Journal
CHEMICAL ENGINEERING JOURNAL
Volume 405, Issue -, Pages -Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2020.126545
Keywords
Chromeium removal; Defects; Edges; Graphite foam; Bioelectrochemical system
Categories
Funding
- China Major Science and Technology Program for Water Pollution Control and Treatment [2017ZX07101003]
- National Natural Science Foundation of China [21961160742]
- Zhejiang Provincial key research and development program [2019C03102]
- China Postdoctoral Science Foundation [2019M662064]
- Ministry Department of Zhejiang Province [Y201534982]
- Department of Energy
- MRCAT
- DOE Advanced Photon Source, Argonne National Laboratory, U.S. Department of Energy, United States [DE-AC02-06CH11357]
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The study showed that the three-dimensional graphite foam formed by liquid nitrogen treatment of graphite paper can enhance the reduction efficiency of Cr(VI) in MFCs, attributed to the porous structures, edges, and O-doped defects on the surface providing more active sites and inhibiting OH- diffusion, leading to a high local pH.
Metal-free electrocatalysts have been widely used as cathodes for the reduction of hexavalent chromium [Cr(VI)] in microbial fuel cells (MFCs). The electrocatalytic activity of such system needs to be increased due to the low anodic potential provided by bacteria. In this study, graphite paper (GP) was treated by liquid nitrogen to form three-dimensional graphite foam (3DGF), improving the Cr(VI) reduction by 17% and the total Cr removal by 81% at 30 h in MFCs. X-ray absorption spectroscopy confirmed the Cr(VI) reduction product as Cr(OH)(3). Through the spectroscopy characterizations, electrochemical measurements, and density functional theory calculations, the porous structures, edges, and O-doped defects on the 3DGF surface resulted in a higher electro-conducting rate and a lower mass transfer rate, which provide more active sites for the Cr(VI) reduction. Additionally, the scrolled graphene-like carbon nanosheets and porous structures on the 3DGF surface might limit the OH- diffusion and result in a high local pH, which accelerated the Cr(OH)(3) formation. The results of this study are expected to provide a simple method to manipulate the carbon materials and insights into mechanisms of Cr(VI) reduction in MFCs by the 3DGF with in situ exfoliated edges and O-functionalized graphene.
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