TY - JOUR
T1 - Enhanced redox degradation of chlorinated hydrocarbons by the Fe(II)-catalyzed calcium peroxide system in the presence of formic acid and citric acid
AU - Jiang, Wenchao
AU - Tang, Ping
AU - Lyu, Shuguang
AU - Brusseau, Mark L.
AU - Xue, Yunfei
AU - Zhang, Xiang
AU - Qiu, Zhaofu
AU - Sui, Qian
N1 - Funding Information:
This study was financially supported by a grant from the International Academic Cooperation and Exchange Program of Shanghai Science and Technology Committee ( 18230722700 ) and the contribution of Mark L. Brusseau were supported by the NIEHS Superfund Research Program of the United States ( PS 42 ES04940 ). We thank the reviewers for their constructive comments.
Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2019/4/15
Y1 - 2019/4/15
N2 - Two carboxylic acids (formic acid (FA) and citric acid (CIT)) enhanced the Fenton process using Fe(II)-activated calcium peroxide (CP) to develop a hydroxyl (HO[rad]) and carbon dioxide radical (CO2[rad]−) coexistence process for the simultaneous redox-based degradation of three chlorinated hydrocarbons (CHs), namely carbon tetrachloride (CT), tetrachloroethene (PCE), and trichloroethene (TCE), was investigated. The experimental results showed that CT removal was increased while PCE and TCE degradation were decreased with the addition of FA to the Fe(II)/CP system. However, addition of CIT to the Fe(II)/CP/FA system enhanced the removal efficiency of all three contaminants. For example, 81.7%, 79.4%, and 96.1% of CT, PCE, and TCE, respectively, were removed simultaneously under the optimal molar ratio of 12/12/12/12/1 of CIT/CP/Fe(II)/FA/CHs. Mechanism study confirmed the specific roles of HO[rad] and secondarily generated CO2[rad]− radical. PCE and TCE were degraded oxidatively by HO[rad] while CT was degraded via reductive dechlorination by CO2[rad]−. Carbonate reduced PCE and TCE degradation in actual groundwater as it consumed reactive oxygen species, whereas humic acid and neutral pH had minimal impact on contaminant removal. These results can help us better understand the synergistic effects of carboxylic acids in the modified Fenton process for the redox degradation of refractory chlorinated hydrocarbons.
AB - Two carboxylic acids (formic acid (FA) and citric acid (CIT)) enhanced the Fenton process using Fe(II)-activated calcium peroxide (CP) to develop a hydroxyl (HO[rad]) and carbon dioxide radical (CO2[rad]−) coexistence process for the simultaneous redox-based degradation of three chlorinated hydrocarbons (CHs), namely carbon tetrachloride (CT), tetrachloroethene (PCE), and trichloroethene (TCE), was investigated. The experimental results showed that CT removal was increased while PCE and TCE degradation were decreased with the addition of FA to the Fe(II)/CP system. However, addition of CIT to the Fe(II)/CP/FA system enhanced the removal efficiency of all three contaminants. For example, 81.7%, 79.4%, and 96.1% of CT, PCE, and TCE, respectively, were removed simultaneously under the optimal molar ratio of 12/12/12/12/1 of CIT/CP/Fe(II)/FA/CHs. Mechanism study confirmed the specific roles of HO[rad] and secondarily generated CO2[rad]− radical. PCE and TCE were degraded oxidatively by HO[rad] while CT was degraded via reductive dechlorination by CO2[rad]−. Carbonate reduced PCE and TCE degradation in actual groundwater as it consumed reactive oxygen species, whereas humic acid and neutral pH had minimal impact on contaminant removal. These results can help us better understand the synergistic effects of carboxylic acids in the modified Fenton process for the redox degradation of refractory chlorinated hydrocarbons.
KW - Calcium peroxide
KW - Citric acid
KW - Formic acid
KW - Groundwater remediation
KW - Selective redox degradation
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U2 - 10.1016/j.jhazmat.2019.01.057
DO - 10.1016/j.jhazmat.2019.01.057
M3 - Article
C2 - 30710779
AN - SCOPUS:85060670723
SN - 0304-3894
VL - 368
SP - 506
EP - 513
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
ER -