Published Paper Details:

Heavy metal pollution in soil has become a major environmental issue across the world. It threatens the health of ecosystems, the productivity of farms, and the health of people. Cadmium (Cd), lead (Pb), and zinc (Zn) are three hazardous heavy metals that are especially bad because they stay in the environment for a long time, may build up in living things, and are found in many polluted areas. Chemical speciation, which is how metals are spread out among different geochemical forms, affects how easily they move through the environment, how available they are to living things, and how hazardous they might be. Total metal concentration is not enough to tell. Nano-zero-valent iron (nZVI) has garnered significant attention as a novel nanoremediation technique that may immobilize heavy metals via reduction, adsorption, and precipitation processes. This study paper investigates the efficacy of nZVI treatment in modifying the chemical speciation and diminishing the mobility of Cd, Pb, and Zn in contaminated soils. The core-shell structure of nZVI, which has a reactive zero-valent iron core and an iron oxide/hydroxide shell, gives it a unique dual role for cleaning up contaminants. Using successive extraction methods like the Tessier and BCR protocols, scientists may measure how metals move from mobile, bioavailable fractions (such exchangeable and acid-soluble) to more stable, residual fractions after nZVI therapy. Field and laboratory research show that using nZVI efficiently makes heavy metals less mobile by changing them into forms that are less bioavailable. However, how well it works depends on the soil's pH, organic matter content, moisture, nZVI dose, and weather circumstances. However, issues such as nanoparticle aggregation, quick oxidation, possible ecotoxicity, and cost-effectiveness compared to traditional iron-based remedies necessitate thorough evaluation. This thorough study brings together what we know about nZVI-mediated changes in chemical speciation, remediation mechanisms, evaluation methods, environmental effects, and future directions for sustainable soil remediation.