Yankuang ceshi (Sep 2018)

Simultaneous Removal of TCE and Cr(Ⅵ) in Groundwater by Using Bentonite-supported Nanoscale Fe/Ni

  • DENG Ri-xin,
  • LUO Wei-jia,
  • HAN Yi-tong,
  • LI Zhi-xiong,
  • CHEN Jia-wei

DOI
https://doi.org/10.15898/j.cnki.11-2131/td.201801280013
Journal volume & issue
Vol. 37, no. 5
pp. 541 – 548

Abstract

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BACKGROUND The injection of nanoscale zero valent iron particles (nZVI) into groundwater has been recently developed as an in-situ groundwater remediation technology. Most researches focused on how to remove a single type pollutant and the related mechanism. However, cases on the coexisting multiple pollutants in groundwater should not be ignored. OBJECTIVES To synthesize the bentonite-supported nanoscale Fe/Ni bimetals(B-Fe/Ni), in order to remove typical pollutants of trichloroethylene (TCE) and hexavalent chromium[Cr(Ⅵ)] which exhibit high reactivity and are more stable to remediate contaminated water. Also, to assess the performance of B-Fe/Ni on the removal of coexisting TCE and Cr(Ⅵ) and to determine the reaction mechanism. METHODS B-Fe/Ni was synthesized by one-step method and the batch experiments were conducted on the removal of TCE coexisted with different concentration of Cr(Ⅵ) by B-Fe/Ni. The samples of B-Fe/Ni were characterized before and after the reaction, and the contents of TCE and Cr(Ⅵ) were also monitored. RESULTS B-Fe/Ni can efficiently remediate Cr(Ⅵ) and TCE in water. B-Fe/Ni (1 g/L) could completely remove Cr(Ⅵ) (50 mg/L) in 2 h in the presence of coexisting TCE (0.1 mmol/L). However, the degradation rate of TCE by B-Fe/Ni was decreased with increased initial concentration of Cr(Ⅵ) (0, 10, 30, 50 mg/L). According to TEM-EDS and XPS for B-Fe/Ni before and after reaction, it is shown that Fe-Cr co-precipitation from the fast interaction of B-Fe/Ni with Cr(Ⅵ) occupied the reactive sites on the surface of B-Fe/Ni, mitigating the degradation of TCE. According to the final products of TCE degradation, it is shown that TCE was completely dechlorinated. CONCLUSIONS B-Fe/Ni is suitable for the remediation of groundwater combined pollution. In practical applications, it is necessary to consider the mutual influence of multiple pollutants and select the appropriate reagent dosage and injection method. The proposed method has important theoretical significance and application for the development of ZVI repair technology.

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