Zhouwei Miao,Xiaogang Gu,Shuguang Lu,Dionysios D. Dionysiou,Souhail R. Al-Abed,Xueke Zang,Xiaoliang Wu,Zhaofu Qiu,Qian Sui,Muhammad Danish
The performance of chelated Fe(II)-based catalyzed sodium percarbonate (SPC) stimulating the degradation of perchloroethylene (PCE) in aqueous solution was investigated using six different chelating agents (CA), namely, citric acid monohydrate (CIT), oxalic acid (OA), l -ascorbic acid (ASC), ethylenediaminetetraacetic acid (EDTA), trisodium citrate 2-hydrate (CIT-Na 3 ), and EDTA-Na 2 , at CA/Fe(II)/SPC/PCE molar ratios of 2/4/4/1, 4/4/4/1 and 8/4/4/1. The results indicated that the addition of CIT and OA significantly enhanced the PCE degradation. In addition, investigations using free radical probe compounds and radical scavengers revealed that PCE was primarily degraded by HO radical oxidation in Fe(II)/SPC, CIT/Fe(II)/SPC, and OA/Fe(II)/SPC systems and O 2 − also participated in the degradation of PCE in CIT/Fe(II)/SPC and OA/Fe(II)/SPC systems. The intensity of HO detected by electron paramagnetic resonance (EPR) in CIT/Fe(II)/SPC and OA/Fe(II)/SPC systems indicated that the addition of CIT or OA indeed enhanced the continuous production of HO and enabled the intensity of HO to be more stable. The results demonstrated that CIT and OA significantly improved the PCE degradation efficiency by increasing the concentration of Fe(II) and maintaining the concentration of HO radicals in solution. In conclusion, chelated Fe(II)-based catalyzed SPC oxidation process shows enormous practical prospects for the remediation of PCE-contaminated groundwater because of the effectiveness without pre-adjusting the solution pH and complete mineralization in Fe(II)/SPC, CIT/Fe(II)/SPC and OA/Fe(II)/SPC systems.
In this study, the application of sodium percarbonate (SPC) catalyzed by various chelated-Fe(II) to stimulate the degradation of benzene in groundwater remediation was investigated. Effective oxidation of benzene was achieved in CIT/SPC/Fe(II) and OA/SPC/Fe(II) systems. The reaction mechanism for benzene degradation in CIT/SPC/Fe(II) and OA/SPC/Fe(II) systems was elucidated by free radical probe compound tests, free radical scavenger tests and electron paramagnetic resonance (EPR) analysis. And hydroxyl radical (HO ) and superoxide anion radical ( O 2 - ) were confirmed as the predominant species responsible for benzene degradation. Besides, the effects of various factors, such as the solution characteristics including the presence of anions (Cl − , HCO 3 − , SO 4 2− and NO 3 − ), natural organic materials (NOM), and the initial solution pH on benzene degradation were also evaluated. The influences caused by SO 4 2− , NO 3 − , Cl − and NOM were negligible, but HCO 3 − anion had a slightly inhibitive effect in low concentration (1 mM) and an apparently inhibitive effect in high concentration (10–100 mM). However, the additions of CIT and OA eliminated the adverse influence of HCO 3 − and ensured a high benzene degradation efficiency at wider pH range. Finally, results obtained in actual groundwater test strongly demonstrated that Fe(II)-CIT and Fe(II)-OA catalyzed SPC systems are applicable for the remediation of benzene-contaminated groundwater in practice.
危险品化学品经营许可证（带存储）