TY - JOUR
T1 - Sulfidation of Zero-Valent Iron by Direct Reaction with Elemental Sulfur in Water
T2 - Efficiencies, Mechanism, and Dechlorination of Trichloroethylene
AU - Cai, Shichao
AU - Chen, Bo
AU - Qiu, Xiaojiang
AU - Li, Jiamei
AU - Tratnyek, Paul G.
AU - He, Feng
N1 - Publisher Copyright:
© 2020 American Chemical Society.
PY - 2021/1/5
Y1 - 2021/1/5
N2 - Sulfidation can enhance both the reactivity and selectivity (i.e., electron efficiency, ϵe) of zero-valent iron (ZVI) in contaminant removal, which may make this technology cost-effective for a wider range of water treatment applications. However, current sulfidation methods involve either hazardous or unstable sulfidation agents (e.g., Na2S, Na2S2O3, and Na2S2O4) or energy-intensive preparations (e.g., mechanochemical sulfidation with elemental sulfur). In this study, we demonstrate that very efficient sulfidation of microscale ZVI (mZVI) can be achieved at all S/Fe molar ratios (μ100% sulfidation efficiency, ϵs) simply by direct reaction between elemental sulfur (S0) and ZVI in an aqueous suspension at ambient temperature. In comparison, the ϵs values obtained using Na2S, Na2S2O3, or Na2S2O4 as the sulfidation agents were only μ23, μ75, and μ38%, respectively. The sulfidated mZVI produced using the new method reacts with trichloroethylene (TCE) with very high rates and electron efficiencies: rate constants and electron efficiencies were 800- and 79-fold higher than those of the unsulfidated mZVI. The enhanced performance of this material, together with the operational advantages of S0 for sulfidation (including safety, stability, and cost), may make it a desirable product for full-scale engineering applications.
AB - Sulfidation can enhance both the reactivity and selectivity (i.e., electron efficiency, ϵe) of zero-valent iron (ZVI) in contaminant removal, which may make this technology cost-effective for a wider range of water treatment applications. However, current sulfidation methods involve either hazardous or unstable sulfidation agents (e.g., Na2S, Na2S2O3, and Na2S2O4) or energy-intensive preparations (e.g., mechanochemical sulfidation with elemental sulfur). In this study, we demonstrate that very efficient sulfidation of microscale ZVI (mZVI) can be achieved at all S/Fe molar ratios (μ100% sulfidation efficiency, ϵs) simply by direct reaction between elemental sulfur (S0) and ZVI in an aqueous suspension at ambient temperature. In comparison, the ϵs values obtained using Na2S, Na2S2O3, or Na2S2O4 as the sulfidation agents were only μ23, μ75, and μ38%, respectively. The sulfidated mZVI produced using the new method reacts with trichloroethylene (TCE) with very high rates and electron efficiencies: rate constants and electron efficiencies were 800- and 79-fold higher than those of the unsulfidated mZVI. The enhanced performance of this material, together with the operational advantages of S0 for sulfidation (including safety, stability, and cost), may make it a desirable product for full-scale engineering applications.
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U2 - 10.1021/acs.est.0c05397
DO - 10.1021/acs.est.0c05397
M3 - Article
C2 - 33302625
AN - SCOPUS:85098948803
SN - 0013-936X
VL - 55
SP - 645
EP - 654
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 1
ER -