Mechanisms for strong adsorption of tetracycline to carbon nanotubes: A comparative study using acti

时间：2009-04-18  阅读：    我要评论:

Liangliang Ji^†, Wei Chen^‡, Lin Duan^‡ and Dongqiang Zhu*^† State Key Laboratory of Pollution Control and Resource Reuse/School of the Environment, Nanjing University, Jiangsu 210093, China, and Tianjin Key Laboratory of Environmental Remediation and Pollution Control/College of Environmental Science and Engineering, Nankai University, Tianjin 300071, ChinaEnviron. Sci. Technol., 2009, 43 (7), pp 2322–2327DOI: 10.1021/es803268bPublication Date (Web): February 27, 2009Copyright © 2009 American Chemical Society †

Nanjing University.

, ‡

Nankai University.

, * Corresponding author phone: +86 025-8359-6496; email: zhud@nju.edu.cn.

Abstract

Significant concerns have been raised over the presence of antibiotics including tetracyclines in aquatic environments. We herein studied single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT) as potential effective adsorbents for removal of tetracycline from aqueous solution. In comparison, a nonpolar adsorbate, naphthalene, and two other carbonaceous adsorbents, pulverized activated carbon (AC) and nonporous graphite, were used. The observed adsorbent-to-solution distribution coefficient (K_d, L/kg) of tetracycline was in the order of 10⁴−10⁶ L/kg for SWNT, 10³−10⁴ L/kg for MWNT, 10³−10⁴ L/kg for AC, and 10³−10⁵ L/kg for graphite. Upon normalization for adsorbent surface area, the adsorption affinity of tetracycline decreased in the order of graphite/SWNT > MWNT AC. The weaker adsorption of tetracycline to AC indicates that for bulky adsorbates adsorption affinity is greatly affected by the accessibility of available adsorption sites. The remarkably strong adsorption of tetracycline to the carbon nanotubes and to graphite can be attributed to the strong adsorptive interactions (van der Waals forces, π−π electron-donor−acceptor interactions, cation-π bonding) with the graphene surface. Complexation between tetracycline and model graphene compounds (naphthalene, phenanthrene, pyrene) in solution phase was verified by ring current-induced ¹H NMR upfield chemical shifts of tetracycline moieties.

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