Competitive Sorption Used To Probe Strong Hydrogen Bonding Sites for Weak Organic Acids on Carbon Nanotubes

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• 作者：Xiaoyun Li ; Beatriz G谩miz ; Yiquan Wang ; Joseph J. Pignatello ; Baoshan Xing
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：February 3, 2015
• 年：2015
• 卷：49
• 期：3
• 页码：1409-1417
• 全文大小：440K
• ISSN：1520-5851

文摘

We recently proposed that weak acids (AH) adsorb to partially oxidized carbonaceous materials in part by forming strong hydrogen bonds with acidic surface groups, depicted by (A路路路H路路路O鈥搒urf)^{鈭?/sup>, known as negative charge-assisted hydrogen bonds, (鈭?CAHBs. Here we use competition experiments to show that sorption of AH on carbon nanotubes (CNTs) can be described conceptually by a dual specific/nonspecific domain model, where one domain involves (鈭?CAHB sites that can become saturated. The trends observed in single-solute adsorption, including the stoichiometric release of hydroxide upon sorption of carboxyate or phenolate anions, were consistent with trends in the previous studies and pointed to the formation of (鈭?CAHB. 3,4-Dinitrophenolate formed (鈭?CAHBs more efficiently than did 2,6-dichloro-4-nitrophenolate because of alleviation of steric hindrance to approach by the ortho chlorines. Competition against a (鈭?CAHB-capable target compound was greater when the competitor was also (鈭?CAHB-capable than when it was not (e.g., benzoate as target vs 3,4-dinitrophenolate or nitrobenzene as competitor; mono-n-butyl phthalate as target vs methyl benzoate or p-tolyl acetate as competitor). Experiments also revealed competition between the nitroaromatic species for 蟺鈥撓€ electron donor鈥揳cceptor sites. The findings will contribute to a better understanding of the adsorption mechanism of ionizable compounds on carbonaceous materials.}