Abstract
The aggregation of nanoscale zero-valent iron (nZVI) particles and their limited transport ability in environmental media hinder their application in environmental remediation. In this study, the Cr(VI) removal efficiency, transport performance, and toxicity of nZVI and bentonite-modified nZVI (B-nZVI) were investigated. Compared with nZVI, B-nZVI improved the removal efficiency of Cr(VI) by 10%, and also significantly increased the transport in quartz sand and soil. Increasing the flow rate can enhance the transport of nZVI and B-nZVI in the quartz sand columns. The transport of the two materials in different soils was negatively correlated with the clay composition. Besides, modification of nZVI by bentonite could reduce toxicity to luminous bacteria (Photobacterium phosphereum T3) and ryegrass (Lolium perenne L.). Compared with Fe-EDTA, the transfer factors of nZVI and B-nZVI were 65.0% and 66.4% lower, respectively. This indicated that although iron nanoparticles accumulated in the roots of ryegrass, they were difficult to be transported to the shoots. The results of this study indicate that B-nZVI has a strong application potential in in situ environmental remediation.
Highlights
Nanoscale zerovalent iron is an engineered nanoparticle that is increasingly used in environmental remediation [1,2]
The morphology and size of the newly prepared Nanoscale zerovalent iron (nZVI) and bentonite-modified nZVI (B-nZVI) were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM)
The SEM images showed that nZVI were basically spherical and aggregated in a chain-like structure, which can be mainly caused by the magnetic properties of the materials [42]
Summary
Nanoscale zerovalent iron (nZVI) is an engineered nanoparticle that is increasingly used in environmental remediation [1,2]. Due to its large specific surface area, strong adsorption, and reactivity to pollutants, nZVI has been reported to have a high removal efficiency on heavy metals, halogenated hydrocarbons, and other pollutants [3,4,5,6,7,8]. NZVI showed great performance in the remediation of groundwater contaminated with hexavalent chromium [9]. The removal efficiency of pollutants is determined by a range of properties, including aggregation potential, particle surface properties, particle mobility, and chemical reactivity, and the characteristics of pollutants [10]. NZVI can react with oxygen and/or water to form iron oxides layer on the particle surface, which prevents the further contact with pollutants [11]
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