Zero-Valent Iron Nanoparticles Remediate Nickel-Contaminated Aqueous Solutions and Biosolids-Amended Agricultural Soil.

Ahmed M Mahdy,Tiequan Zhang,Nieven O Fathi,Zhi-Qing Lin,Rasha M Badr Eldin

doi:10.3390/ma14102655

Abstract

Nickel (Ni+2) accumulation in wastewater treatment sludge poses a potential environmental risk with biosolids-land application. An incubation experiment was conducted to evaluate the effect of nanoparticles of zero-valent iron (nZVI) on Ni+2 sorption in biosolids-treated agricultural soils. Two application rates of biosolids (0, 5%, w/w) and four treatment levels (0, 1, 5, and 10 g/kg) of nZVI were examined, either separately or interactively. The results of this study showed significant differences in Ni+2 sorption capacity between different nZVI treatments. The initial Ni+2 concentration in biosolids-amended soil significantly affected Ni sorption in the soil treated with nZVI. The “H-shape” of sorption isotherm in nZVI-treated soil reflects strong interaction between the Ni concentration and the nZVI treatment, while the C-shape of sorption isotherm in biosolids-amended soil without the nZVI treatment indicates intermediate affinity for Ni+2 sorption. Nickel retention in soil was increased with the increase of nZVI levels. The removal efficiency of Ni+2 by nZVI from solution was increased with the increase of pH from 5 to 11 and reached a maximum of 99.56% at pH 11 and nZVI treatment of 10 g/kg. The Ni+2 desorption rate decreased from 92 to 7, 4, and 1% with increasing nZVI treatment levels from 0 to 1, 5, and 10 g/kg, respectively, with a soil Ni+2 concentration of 50 mg/L. The maximum adsorption capacity (𝑞max) of 10 g/kg nZVI-treated soil was 333.3 mg/g, which was much higher than those from the other treatments of 0 (5 mg/g), 1 (25 mg/g), and 5 g/kg (125 mg/g). The underlying mechanism for Ni+2 immobilization using nZVI in an aquatic environment is controlled by a sorption process, reduction of metal ion to zero-valent metal, as well as (co)precipitation. Moreover, increasing the nZVI treatment level in biosolids-amended soil significantly decreased bioavailable Ni+2 concentrations in the soil.

Highlights

Soil contamination with heavy metals, such as nickel, is a significant and global problem [1]
The morphology of nanoscale zero-valent iron (nZVI) particles was analyzed by scanning electron microscopy (SEM) detection, and the results clearly showed that the representative single particle size dimension lies in the range 1–100 nm, the nZVI particles are spherical with an average size of 42–45 nm, and the particles are uniformly distributed
These results are in accordance with sorbent for the(Figure removal ofTherefore, Ni+2 respectively this study demonstrated that nZVI

Summary

Introduction

Soil contamination with heavy metals, such as nickel, is a significant and global problem [1]. Anthropogenic activities, such as mining, tanning, textile, metallurgical [2], and electroplating processes, have resulted in severe soil and water nickel contamination. The land application of biosolids may result in toxic Ni+2 contamination in biosolids-amended agricultural soil and in land surface runoff. In situ remediation of Ni+2 -contaminated soil and water can be achieved through different physical, chemical, and biological processes. Ni2+ can be removed from contaminated soils and waters by chemical adsorption and precipitation using nanoscale zero-valent iron (nZVI) [3,4,5]. Nanoscale particles of

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