TY - JOUR
T1 - Mechanism of carbon tetrachloride reduction in ferrous ion activated calcium peroxide system in the presence of methanol
AU - Tang, Ping
AU - Jiang, Wenchao
AU - Lyu, Shuguang
AU - Brusseau, Mark L.
AU - Xue, Yunfei
AU - Qiu, Zhaofu
AU - Sui, Qian
N1 - Publisher Copyright:
© 2019 Elsevier B.V.
PY - 2019/4/15
Y1 - 2019/4/15
N2 - This study investigated the reductive initiation for the depletion of highly oxidized/perhalogenated pollutants, specifically the degradation of carbon tetrachloride (CT) was induced by adding methanol (MeOH) into a ferrous ion (Fe(II)) activated calcium peroxide (CaO2) system. The results indicated that CT could be completely degraded within 20 min at CaO2/Fe(II)/MeOH/CT molar ratio of 30/40/10/1 in this system. Scavenging tests suggested that both superoxide radical anion (O2[rad]−) and carbon dioxide radical anion (CO2[rad]−) were predominant reactive species responsible for CT destruction. Hydroxymethyl radicals ([rad]CH2OH), an intermediate in the transformation of MeOH, could also initiate CT degradation by reducing C–Cl bond. GC/MS analysis identified CHCl3, C2Cl4, and C2Cl6 as the intermediates accompanied by CT destruction, and a reduction mechanism for CT degradation was proposed accordingly. In addition, the impact of solution matrix and initial solution pH were evaluated, and the results showed that Cl−, NO3−, and HCO3− had adverse effects on CT degradation. Moreover, the alkaline condition was unfavorable to CT depletion. In conclusion, the results obtained in the actual groundwater tests encouragingly demonstrated that the CaO2/Fe(II)/MeOH process is a highly promising technique for the remediation of CT-contaminated groundwater.
AB - This study investigated the reductive initiation for the depletion of highly oxidized/perhalogenated pollutants, specifically the degradation of carbon tetrachloride (CT) was induced by adding methanol (MeOH) into a ferrous ion (Fe(II)) activated calcium peroxide (CaO2) system. The results indicated that CT could be completely degraded within 20 min at CaO2/Fe(II)/MeOH/CT molar ratio of 30/40/10/1 in this system. Scavenging tests suggested that both superoxide radical anion (O2[rad]−) and carbon dioxide radical anion (CO2[rad]−) were predominant reactive species responsible for CT destruction. Hydroxymethyl radicals ([rad]CH2OH), an intermediate in the transformation of MeOH, could also initiate CT degradation by reducing C–Cl bond. GC/MS analysis identified CHCl3, C2Cl4, and C2Cl6 as the intermediates accompanied by CT destruction, and a reduction mechanism for CT degradation was proposed accordingly. In addition, the impact of solution matrix and initial solution pH were evaluated, and the results showed that Cl−, NO3−, and HCO3− had adverse effects on CT degradation. Moreover, the alkaline condition was unfavorable to CT depletion. In conclusion, the results obtained in the actual groundwater tests encouragingly demonstrated that the CaO2/Fe(II)/MeOH process is a highly promising technique for the remediation of CT-contaminated groundwater.
KW - Calcium peroxide
KW - Carbon tetrachloride
KW - Groundwater remediation
KW - Methanol
KW - Reductive radicals
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U2 - 10.1016/j.cej.2019.01.034
DO - 10.1016/j.cej.2019.01.034
M3 - Article
AN - SCOPUS:85059771610
SN - 1385-8947
VL - 362
SP - 243
EP - 250
JO - Chemical Engineering Journal
JF - Chemical Engineering Journal
ER -