Further insights into the Fe( ii ) reduction of 2-line ferrihydrite: a semi in situ and in situ TEM study
[1];
[3];
[4];
[5];
- Liaoning Engineering Research Center for Treatment and Recycling of Industrially Discharged Heavy Metals, Shenyang University of Chemical Technology, Shenyang, China, Department of Geological Sciences
- Liaoning Engineering Research Center for Treatment and Recycling of Industrially Discharged Heavy Metals, Shenyang University of Chemical Technology, Shenyang, China
- Physical and Computational Science Directorate, Pacific Northwest National Laboratory, Richland, USA
- Environmental and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, USA
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
The biotic or abiotic reduction of nano-crystalline 2-line ferrihydrite (2-line FH) into more thermodynamically stable phases such as lepidocrocite-LP, goethite-GT, magnetite-MG, and hematite-HT plays an important role in the geochemical cycling of elements and nutrients in aqueous systems. Here, we employed the use of in situ liquid cell (LC) and semi in situ analysis in an environmental TEM to gain further insights at the micro/nano-scale into the reaction mechanisms by which Fe(II)(aq) catalyzes 2-line FH. We visually observed for the first time the following intermediate steps: (1) formation of round and wire-shaped precursor nano-particles arising only from Fe(II)(aq), (2) two distinct dissolution mechanisms for 2 line-FH (i.e. reduction of size and density as well as breakage through smaller nanoparticles), (3) lack of complete dissolution of 2-line FH (i.e. “induction-period”), (4) an amorphous phase growth (“reactive-FH/labile Fe(III) phase”) on 2 line-FH, (5) deposition of amorphous nano-particles on the surface of 2 line-FH and (6) assemblage of elongated crystalline lamellae to form tabular LP crystals. Furthermore, we observed phenomena consistent with the movement of adsorbate ions from solution onto the surface of a Fe(III)-oxy/hydroxide crystal. Thus our work here reveals that the catalytic transformation of 2-line FH by Fe(II)(aq) at the micro/nano scale doesn't simply occur via dissolution– reprecipitation or surface nucleation–solid state conversion mechanisms. Rather, as we demonstrate here, it is an intricate chemical process that goes through a series of intermediate steps not visible through conventional lab or synchrotron bulk techniques. However, such intermediate steps may affect the environmental fate, bioavailability, and transport of elements of such nano-particles in aqueous environments.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory (EMSL); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry
- Sponsoring Organization:
- National Key Research and Development Program of China; National Natural Science Foundation of China (NSFC); USDOE Office of Science (SC), Biological and Environmental Research (BER); USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- 48770; AC02-05CH11231; AC05-76RL01830; 184573
- OSTI ID:
- 1669153
- Alternate ID(s):
- OSTI ID: 1774123
- Report Number(s):
- PNNL-SA-150517; NAADAI
- Journal Information:
- Nanoscale Advances, Journal Name: Nanoscale Advances Vol. 2 Journal Issue: 10; ISSN 2516-0230
- Publisher:
- Royal Society of Chemistry (RSC)Copyright Statement
- Country of Publication:
- United Kingdom
- Language:
- English
Similar Records
Labile Fe(III) supersaturation controls nucleation and properties of product phases from Fe(II)-catalyzed ferrihydrite transformation
Understanding the Importance of Labile Fe(III) during Fe(II)-Catalyzed Transformation of Metastable Iron Oxyhydroxides