Journal
SEPARATION AND PURIFICATION TECHNOLOGY
Volume 275, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.seppur.2021.119146
Keywords
Graphene; Biochar; Nanoscale zero-valent-iron; Enhanced reduction; Electron transfer
Categories
Funding
- National Natural Science Foundation of China [21707090]
- Chinese Postdoctoral Science Foundation [2017M611590]
- Shanghai Natural Science Foundation [14ZR1428900]
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This study investigated the removal efficiency of nitrobenzene by nano zero-valent iron/graphene/biochar composite modified with graphene. The results showed that graphene modification enhanced the reduction capacity of the composite, increasing the removal efficiency by releasing electrons to attack nitrobenzene molecules.
To enhance the reduction capacity of nanoscale zero-valent-iron/biochar (nZVI/BC), novel composites modified by graphene (nZVI/GBC) were synthesized. The characterization demonstrated that nZVI/GBC-0.1 had larger specific surface area, higher graphitization level, more carbon defects and functional groups than nZVI/BC. The maximal nitrobenzene (NB) removal efficiency obtained by nZVI/GBC-0.1 was 71.7%, and the reduction removal increased by 2.64 times compared to nZVI/BC. XPS analysis revealed that carbon defect caused by graphene modification played a key role in the NB removal process. Furthermore, the electrochemical experiments demonstrated that graphene increased the current density in nZVI/GBC and the potential difference between nZVI and BC, and reduced the equivalent series resistance of nZVI/GBC. Accordingly, the electron releasing capacity could be enhanced. Then the electrons from nZVI/GBC composite could attack the -NO2 on NB to form AN. Also, Fe2+ could reduce NB by donating electron. Moreover, among the functional groups on the surface of nZVI/GBC, the C-OH group was the main electron-donating group that could reduce Fe3+ to Fe2+. These findings provided insights for exploring the mechanism of improving the reduction capacity of nZVI/GBC composite.
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