Development of iron oxide based sorbents for arsenic stabilization in contaminated soil

Abstract

High arsenic level in natural waters, and in the ground, is nowadays a worldwide problem. Soil stabilization is a low-cost technology aiming to reduce the arsenic mobility in soil preventing the migration of the contaminant into the environment. Addition of iron oxides to arsenic contaminated soils has been proposed as an effective remediation technique. The aim of the present work was to re-use iron ore broken pellets, i.e. a waste from mining industry, to immobilize arsenic within soil. A treatment was developed to increase the surface area of the iron ore broken pellets and therefore increasing its adsorption efficiency. Four different iron oxides were evaluates: metallic iron grid, fine magnetite powder, iron ore broken pellets and broken pellets modified by the developed treatment. Spherical nanoparticle aggregates covering the surface of the broken pellets were observed upon the application of the developed treatment. The immobilization performance of the iron oxide materials was evaluates for soil with and without plants. Soil pore water samples were collected and analysed after 11, 30 and 54 days. At the end of the experiment, the trace-element content of the plant shoots was analysed and a sequential extraction was performed for bulk and rhizosphere samples. While the zerovalent iron significantly reduced the mobility of arsenic in the contaminates soil, both in the presence and absence of plants, the other three iron oxide amendments did not significantly reduced the mobility of arsenic in the soil.