@article {47813,
	title = {Na-montmorillonite to Fe(II)-Mt using ferrous citrate/ascorbate obtained by dissolving iron powder},
	journal = {Applied Clay Science},
	volume = {217},
	year = {2022},
	month = {FEB},
	pages = {106396},
	type = {Article},
	abstract = {Bentonite containing montmorillonite (Mt) as the major clay mineral is the potential buffer material of engineered barrier system in the deep geological repository for high-level waste management. The corrosion products of canister/or overpack material (carbon steel) may alter the basic characteristics of bentonite through Fe/clay interaction and formation of FeMt to certain extent. A convenient method is required for quantitative preparation of Fe(II)-Mt because the only few direct methods reported have some limitations. For this, weak ferrous complexes having good solubility to facilitate the cation-exchange with bentonite is essential. Therefore, Fe(II)-citrate, Fe(II)-ascorbate and Fe(II)-citrate/ascorbate were obtained here by dissolving the iron powder (Fe0) in citric acid (CA), ascorbic acid (AA) and their equimolar mixtures from 25~mM to 300~mM at 70~{\textdegree}C under N2 atmosphere. The redox potential was measured to monitor the dissolution of Fe0 in these mild organic acids. Higher dissolution of Fe0 occurred in CA~+~AA mixture. The dissolved iron in the form of ferrous complex was reasonably stable in inert atmosphere, Fe2+/Fetotal~≈~1. The parent clay mineral (bentonite, NaMt) was treated with Fe(II)~-~cit/asc to form Fe(II)~-~Mt. through cation exchange process. The CEC and ferrous to ferric ratio of the Fe(II)-Mt was close to the stoichiometric amount. The XRF, XRD, ac impedance, FT-IR, TGA/DSC, XPS and FE-SEM are used for further characterization. In-situ complexation reaction of interlayer Fe2+ ions in Fe(II)-Mt with o-phenanthroline was also observed.},
	keywords = {Ascorbic acid, Bentonite, Citric acid, Cr(VI) reduction, Fe(II)-montmorillonite, Iron dissolution},
	issn = {0169-1317},
	doi = {10.1016/j.clay.2021.106396},
	author = {S. Chikkamath and J. Manjanna and N. Momin and B.G. Hegde and G.P. Nayaka and Aishwarya S. Kar and B.S. Tomar}
}
