Application of Nanotechnology in Remediation of Heavy Metals Polluted Soils

Abstract

Nanotechnology offers a number of highly efficient and less costly techniques that could work to immobilize contaminants. Nano-particles; nano scale zero valent iron “nZVI”, nZVI-bentonite, nanoalginite, and nano carbon; are used as a potential sorbents to immobilize Cd and Pb in polluted soils. These nano-particles are prepared in lab either using top-down or bottom-up methods, then characterized using transmission electron microscope (TEM). The prepared nano-particles proved to have very small size (less than 70 nm), high surface area (194.2-259.7 m²/g) and cation exchange capacity (42.5-47.7 Cmolc/kg). Also, the prepared nano-particles proved high adsorption capacity for Pb and Cd, and high retention for the adsorbate metal. The maximum adsorption capacity of nano-particles ranged from 37450-93450 and 17850-25970 mg kg^-1 for Pb and Cd, respectively. Moreover, except for nano carbon, only small quantities represent 10.8-33.4% and 13.7-35.6% of the previously adsorbed Cd and Pb, respectively, were desorbed. The tested nano particles proved high efficiency in immobilizing Cd and Pb in polluted soils. The plant available Pb and Cd as extracted using DTPA extract in polluted soils treated with nano particles decreased to levels lower than those (0.06 and 2.88 mg/kg, for Cd and Pb, respectively) reported for non-polluted soils of Egypt.