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Abstract
<p class="first" id="d4983934e101">In this study we reported that the presence of
functionalized multi-walled carbon
nanotubes (FCNT-H) would greatly enhance the degradation of atrazine (ATZ), a model
contaminant, in the Fe(III)-mediated Fenton-like system. Efficient ATZ degradation
(>90%) was achieved within 30 min in the presence of 20 mg.L-1 FCNT-H, 2.0 mg.L-1
Fe(III), and 170 mg.L-1 H2O2, whereas negligible ATZ degradation occurred in FCNT-H
free system. The structure and surface chemistry of FCNT-H and other CNTs were well
characterized. The formed active species were determined based on ESR analysis, and
the mass balance of Fe species during the reaction was monitored. In particular, a
new method based on ferrozine complexation was proposed to track the formed Fe(II).
The results indicated that ATZ was mainly degraded by the generated hydroxyl radical
(HO·), and Fe(III)/Fe(II) cycling was still the rate-limiting step. Besides a small
fraction of Fe(III) reduced by FCNT-H, a new pathway was revealed for fast reduction
of most Fe(III), i.e., reaction of FCNT-H-Fe(III) complexes with H2O2. Comparison
of different CNTs-mediated Fe(III)/H2O2 systems indicated that such enhanced effect
of CNTs mainly resulted from the surface carboxyl group instead of hydroxyl and carbonyl
group. Combined with X-ray photoelectron spectroscopy (XPS) analysis, the electron
density migration from Fe(III) to FCNT-H possibly resulted in the fast reduction of
FCNT-H-Fe(III) complexes by H2O2. This study enables better understanding the enhanced
Fe(III)-mediated Fenton-like reaction in the presence of MWCNTs and thus, will shed
new light on how to develop more efficient similar Fenton systems via Fe(III) complexation.
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