Monodisperse amino-modified nanosized zero-valent iron for selective and recyclable removal of TNT: Synthesis, characterization, and removal mechanism |
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Authors: | Jing Li Qingxiang Zhou Miao Li Yongli Liu Qinan Song |
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Institution: | 1. School of Environment, Tsinghua University, Beijing 100084, China;2. State Key Laboratory of Heavy Oil Processing, State Key Laboratory of Petroleum Pollution Control, College of Chemical Engineering and Environment, China University of Petroleum Beijing, Beijing 102249, China;3. School of Environment, Henan Normal University, Xinxiang, Henan 453007, China |
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Abstract: | Nitroaromatic explosives are major pollutants produced during wars that cause serious environmental and health problems. The removal of a typical nitroaromatic explosive, 2,4,6-trinitrotoluene (TNT), from aqueous solution, was conducted using a new recyclable magnetic nano-adsorbent (email protected]2 NH2). This adsorbent was prepared by grafting amino groups onto email protected]2 particles with a well-defined core-shell structure and demonstrated monodispersity in solution. The removal performance of the nano-adsorbent towards TNT was found to be 2.57 and 4.92 times higher than that towards two analogous explosives, 2,4-dinitrotoluene (2,4-DNT) and 2-nitrotoluene (2-NT), respectively, under neutral conditions. The difference in the removal performance among the three compounds was further compared in terms of the effects of different conditions (pH value, ionic strength, humic acid concentration, adsorbent modification degree and dosage, etc.) and the electrostatic potential distributions of the three compounds. The most significant elevation is owing to modification of amino on email protected]2 which made a 20.7% increase in adsorption efficiency of TNT. The experimental data were well fit by the pseudo-second-order kinetic model and the Freundlich adsorption isotherm model, indicating multilayer adsorption on a heterogeneous surface. The experimental results and theoretical considerations show that the interactions between email protected]2 NH2 NPs and TNT correspond to dipole-dipole and hydrophobic interactions. These interactions should be considered in the design of an adsorbent. Furthermore, the adaptability to aqueous environment and excellent regeneration capacity of email protected]2 NH2 NPs makes these remediation materials promising for applications. |
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Keywords: | Corresponding authors Nanosized zero-valent iron particles (NZVIs) 2 4 6-trinitrotoluene (TNT) Removal Mechanism Regeneration |
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