Ferrihydrite transformation under the impact of humic acid and Pb: kinetics, nanoscale mechanisms, and implications for C and Pb dynamics

Author(s): Yang Lu ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Shiwen Hu ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Zimeng Wang ⁶ ^, ⁷ ^, ⁸ ^, ⁴ , Yang Ding ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Guining Lu ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Zhang Lin ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Zhi Dang ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ , Zhenqing Shi ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵

Publication date (Electronic): 2019

Journal: Environmental Science: Nano

Publisher: Royal Society of Chemistry (RSC)

Read this article at

ScienceOpenPublisher

Bookmark

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

We, at nanoscale, demonstrated a visualized description of ferrihydrite transformation to crystalline Fe oxides under the impact of Pb and HA.

Abstract

Precipitation of Fe( iii) happens very fast across the redox gradient from anoxic to oxic environments and is usually coupled with the co-precipitation of humic acids (HAs) and heavy metals such as Pb. Most previous studies focused on the sorption behaviors of Pb to static phases of Fe oxides or HA. However, little is known about the dynamic interactions between Fe oxides, HA, and Pb. In this study, we presented a systematic, quantitative, and visualized description of ferrihydrite aging and transformation to crystalline Fe oxides under the impact of Pb and HA in abiotic conditions. Wet chemistry experiments were seamlessly complemented by time-resolved chemical imaging with spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) equipped with energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). Results showed that the presence of HA and Pb slowed down the process of ferrihydrite transformation to hematite. STEM results demonstrated that HA and Pb addition resulted in hematite nanoparticles with a loose and porous structure in comparison with the compact structure of pure hematite nanoparticles. In addition to surface adsorption, EDS mapping and EDS/EELS line scan profiles unambiguously showed that both HA molecules and Pb ions penetrated into the loose, porous structure of hematite nanoparticles, which may act as an important but underappreciated pathway for C and Pb sequestration given the high frequency of Fe oxide transformation in terrestrial ecosystems. Results help to elucidate the environmental behavior of C and Pb during the Fe oxide transformation processes and also shed light on nanoscale mechanisms of organic matter interactions with Fe oxides.

Related collections

Most cited references 93

Record: found
Abstract: found
Article: not found

Persistence of soil organic matter as an ecosystem property.

Michael W. I. Schmidt, Margaret S Torn, Samuel Abiven … (2012)

Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily--and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming.

0 comments Cited 657 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: not found
Article: not found

A profile refinement method for nuclear and magnetic structures

H. Rietveld (1969)

0 comments Cited 638 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Cryo-STEM mapping of solid–liquid interfaces and dendrites in lithium-metal batteries

Zhengyuan Tu, Michael J. Zachman, Snehashis Choudhury … (2018)

Solid-liquid interfaces are important in a range of chemical, physical and biological processes1-4, but are often not fully understood owing to the lack of high-resolution characterization methods that are compatible with both solid and liquid components5. For example, the related processes of dendritic deposition of lithium metal and the formation of solid-electrolyte interphase layers6,7 are known to be key determinants of battery safety and performance in high-energy-density lithium-metal batteries. But exactly what is involved in these two processes, which occur at a solid-liquid interface, has long been debated8-11 because of the challenges of observing such interfaces directly. Here we adapt a technique that has enabled cryo-transmission electron microscopy (cryo-TEM) of hydrated specimens in biology-immobilization of liquids by rapid freezing, that is, vitrification12. By vitrifying the liquid electrolyte we preserve it and the structures at solid-liquid interfaces in lithium-metal batteries in their native state, and thus enable structural and chemical mapping of these interfaces by cryo-scanning transmission electron microscopy (cryo-STEM). We identify two dendrite types coexisting on the lithium anode, each with distinct structure and composition. One family of dendrites has an extended solid-electrolyte interphase layer, whereas the other unexpectedly consists of lithium hydride instead of lithium metal and may contribute disproportionately to loss of battery capacity. The insights into the formation of lithium dendrites that our work provides demonstrate the potential of cryogenic electron microscopy for probing nanoscale processes at intact solid-liquid interfaces in functional devices such as rechargeable batteries.