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Title: Synthesis of nanometer-sized fayalite and magnesium-iron(II) mixture olivines

Abstract

Olivines are divalent orthosilicates with important geologic, biological, and industrial significance and are typically comprised of mixtures of Mg2+ and Fe2+ ranging from forsterite (Mg2SiO4) to fayalite (Fe2SiO4). Investigating the role of Fe(II) in olivine reactivity requires the ability to synthesize olivines that are nanometer-sized, have different percentages of Mg2+ and Fe2+, and have good bulk and surface purity. This article demonstrates a new method for synthesizing nanosized fayalite and Mg-Fe mixture olivines. First, carbonaceous precursors are generated from sucrose, PVA, colloidal silica, Mg2+, and Fe3+. Second, these precursors are calcined in air to burn carbon and create mixtures of Fe(III)-oxides, forsterite, and SiO2. Finally, calcination in reducing CO-CO2 gas buffer leads to Fe(II)-rich olivines. XRD, Mössbauer, and IR analyses verify good bulk purity and composition. XPS indicates that surface iron is in its reduced Fe(II) form, and surface Si is consistent with olivine. SEM shows particle sizes predominately between 50 and 450 nm, and BET surface areas are 2.8-4.2 m2/g. STEM HAADF analysis demonstrates even distributions of Mg and Fe among the available M1 and M2 sites of the olivine crystals. These nanosized Fe(II)-rich olivines are suitable for laboratory studies with in situ probes that require mineral samples withmore » high reactivity at short timescales.« less

Authors:
; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1422289
Report Number(s):
PNNL-SA-131663
Journal ID: ISSN 0021-9797; 47824; KC0302060
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Colloid and Interface Science; Journal Volume: 515; Journal Issue: C
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Qafoku, Odeta, Ilton, Eugene S., Bowden, Mark E., Kovarik, Libor, Zhang, Xin, Kukkadapu, Ravi K., Engelhard, Mark H., Thompson, Christopher J., Schaef, Herbert T., McGrail, Bernard Peter, Rosso, Kevin M., and Loring, John S. Synthesis of nanometer-sized fayalite and magnesium-iron(II) mixture olivines. United States: N. p., 2018. Web. doi:10.1016/j.jcis.2018.01.036.
Qafoku, Odeta, Ilton, Eugene S., Bowden, Mark E., Kovarik, Libor, Zhang, Xin, Kukkadapu, Ravi K., Engelhard, Mark H., Thompson, Christopher J., Schaef, Herbert T., McGrail, Bernard Peter, Rosso, Kevin M., & Loring, John S. Synthesis of nanometer-sized fayalite and magnesium-iron(II) mixture olivines. United States. doi:10.1016/j.jcis.2018.01.036.
Qafoku, Odeta, Ilton, Eugene S., Bowden, Mark E., Kovarik, Libor, Zhang, Xin, Kukkadapu, Ravi K., Engelhard, Mark H., Thompson, Christopher J., Schaef, Herbert T., McGrail, Bernard Peter, Rosso, Kevin M., and Loring, John S. Sun . "Synthesis of nanometer-sized fayalite and magnesium-iron(II) mixture olivines". United States. doi:10.1016/j.jcis.2018.01.036.
@article{osti_1422289,
title = {Synthesis of nanometer-sized fayalite and magnesium-iron(II) mixture olivines},
author = {Qafoku, Odeta and Ilton, Eugene S. and Bowden, Mark E. and Kovarik, Libor and Zhang, Xin and Kukkadapu, Ravi K. and Engelhard, Mark H. and Thompson, Christopher J. and Schaef, Herbert T. and McGrail, Bernard Peter and Rosso, Kevin M. and Loring, John S.},
abstractNote = {Olivines are divalent orthosilicates with important geologic, biological, and industrial significance and are typically comprised of mixtures of Mg2+ and Fe2+ ranging from forsterite (Mg2SiO4) to fayalite (Fe2SiO4). Investigating the role of Fe(II) in olivine reactivity requires the ability to synthesize olivines that are nanometer-sized, have different percentages of Mg2+ and Fe2+, and have good bulk and surface purity. This article demonstrates a new method for synthesizing nanosized fayalite and Mg-Fe mixture olivines. First, carbonaceous precursors are generated from sucrose, PVA, colloidal silica, Mg2+, and Fe3+. Second, these precursors are calcined in air to burn carbon and create mixtures of Fe(III)-oxides, forsterite, and SiO2. Finally, calcination in reducing CO-CO2 gas buffer leads to Fe(II)-rich olivines. XRD, Mössbauer, and IR analyses verify good bulk purity and composition. XPS indicates that surface iron is in its reduced Fe(II) form, and surface Si is consistent with olivine. SEM shows particle sizes predominately between 50 and 450 nm, and BET surface areas are 2.8-4.2 m2/g. STEM HAADF analysis demonstrates even distributions of Mg and Fe among the available M1 and M2 sites of the olivine crystals. These nanosized Fe(II)-rich olivines are suitable for laboratory studies with in situ probes that require mineral samples with high reactivity at short timescales.},
doi = {10.1016/j.jcis.2018.01.036},
journal = {Journal of Colloid and Interface Science},
number = C,
volume = 515,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2018},
month = {Sun Apr 01 00:00:00 EDT 2018}
}