ENHANCED HEAVY METAL EXTRACTION FROM POST-MINING CONTAMINATED SOIL THROUGH IRON OXIDE NANOPARTICLE ADSORPTION AND SUBSEQUENT PHYTOREMEDIATION

Abstract

ABSTRACT. In the current paper, the iron oxide nanoparticles (IONPs) have been demonstrated to facilitate the extraction of heavy metals from post-mining contaminated soil due to their water solubility and adsorption capabilities for the target contaminants. Furthermore, IONPs were subsequently removed from the treated soil through phytoremediation and bioaccumulated in the roots and stems of legume plants. For that purpose, 20 nm IONPs coated with an organic shell of humic acid were engineered and their adsorption capacity was assessed to heavy metals as cadmium (Cd2+), lead (Pb2+), zinc (Zn2+), manganese (Mn2+), copper (Cu2+), and nickel (Ni2+), which are common pollutants of acid mine drainage. In the framework of phytoremediation employing legume plants, the IONPs were directly introduced into the experimental soil samples alongside compost. Subsequently, it was noted that the legume roots absorbed the nanoparticles, acting as carriers for the captured heavy metals, thus aiding in their translocation to the aboveground portions of the plants. When introduced into soil environments, humic acid-coated iron oxide nanoparticles in combination with compost may exert positive effects on rhizosphere microbial populations. This can occur through the reduction of toxic metal ion levels and the potential side reaction of degrading or transforming organic pollutants into less harmful substances. Ultimately, the heavy metals become immobilized within the plant biomass, which can subsequently be harvested and removed from the contaminated site. This process leads to soil purification and remediation. The report presented here outlines a promising avenue for practical implementation, combining organic-coated IONPs with select plants to enhance bioaccumulation of heavy metals. This approach aims to develop future cost-effective passive treatment systems for the phytoremediation of soils contaminated post-mining sites.

Keywords

• phytoremediation
• iron oxide nanoparticles
• post-mining contaminated soil