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Enhanced reductive degradation of carbon tetrachloride by carbon dioxide radical anion-based sodium percarbonate/Fe(II)/formic acid system in aqueous solution

Jiang, Wenchao, Tang, Ping, Lu, Shuguang, Zhang, Xiang, Qiu, Zhaofu, Sui, Qian
Frontiers of environmental science & engineering 2018 v.12 no.2 pp. 6
aqueous solutions, bicarbonates, carbon dioxide, carbon tetrachloride, chlorides, formic acid, groundwater contamination, iron, mineralization, pH, reactive oxygen species, remediation, sodium percarbonate
The performance of sodium percarbonate (SPC) activated with ferrous ion (Fe(II)) with the addition of formic acid (FA) to stimulate the degradation of carbon tetrachloride (CT) was investigated. Results showed that CTcould be entirely reduced within 15 min in the system at a variety of SPC/Fe(II)/FA/CT molar ratios in experimental level. Scavenging tests indicated that carbon dioxide radical anion (CO₂∙–) was the dominant reactive oxygen species responsible for CT degradation. CT degradation rate, to a large extent, increased with increasing dosages of chemical agents and the optimal molar ratio of SPC/Fe(II)/FA/CT was set as 60/60/60/1. The initial concentration of CT can hardly affect the CT removal, while CT degradation was favorable in the pH range of 3.0–9.0, but apparently inhibited at pH 12. Cl– and HCO ₃⁻ of high concentration showed negative impact on CT removal. Cl– released from CTwas detected and the results confirmed nearly complete mineralization of CT. CT degradation was proposed by reductive C-Cl bond splitting. This study demonstrated that SPC activated with Fe(II) with the addition of FA may be promising technique for CT remediation in contaminated groundwater.