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International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472 EISSN: 1735-1472
Vol. 13, No. 5, 2016, pp. 1329-1334
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Bioline Code: st16126
Full paper language: English
Document type: Research Article
Document available free of charge
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International Journal of Environment Science and Technology, Vol. 13, No. 5, 2016, pp. 1329-1334
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Nitrite reduction by Fe(II) associated with kaolinite
Rakshit, S.; Matocha, C. J.; Coyne, M. S. & Sarkar, D.
Abstract
Interactions of iron (Fe) with the nitrogen
(N) cycle have emerged and contain elements of abiotic and
biological reactions. One such abiotic reaction which has
received little study is the reactivity of NO2- and Fe(II)
associated with a major clay mineral, kaolinite. The main
objective of this study was to evaluate the reactivity of NO2-
with Fe(II) added to kaolinite under anoxic conditions. Stirred
batch reactivity experiments were carried out with
10 g L-1 kaolinite spiked with 25 and 100 µM Fe(II) at pH
6.45 in an anaerobic chamber. Approximately 500 µM NO2-
was added to initiate the reaction with Fe(II)-loaded kaolinite.
The rate of nitrite removal from solution was 2.4-fold
slower in the high Fe(II) treatment when compared with the
low Fe(II) treatment. A large portion of the NO2- removed
from solution was confirmed to be reduced to N2O(g) in the
Fe(II)-kaolinite slurries. However, NO2- reduction was also
noticed in the presence of kaolinite-alone and to somewhat
lesser extent in the presence of dithionite-citrate-bicarbonate
(DCB)-treated kaolinite. Chemical extractions coupled with
infrared spectroscopy suggest that Fe(III) oxide mineral
impurities and structural Fe(III) in kaolinite may participate
in NO2- removal from solution. Furthermore, a magnetite
mineral was identified based on X-ray diffraction analysis of
untreated kaolinite and DCB-treated kaolinite. Our findings
reveal a novel pathway of NO2- transformation in the
environment in the presence of Fe(II) associated (sorbed and
impurity) with kaolinite.
Keywords
Nitrite reduction; Anaerobic; Abiotic XRD; SEM
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