Issue 8, 2022

Interaction of pyrite with zerovalent iron with superior reductive ability via Fe(ii) regeneration

Abstract

Sulfidation of zero-valent iron (SZVI) emerged as a promising approach to enhance both the reactivity and selectivity of nano zero-valent iron (ZVI). However, the dense base layer of the Fe0 core–FeSx shell structure inhibited the Fe(II) regeneration and the applicable pH range was narrow (only acidic conditions), thus limiting the application of SZVI. In this work, a structure with a substrate of pyrite and well dispersed ZVI (FeS2/ZVI) was developed. The interaction of pyrite with Fe0 significantly promoted the generation of Fe2+. More than 99.9% of Cr(VI) (50 mg L−1) was removed within 2 h, which was 3.7–8.9 times higher than that of the precursor alone. During Cr(VI) removal, Fe0 and FeS2 reacted with Fe3+ to regenerate Fe2+ and H+, promoting the Cr(VI) reduction and extending the applicable pH range to 3.04–9.20. Moreover, the effects of S species (S22−, S2−, and S0) in sulfide precursors on the crystal structure, electron transfer capacity, and Fe(II) cycling ability of SZVI were further revealed. The introduced S22− promoted the formation of a galvanic couple between FeS2 (+0.35 V) and Fe0 (−0.44 V), thus accelerating the electron transfer from ZVI and releasing more Fe(II) for Cr(VI) reduction. This study developed an efficient approach for ZVI activation and contributed to the insight into the enhanced mechanism of incorporated sulfur.

Graphical abstract: Interaction of pyrite with zerovalent iron with superior reductive ability via Fe(ii) regeneration

Supplementary files

Article information

Article type
Paper
Submitted
11 Apr 2022
Accepted
13 Jun 2022
First published
24 Jun 2022

Environ. Sci.: Nano, 2022,9, 2713-2725

Interaction of pyrite with zerovalent iron with superior reductive ability via Fe(II) regeneration

Q. Li, Z. Jiang, J. Zheng, Y. Xie, Q. Liao, F. Zhao, Z. Yang, Z. Lin, M. Si and W. Yang, Environ. Sci.: Nano, 2022, 9, 2713 DOI: 10.1039/D2EN00349J

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