TY - JOUR

T1 - Fast degradation of vinyl chloride by green rust and nitrogen-doped graphene

AU - Ouyang, Qiong

AU - Tobler, Dominique J.

AU - Deng, Jia

AU - Huang, Lizhi

AU - Jakobsen, Rasmus

AU - Hansen, Hans Chr B.

N1 - Funding Information: The authors thank lab technicians Anita Schj\u00F8dt Sandager and Birgitte Boje Rasmussen for help and support with GC and C/N analysis. The authors further acknowledge financial support from the Guangzhou Elite Project (Qiong Ouyang), project 9067-0040B (\u201CGreenCat\u201D, funded by Innovation Fund Denmark , Hans Christian Bruun Hansen and Dominique J. Tobler) and the National Natural Science Foundation of China (Grant No. 52270165 , 51978537 , and 41807188 , Lizhi Huang and Jia Deng).

PY - 2024

Y1 - 2024

N2 - Carbonaceous materials catalyze reductive dechlorination of chlorinated ethylenes (CEs) by iron(II) materials providing a new approach for the remediation of CE polluted groundwater. While most CEs are reduced via β-elimination, vinyl chloride (VC), the most toxic and recalcitrant CE, degrades by hydrogenolysis. The significance of carbon catalysts for reduction of VC is well documented for iron(0) systems, but hardly investigated with iron(II) materials as reductants. In this study, a layered iron(II)‑iron(III) hydroxide sulfate (green rust) was used as reductant for VC, with an N-doped graphene (NG), prepared by co-pyrolysis of graphene and urea, as catalyst. VC (80 μM) was completely reduced to ethylene within 336 h in the presence of 5 g Fe/L GR and 5 g/L NG pyrolyzed at 950 °C, following pseudo-first-order kinetics with a rate constant of 0.017 h−1. Dosing experiments demonstrated that dechlorination of VC takes place on the NG phase. Monitoring of hydrogen formation, cyclic voltammetry, and quenching experiments demonstrated that atomic hydrogen contributes significantly to the dehalogenation reaction, where NG is critical for formation of atomic hydrogen. CE competition experiments demonstrated the presence of specific VC reduction sites with hydrogenolysis being unaffected by concurrent β-elimination reactions. The system exhibited excellent performance in natural groundwaters and in comparison with iron(0) systems. This study demonstrates that GR + NG is a promising system for remediation of VC contaminated groundwater, and the mechanistic part of the study can be used as a reference for subsequent studies.

AB - Carbonaceous materials catalyze reductive dechlorination of chlorinated ethylenes (CEs) by iron(II) materials providing a new approach for the remediation of CE polluted groundwater. While most CEs are reduced via β-elimination, vinyl chloride (VC), the most toxic and recalcitrant CE, degrades by hydrogenolysis. The significance of carbon catalysts for reduction of VC is well documented for iron(0) systems, but hardly investigated with iron(II) materials as reductants. In this study, a layered iron(II)‑iron(III) hydroxide sulfate (green rust) was used as reductant for VC, with an N-doped graphene (NG), prepared by co-pyrolysis of graphene and urea, as catalyst. VC (80 μM) was completely reduced to ethylene within 336 h in the presence of 5 g Fe/L GR and 5 g/L NG pyrolyzed at 950 °C, following pseudo-first-order kinetics with a rate constant of 0.017 h−1. Dosing experiments demonstrated that dechlorination of VC takes place on the NG phase. Monitoring of hydrogen formation, cyclic voltammetry, and quenching experiments demonstrated that atomic hydrogen contributes significantly to the dehalogenation reaction, where NG is critical for formation of atomic hydrogen. CE competition experiments demonstrated the presence of specific VC reduction sites with hydrogenolysis being unaffected by concurrent β-elimination reactions. The system exhibited excellent performance in natural groundwaters and in comparison with iron(0) systems. This study demonstrates that GR + NG is a promising system for remediation of VC contaminated groundwater, and the mechanistic part of the study can be used as a reference for subsequent studies.

KW - Catalysis

KW - Chlorinated ethylenes

KW - Dechlorination

KW - Electron transfer

KW - Hydrogen production

KW - Iron(II) hydroxide

U2 - 10.1016/j.scitotenv.2024.172825

DO - 10.1016/j.scitotenv.2024.172825

M3 - Journal article

C2 - 38692311

AN - SCOPUS:85192241400

VL - 931

JO - Science of the Total Environment

JF - Science of the Total Environment

SN - 0048-9697

M1 - 172825

ER -