Switchable Ionic Liquids: An Environmentally Friendly Medium to Synthesise Nanoparticulate Green Rust

Journal Article · Mon Jun 27 00:00:00 EDT 2016 · Current Inorganic Chemistry

DOI:https://doi.org/10.2174/1877944106999160317160621· OSTI ID:1290387

Lao, David; Kukkadapu, Ravi; Kovarik, Libor; Arey, Bruce; Heldebrant, David; Nune, Satish

Under anoxic conditions, a novel nanoparticulate green rust with carbonate (nano GR) was synthesized by addition of methanol to degassed switchable ionic liquid (SWIL) solution comprised of 1-hexanol, diazabicycloundec-7-ene (DBU), CO2 and Fe(C2H3O2)2 (Fe(OAc)2). Variable temperature Mössbauer spectroscopy studies indicated the product to be predominantly GR while TEM-SAED method confirmed it be nanoparticulate in nature. Experiments with and without methanol in the SWIL medium suggest that methanol may be responsible for Fe(II) oxidation to Fe(III) necessary for GR formation. Studies with Ar instead of CO2 trigger gas indicated that CO2 is essential for GR formation. Conditions to generate CO32- anion was most likely provided by basic environment of the medium. The nano GR suspension was very reactive and instantaneously oxidized completely to a reddish-brown precipitate upon exposure to ambient atmosphere. The nature of the oxidized sample is not certain. The oxidized product, however, appears to be a mix of ferric green rust- [GR(CO32-]*; major] and ferrihydrite-like minerals. To our knowledge, this is first report of use of environmentally-friendly SWIL reagents to synthesize very reactive nano GR materials.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1290387
• Report Number(s): PNNL-SA-110524
• Journal Information: Current Inorganic Chemistry, Vol. 6, Issue 2; ISSN 1877-9441
• Country of Publication: United States
• Language: English