TY - JOUR
T1 - Anaerobic Dehalogenation by Reduced Aqueous Biochars
AU - Lokesh, Srinidhi
AU - Kim, Juhee
AU - Zhou, Yuwei
AU - Wu, Danping
AU - Pan, Bo
AU - Wang, Xilong
AU - Behrens, Sebastian
AU - Huang, Ching Hua
AU - Yang, Yu
N1 - Publisher Copyright:
© 2020 American Chemical Society. All rights reserved.
PY - 2020/12/1
Y1 - 2020/12/1
N2 - Dehalogenation is one of the most important reactions for eliminating trace organic pollutants in natural and engineering systems. This study investigated the dehalogenation of a model organohalogen compound, triclosan (TCS), by aqueous biochars (a-BCs) (<450 nm). We found that TCS can be anaerobically degraded by reduced a-BCs with a pseudo first-order degradation rate constant of 0.0011-0.011 h-1. The 288 h degradation fraction of TCS correlated significantly with the amount of a-BC-bound electrons (0.055 ± 0.00024 to 0.11 ± 0.0016 mol e-/mol C) available for donation after 24 h of pre-reduction by Shewanella putrefaciens CN32. Within the reduction period, the recovery of chlorine based on residual TCS and generated Cl- ranged from 73.6 to 85.2%, implying that a major fraction of TCS was fully dechlorinated, together with mass spectroscopic analysis of possible degradation byproducts. Least-squares numerical fitting, accounting for the reactions of hydroquinones/semiquinones in a-BCs with TCS and byproducts, can simulate the reaction kinetics well (R2 > 0.76) and suggest the first-step dechlorination as the rate-limiting step among the possible pathways. These results showcased that the reduced a-BCs can reductively degrade organohalogens with potential applications for wastewater treatment and groundwater remediation. While TCS was used as a model compound in this study, a-BC-based degradation can be likely applied to a range of redox-sensitive trace organic compounds.
AB - Dehalogenation is one of the most important reactions for eliminating trace organic pollutants in natural and engineering systems. This study investigated the dehalogenation of a model organohalogen compound, triclosan (TCS), by aqueous biochars (a-BCs) (<450 nm). We found that TCS can be anaerobically degraded by reduced a-BCs with a pseudo first-order degradation rate constant of 0.0011-0.011 h-1. The 288 h degradation fraction of TCS correlated significantly with the amount of a-BC-bound electrons (0.055 ± 0.00024 to 0.11 ± 0.0016 mol e-/mol C) available for donation after 24 h of pre-reduction by Shewanella putrefaciens CN32. Within the reduction period, the recovery of chlorine based on residual TCS and generated Cl- ranged from 73.6 to 85.2%, implying that a major fraction of TCS was fully dechlorinated, together with mass spectroscopic analysis of possible degradation byproducts. Least-squares numerical fitting, accounting for the reactions of hydroquinones/semiquinones in a-BCs with TCS and byproducts, can simulate the reaction kinetics well (R2 > 0.76) and suggest the first-step dechlorination as the rate-limiting step among the possible pathways. These results showcased that the reduced a-BCs can reductively degrade organohalogens with potential applications for wastewater treatment and groundwater remediation. While TCS was used as a model compound in this study, a-BC-based degradation can be likely applied to a range of redox-sensitive trace organic compounds.
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U2 - 10.1021/acs.est.0c05940
DO - 10.1021/acs.est.0c05940
M3 - Article
C2 - 33170651
AN - SCOPUS:85096620441
SN - 0013-936X
VL - 54
SP - 15142
EP - 15150
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 23
ER -