Nonlinearity of Cationic Aromatic Amine Sorption to Aluminosilicates and Soils: Role of Intermolecular Cation鈭捪€ Interactions

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• 作者：Dharni Vasudevan ; Teresa A. Arey ; Daniel R. Dickstein ; Mark H. Newman ; Tina Y. Zhang ; Heather M. Kinnear ; Mohammad M. Bader
• 刊名：Environmental Science & Technology
• 出版年：2013
• 出版时间：December 17, 2013
• 年：2013
• 卷：47
• 期：24
• 页码：14119-14127
• 全文大小：396K
• 年卷期：v.47,no.24(December 17, 2013)
• ISSN：1520-5851

文摘

Through the study of substituted anilines and benzylamines, we demonstrated that cooperative cation鈭捪€, 蟺鈥撓€, and van der Waals interactions can increase aromatic cationic amine sorption to Na/Ca-montmorillonite well beyond the extent expected by cation exchange alone. Cationic amines exhibiting cooperative interactions displayed nonlinear S-shaped isotherms and increased affinity for the sorbent at low surface coverage; parallel cation exchange and cooperative interactions were noted above a sorption threshold of 0.3鈥?.3% of exchange sites occupied. Our experiments revealed the predominance of intermolecular cation鈭捪€ interactions, which occurred between the 蟺 system of a compound retained on the surface via cation exchange and the cationic amine group of an adjacent molecule. Compounds with greater amine charge/area and electron-donating substituents that allowed for greater electron density at the center of the aromatic ring showed a greater potential for cation鈭捪€ interactions on montmorillonite surfaces. However, benzylamine sorption to nine soils, at charge loadings comparable to the experiments with montmorillonite, revealed no significant cooperative interactions. It appears that cation鈭捪€ interactions may be likely in soils with exceptionally high cation exchange capacities (>0.7 mol charge/kg) and low organic matter contents, abundant in montmorillonite and other expanding clay minerals.