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Title: Biological Redox Cycling Of Iron In Nontronite And Its Potential Application In Nitrate Removal

Abstract

Redox cycling of structural Fe in phyllosilicates provides a potential method to remediate nitrate contamination in natural environment. Past research has only studied chemical redox cycles or a single biologically mediated redox cycle of Fe in phyllosilicates. The objective of this research was to study three microbially driven redox cycles of Fe in one phyllosilicate, nontronite (NAu-2). During the reduction phase structural Fe(III) in NAu-2 served as electron acceptor, lactate as electron donor, AQDS as electron shuttle, and dissimilatory Fe(III)-reducing bacteria Shewanella putrefaciens CN32 as mediator in bicarbonate-buffered and PIPES-buffered media. During the oxidation phase, biogenic Fe(II) served an electron donor, nitrate as electron acceptor, and nitrate-dependent Fe(II)-oxidizing bacteria Pseudogulbenkiania sp. strain 2002 as mediator in the same media. For all three cycles, structural Fe in NAu-2 was able to reversibly undergo 3 redox cycles without significant reductive or oxidative dissolution. X-ray diffraction and scanning and transmission electron microscopy revealed that NAu-2 was the dominant residual mineral throughout the 3 redox cycles with some dissolution textures but no significant secondary mineralization. Mössbauer spectroscopy revealed that Fe(II) in bio-reduced samples likely occurred in two distinct environments, at edges and the interior of the NAu-2 structure. Nitrate was completely reduced to nitrogenmore » gas under both buffer conditions and this extent and rate did not change with Fe redox cycles. Mössbauer spectroscopy further revealed that nitrate reduction was coupled to predominant/preferred oxidation of edge Fe(II). These results suggest that structural Fe in phyllosilicates may represent a renewable source to continuously remove nitrate in natural environments.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1182942
Report Number(s):
PNNL-SA-107381
44687; KP1704020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Environmental Science & Technology, 49(9):5493-5501
Additional Journal Information:
Journal Name: Environmental Science & Technology, 49(9):5493-5501
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Zhao, Linduo, Dong, Hailiang, Kukkadapu, Ravi K., Zeng, Qiang, Edelmann, Richard E., Pentrak, Martin, and Agrawal, Abinash. Biological Redox Cycling Of Iron In Nontronite And Its Potential Application In Nitrate Removal. United States: N. p., 2015. Web. doi:10.1021/acs.est.5b00131.
Zhao, Linduo, Dong, Hailiang, Kukkadapu, Ravi K., Zeng, Qiang, Edelmann, Richard E., Pentrak, Martin, & Agrawal, Abinash. Biological Redox Cycling Of Iron In Nontronite And Its Potential Application In Nitrate Removal. United States. doi:10.1021/acs.est.5b00131.
Zhao, Linduo, Dong, Hailiang, Kukkadapu, Ravi K., Zeng, Qiang, Edelmann, Richard E., Pentrak, Martin, and Agrawal, Abinash. Tue . "Biological Redox Cycling Of Iron In Nontronite And Its Potential Application In Nitrate Removal". United States. doi:10.1021/acs.est.5b00131.
@article{osti_1182942,
title = {Biological Redox Cycling Of Iron In Nontronite And Its Potential Application In Nitrate Removal},
author = {Zhao, Linduo and Dong, Hailiang and Kukkadapu, Ravi K. and Zeng, Qiang and Edelmann, Richard E. and Pentrak, Martin and Agrawal, Abinash},
abstractNote = {Redox cycling of structural Fe in phyllosilicates provides a potential method to remediate nitrate contamination in natural environment. Past research has only studied chemical redox cycles or a single biologically mediated redox cycle of Fe in phyllosilicates. The objective of this research was to study three microbially driven redox cycles of Fe in one phyllosilicate, nontronite (NAu-2). During the reduction phase structural Fe(III) in NAu-2 served as electron acceptor, lactate as electron donor, AQDS as electron shuttle, and dissimilatory Fe(III)-reducing bacteria Shewanella putrefaciens CN32 as mediator in bicarbonate-buffered and PIPES-buffered media. During the oxidation phase, biogenic Fe(II) served an electron donor, nitrate as electron acceptor, and nitrate-dependent Fe(II)-oxidizing bacteria Pseudogulbenkiania sp. strain 2002 as mediator in the same media. For all three cycles, structural Fe in NAu-2 was able to reversibly undergo 3 redox cycles without significant reductive or oxidative dissolution. X-ray diffraction and scanning and transmission electron microscopy revealed that NAu-2 was the dominant residual mineral throughout the 3 redox cycles with some dissolution textures but no significant secondary mineralization. Mössbauer spectroscopy revealed that Fe(II) in bio-reduced samples likely occurred in two distinct environments, at edges and the interior of the NAu-2 structure. Nitrate was completely reduced to nitrogen gas under both buffer conditions and this extent and rate did not change with Fe redox cycles. Mössbauer spectroscopy further revealed that nitrate reduction was coupled to predominant/preferred oxidation of edge Fe(II). These results suggest that structural Fe in phyllosilicates may represent a renewable source to continuously remove nitrate in natural environments.},
doi = {10.1021/acs.est.5b00131},
journal = {Environmental Science & Technology, 49(9):5493-5501},
number = ,
volume = ,
place = {United States},
year = {2015},
month = {5}
}