At pH 4.0, the concentrationsof the CHA exhibited clear gradients in the bubblecolumn, and increased significantly along the columnheight; smaller concentration gradients were also observedat pH 6.0. These concentration profiles demonstrate thesurface activity of humic acid and pH-dependent affinitytoward air-water interfaces. Taking advantage of the bubblecolumn method, we interestingly found that the adsorptivefractionation of the CHA at air-water interfaces didoccur. The components with higher molecular weight andstronger UV absorptivity showed greater affinity toward air-water interfaces, despite that the fractionation pattern wasreduced to a certain extent as solution pH increased.The organic carbon-normalized pyrene partition coefficientKOC values deviated from the corresponding values oforiginal bulk solutions at both pH 4.0 and 6.0, and increasedalong the height of the column. Our results demonstratethe usefulness of the simple bubble column, and suggest thatthe adsorptive fractionation of humic acid at air-waterinterfaces might have implications for some naturalenvironments and engineered systems where air-waterinterfaces exist extensively.