Iron nanoparticles for Cr(VI) removal from contaminated soil

Heavy metals and metalloids contamination of soils is caused by the rapidly expanding industrial areas, mine tailings, land application of fertilizers, animal manures, sewage sludge, pesticides, wastewater, irrigation, coal combustion residues, spillage of petrochemicals, and atmospheric deposition. The most common heavy metals found in polluted soils are lead (Pb), zinc (Zn), cadmium (Cd), nickel (Ni), and chromium (Cr). This chapter discusses the occurrence and characteristics of Cr in soil. Hexavalent Cr is a strong oxidizing agent, and it exists in the environment as an oxyanion: chromate (CrO42-), dichromate (Cr2O72-), hydrogen chromate (HCrO4-), or dihydrogen chromate (H2CrO4). The effectiveness of nanoscale zero-valent iron (nZVI) toward hexavalent chromium Cr(VI) reduction has been widely demonstrated by several studies in the literature. Several studies in the recent years have been carried out aiming at demonstrating the effectiveness of nZVI in soil remediation. Most of them were performed in spiked soil, and additional studies are required before implementing this technology on full scale.