Simultaneous Sequestration of Humic Acid-Complexed Pb(II), Zn(II), Cd(II), and As(V) by Sulfidated Zero-Valent Iron: Performance and Stability of Sequestration Products

Heavy metal(loid)s (HMs) such as Pb(II), Zn(II), Cd(II), and As(V) are ubiquitously present in co-contaminated soil and shallow groundwater, where the humic acid (HA)-rich environments can significantly influence their sequestration. In this study, sulfidated zero-valent iron (S-ZVI) was found to be...

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Bibliographic Details
Published in:Environmental science & technology 2022-03, Vol.56 (5), p.3127-3137
Main Authors: Liu, Yang, Qiao, Junlian, Sun, Yuankui, Guan, Xiaohong
Format: Article
Language:English
Subjects:
Cadmium
Corrosion
Fine structure
Groundwater
Heavy metals
Humic acids
Humic Substances
Hydroxides
Iron
Iron - chemistry
Lag phase
Lead
Metal sulfides
Photoelectron spectroscopy
Photoelectrons
Reaction kinetics
Sediment pollution
Soil contamination
Soil pollution
Solid phases
Structural analysis
Sulfur
Ultrastructure
Water Pollutants, Chemical - chemistry
X ray absorption
Zinc
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Summary:Heavy metal(loid)s (HMs) such as Pb(II), Zn(II), Cd(II), and As(V) are ubiquitously present in co-contaminated soil and shallow groundwater, where the humic acid (HA)-rich environments can significantly influence their sequestration. In this study, sulfidated zero-valent iron (S-ZVI) was found to be able to simultaneously sequestrate these HA-complexed HMs. Specially, the HA-complexed Pb(II), Zn(II), Cd(II), and As(V) could be completely removed by S-ZVI within 60 min, while only 35-50% of them could be sequestrated within 72 h by unsulfidated ZVI. Interestingly, different from the S-ZVI corrosion behavior, the kinetics of HM sequestration by S-ZVI consisted of an initial slow reaction stage (or a lag phase) and then a fairly rapid reaction process. Characterization results indicated that forming metal sulfides controlled the HM sequestration at the first stage, whereas the enhanced ZVI corrosion and thus-improved adsorption and/or coprecipitation by iron hydroxides governed the second stage. Both metal-oxygen and metal-sulfur bonds in the solid phase could be confirmed by X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis. Moreover, the transformation of S species from SO , SO , and S to S under reducing conditions could allow the sequestrated HMs to remain stable over a long period.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.1c07731