Kinetics of Desorption of Organic Compounds from Dissolved Organic Matter

详细信息    查看全文

• 作者：Frank-Dieter Kopinke ; Ksenia Ramus ; Juergen Poerschmann ; Anett Georgi
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：December 1, 2011
• 年：2011
• 卷：45
• 期：23
• 页码：10013-10019
• 全文大小：863K
• 年卷期：v.45,no.23(December 1, 2011)
• ISSN：1520-5851

文摘

This study presents a new experimental technique for measuring rates of desorption of organic compounds from dissolved organic matter (DOM) such as humic substances. The method is based on a fast solid-phase extraction of the freely dissolved fraction of a solute when the solution is flushed through a polymer-coated capillary. The extraction interferes with the solute鈥揇OM sorption equilibrium and drives the desorption process. Solutes which remain sorbed to DOM pass through the extraction capillary and can be analyzed afterward. This technique allows a time resolution for the desorption kinetics from subseconds up to minutes. It is applicable to the study of interaction kinetics between a wide variety of hydrophobic solutes and polyelectrolytes. Due to its simplicity it is accessible for many environmental laboratories. The time-resolved in-tube solid-phase microextraction (TR-IT-SPME) was applied to two humic acids and a surfactant as sorbents together with pyrene, phenanthrene and 1,2-dimethylcyclohexane as solutes. The results give evidence for a two-phase desorption kinetics: a fast desorption step with a half-life of less than 1 s and a slow desorption step with a half-life of more than 1 min. For aliphatic solutes, the fast-desorbing fraction largely dominates, whereas for polycyclic aromatic hydrocarbons such as pyrene, the slowly desorbing, stronger-bound fraction is also important.