TY - JOUR
T1 - Mechanistic insights into Cr(VI) removal by a combination of zero-valent iron and pyrite
AU - Zhang, Ruiming
AU - Napolano, Rossana
AU - Xi, Beidou
AU - Salazar, Anne Millicent
AU - Shi, Qiantao
AU - Zhao, Ying
AU - Meng, Xiaoguang
N1 - Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/7
Y1 - 2023/7
N2 - Recent studies have revealed that a combination of zero-valent iron (ZVI) and pyrite (FeS2) can effectively remove (Cr(VI)) from water, but the reasons behind this synergistic effect are still unclear. Our batch experiments showed that dissolved oxygen (DO) is a critical factor in the improved removal of Cr(VI) by ZVI and pyrite. When 0.08 g/L pyrite was combined with 0.5 g/L ZVI in the presence of DO, total Cr was reduced from 10 mg/L to 0.02 mg/L within 6 h. Conversely, in the absence of DO, total Cr was only reduced to 5.6 mg/L. DO oxidation of pyrite produced protons that promote ZVI corrosion, and mixing pyrite with water creates dissolved sulfide, which also contributes to the improved removal of Cr(VI). Electron microscopy images and X-ray absorption near edge structure analyses revealed that the presence of dissolved sulfide led to the formation of ferrous sulfide precipitates on the ZVI surface, preventing the formation of a passivating layer.
AB - Recent studies have revealed that a combination of zero-valent iron (ZVI) and pyrite (FeS2) can effectively remove (Cr(VI)) from water, but the reasons behind this synergistic effect are still unclear. Our batch experiments showed that dissolved oxygen (DO) is a critical factor in the improved removal of Cr(VI) by ZVI and pyrite. When 0.08 g/L pyrite was combined with 0.5 g/L ZVI in the presence of DO, total Cr was reduced from 10 mg/L to 0.02 mg/L within 6 h. Conversely, in the absence of DO, total Cr was only reduced to 5.6 mg/L. DO oxidation of pyrite produced protons that promote ZVI corrosion, and mixing pyrite with water creates dissolved sulfide, which also contributes to the improved removal of Cr(VI). Electron microscopy images and X-ray absorption near edge structure analyses revealed that the presence of dissolved sulfide led to the formation of ferrous sulfide precipitates on the ZVI surface, preventing the formation of a passivating layer.
KW - Chromate
KW - Dissolved oxygen
KW - Pyrite
KW - Reduction
KW - Zero valent iron
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U2 - 10.1016/j.chemosphere.2023.138693
DO - 10.1016/j.chemosphere.2023.138693
M3 - Article
C2 - 37060956
AN - SCOPUS:85153334559
SN - 0045-6535
VL - 330
JO - Chemosphere
JF - Chemosphere
M1 - 138693
ER -