Simultaneous stabilization of Pb and improvement of soil strength using nZVI

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.

Remediation of Cr(VI)-Contaminated Soil by Nano-Zero-Valent Iron in Combination with Biochar or Humic Acid and the Consequences for Plant Performance

“…Recently, nanoremediation based on nano zero-valent iron (nZVI) has attracted increasing attention due to its environmental friendliness, high efficiency, and wide applications [9]. nZVI has been used to reduce leaching of toxic metals through adsorption, complexation and chemical reduction processes [10][11][12][13][14][15][16]. Numerous studies have reported applications of nZVI in the remediation of soils contaminated with Cr [17][18][19][20] as well as other toxic metals [14][15][16] and organic contaminants [21].…”

Preparation of Biomass Activated Carbon Supported Nanoscale Zero-Valent Iron (Nzvi) and Its Application in Decolorization of Methyl Orange from Aqueous Solution

“…Under the action of dispersant, iron particles were difficult to agglomerate and oxidize. The electrolytic process occurs at the cathode and anode as follows [25]: Anode:…”

Morphological and mineral features of nZVI-induced precipitation on quartz particles

“…Our previous study has demonstrated that the corrosion of nZVI and its induced precipitation is essentially evidence of the mass transfer from nZVI to the soil particles that responsible for the changes of physicochemical of soil and the improvement of soil's geotechnical strength (Zhou et al, 2018). However, soil particles composed predominantly of various minerals, organics, ions, and microorganisms etc.…”