Iron Based Immobilization for Metal Contaminated Soils

Abstract

Remediation of contaminated soils is an important task which aims to reduce the impact of toxic metalloids such as Cd, Cu and As on public health. In-situ immobilization via the addition of soil amendments such as iron-based materials reduces the mobility and transport of these toxic metalloids in the environment. A wide range of iron-based materials have been used for metal immobilization in contaminated soils including iron oxides, zerovalent iron, nano-zerovalent iron (nZVI), iron salts, green synthesized iron oxide nanoparticle (GION) or phytogenic iron oxides nanoparticles (PION), Fe-Al layered double hydroxide and CMC (carboxymethylcellulose) based iron. The reactivity and surface area of zerovalent iron is increased at the nanoscale when utilized as nZVI thereby increasing its effectiveness as demonstrated by previous studies. The efficiency of nZVI in remediation of contaminated soils is limited by the strong tendency of its particles to agglomerate. In order to overcome this limitation and facilitate the delivery and mobility of nZVI in soils, nZVI is immobilized onto a carrier such as resin, potato starch, zeolite, or mesoporous silica or by increasing colloidal stability with the addition of other soil amendments. Even though, there is g rowing concern over the environmental impact of nanoparticles, the use of plant extracts to synthesize iron nanoparticles is environmentally friendly and economical.