Remediation of trichloroethylene by microscale zero-valent iron aged under various groundwater conditions: Removal mechanism and physicochemical transformation

Fenglin Tang; Fangming Tian; Lin Zhang; Xiupei Yang; Jia Xin; Xilai Zheng

doi:10.1016/j.scitotenv.2021.145757

Remediation of trichloroethylene by microscale zero-valent iron aged under various groundwater conditions: Removal mechanism and physicochemical transformation

Sci Total Environ. 2021 Jun 25:775:145757. doi: 10.1016/j.scitotenv.2021.145757. Epub 2021 Feb 10.

Authors

Fenglin Tang¹, Fangming Tian², Lin Zhang², Xiupei Yang², Jia Xin³, Xilai Zheng⁴

Affiliations

¹ College of Chemistry and Chemical Engineering, Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong 637000, China; Key Lab of Marine Environmental Science and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
² College of Chemistry and Chemical Engineering, Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong 637000, China.
³ Key Lab of Marine Environmental Science and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China. Electronic address: xinj15@ouc.edu.cn.
⁴ Key Lab of Marine Environmental Science and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China. Electronic address: zhxilai@ouc.edu.cn.

PMID: 33611180
DOI: 10.1016/j.scitotenv.2021.145757

Abstract

Microscale zero-valent iron (mZVI) has been widely used for the in-situ groundwater remediation of various pollutants. However, the aging behavior of injected mZVI particles limits the widespread application in groundwater remediation projects. To assess the long-term reactivity of mZVI particles, the mechanism of trichloroethylene (TCE) degradation by various aged mZVI particles (A-mZVI) was determined by quantitatively evaluating the contributions of chemical reduction and adsorption. Further, this study investigated the physicochemical transformation of mZVI particles aged under various hydraulic conditions (static and dynamic), redox conditions (anoxic and aerobic) and aging durations (152 d and 455 d). The results show that the removal of TCE by different A-mZVI particles increased the sorption capacity in the initial period (0-6 h). However, in the long term, a significant inhibition of TCE removal was observed because of the decreased TCE reduction capacity caused by the hindrance of electron transfer, which was generated by corrosion precipitates. Furthermore, the characterization results demonstrated that despite the significant differences in the apparent morphology of the A-mZVI particles in various groundwater conditions, the final crystal corrosion products were mainly Fe₃O₄. Thus, the aging and inactivation of mZVI particles on TCE removal were promoted under the aerobic conditions. In addition, the structure of mZVI particles collapsed from the micro- to nanoscale under anaerobic dynamic over 455 d. No substantial impact on the final TCE removal was observed for the A-mZVI particles prepared under various hydraulic conditions and aging times. These findings provide insights regarding the impact mechanisms of corrosion precipitates on the removal of target contaminant and provide implications for long-term mZVI application under various target aquifer conditions.

Keywords: Aging effect; Microscale zero-valent iron; Removal mechanism; Transformation; Trichloroethylene (TCE).