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Sci Total Environ. 2019 Feb 15;651(Pt 1):877-884. doi: 10.1016/j.scitotenv.2018.09.146. Epub 2018 Sep 12.

Simultaneous stabilization of Pb and improvement of soil strength using nZVI.

Author information

1
Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China.
2
School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau, China; Shenzhen Key Laboratory of Soil and Groundwater Pollution Control, Shenzhen, China.
3
School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Shenzhen Key Laboratory of Soil and Groundwater Pollution Control, Shenzhen, China. Electronic address: yisp@sustc.edu.cn.
4
Geotechnical Engineering School of Engineering, The University of Warwick, Coventry, UK.
5
School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Shenzhen Key Laboratory of Soil and Groundwater Pollution Control, Shenzhen, China.

Abstract

This study demonstrates the feasibility of nanoscale Zero-Valent Iron (nZVI) for simultaneous stabilization of Pb and improvement of soil strength via batch experiments. The soil samples were prepared using slurry and pre-consolidation method at nZVI doses of 0.2%, 1%, 5%, and 10% (by dry weight). The physicochemical and geotechnical properties of Pb-contaminated soil treated by nZVI were analyzed. The results indicate that the contamination of Pb(II) resulted in a notable reduction in the undrained shear strength of soil from 16.85 kPa to 7.25 kPa. As expected, the Pb in exchangeable and carbonate-bound fractions decreased significantly with the increasing doses of nZVI. Meanwhile, the undrained shear strength of Pb-contaminated soil enhanced substantially as the increase of nZVI, from 25.83 kPa (0.2% nZVI treatment) to 69.33 kPa (10% nZVI treatment). An abundance of bubbles, generated from the oxidation of nZVI, was recorded. The mechanisms for simultaneous stabilization of Pb and soil improvement primarily include: 1) the precipitation and transformation of Pb-/Fe-hydrated oxides on the soil particles and their induced bounding effects; 2) the increased drainage capability of soil as the occupation of nZVI aggregates and bubbles in the macropores space and 3) the lower soil density derived from the increase in microbubbles retained in the soil. This study is provided to facilitate the application of nZVI in the redevelopment of contaminated soil.

KEYWORDS:

Lead, contaminated soil; Physicochemical property; Undrained shear strength; nZVI

PMID:
30257228
DOI:
10.1016/j.scitotenv.2018.09.146
[Indexed for MEDLINE]

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