期刊
APPLIED CLAY SCIENCE
卷 49, 期 3, 页码 120-126出版社
ELSEVIER
DOI: 10.1016/j.clay.2010.04.014
关键词
Adsorption; Bentonite; Ethofumesate; Moroccan clays; Cosolvents; Environmental settings
资金
- Agencia Espanola de Cooperacion Internacional para el Desarrollo (AECID) [60/04/P/E]
- AECID
The adsorption of the slightly hydrophobic herbicide ethofumesate (Kow = 2.70) by a bentonite and a common clay from Morocco was studied in water and in the presence of different cosolvents (methanol, hexane and dissolved organic matter (DOM)). The bentonite (SC) and the clay (NSC) were used in both a raw and modified state by the addition of long-chain quaternary ammonium ions (tetramethylammonium TMA, octyl trimethylammonium OTMA and octadecyl trimethylammonium ODTMA). The Freundlich adsorption coefficients (Kf) of ethofumesate by TMA- and OTMA-clays in water increased significantly (8.5-93 fold (SC) and 2-12 fold (NSC)) in relation to raw clays. This was more evident for ODTMA-clays (1100 fold (SC) and 290 fold (NSC)). The adsorption capacities were lower for modified NSC and increased with the organic carbon content. Different interactions between adsorbate-solvent and adsorbate-adsorbent were established with cosolvents, but when they were present in the clay-water system a decrease in adsorption was seen in general. Adsorption decreased 4-7-fold (TMA-clays), 3.2-fold (OTMA-clays) and 2.4-2.8-fold (ODTMA-clays) in the presence of methanol. No significant change was seen in the adsorption by ODTMA-clays in presence of hexane, although a marked decrease occurred in this system for the adsorption by TMA-clays (no adsorption) and OTMA-clays (22-fold). No significant variation in adsorption was observed in the presence of DOM. The results indicated that the enhanced adsorption of ethofumesate by organic cation-exchanged clays in water can be significantly changed in the presence of different cosolvents. This has serious environmental implications for pesticide adsorption by modified bentonites and clays in the presence of organic solvents. (C) 2010 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据