Hydrophobic sulfur core–shell layered metallic iron for nitrate reduction with nearly 100% dinitrogen selectivity: Mechanism and field studies

Choe Earn Choong, So Yeon Yoon, Kien Tiek Wong, Minhee Kim, Gooyong Lee, Sang Hyoun Kim, Byong Hun Jeon, Jaeyoung Choi, Yeomin Yoon, Eun Ha Choi, Min Jang

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

We prepared hydrophobic sulfur (S) core–shell-layered nano-zero-valent iron (Fe) (S-nZVI) via a post-sulfidation method with varying Fe/S mass ratios for NO3 reduction. Notably, S0.125ZVI (Fe/S = 0.125) showed good N[sbnd]O cleavage properties owing to its high electron (e) transfer efficiency and low surface passivation. As a result, the S0.125ZVI exhibited higher selectivity of NO3 reduction toward N2 than sole nZVI in synthetic and actual NO3 groundwater in batch experiments. Density functional theory (DFT) calculations showed that H2 evolution over S-nZVI was suppressed by the S atom in the hollow site of the Fe(1 1 0) surface, resulting in nearly 100 % denitrification selectivity. Quenching tests revealed that e transfer through the S atom toward the surface bounded by NOx species is the dominant denitrification mechanism of S-nZVI. Up-flow column tests using actual groundwater were conducted for 127 d, and S0.125ZVI demonstrated a removal capacity of up to 1907 mg-N/g NO3. Field experiments using S0.125ZVI for NO3-contaminated groundwater remediation were conducted over four months, confirming that S-nZVI may be an alternative to nZVI for in situ groundwater remediation.

Original languageEnglish
Article number140083
JournalChemical Engineering Journal
Volume454
DOIs
StatePublished - 15 Feb 2023

Bibliographical note

Funding Information:
This work was supported by the by Korea Environment Industry & Technology Institute (Grant 2018002480006) and National Research Foundation (NRF) funded by the Ministry of Education (2021R1A6A1A03038785).

Publisher Copyright:
© 2022

Keywords

  • Field test
  • Nitrate reduction
  • Sulfur
  • Zero-valent iron

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