Reducing mobility of arsenic in a brownfield soil using
stabilized zero-valent iron nanoparticles
M. Gil-Díaz1*, J. Alonso1, E. Rodríguez-Valdés2, M.C. Lobo1
1
IMIDRA, Finca “El Encín” A-2, Km 38,2. 28800 Alcalá de Henares (Madrid) Spain.
2
Universidad de Oviedo, Mieres 33600 (Asturias) Spain
* Presenting author contact: mar.gil.diaz@madrid.org
Arsenic is a trace element which is naturally found in the environment, but
anthropogenic activities (e.g. mining, industrial wastes, application of agricultural
pesticides, and military activities), have increased its concentration in soils and
groundwater. It is one of the most toxic contaminants. Arsenic speciation in soils is
complex, including organic forms and inorganic species, arsenate (As(V)) and arsenite
(As(III)), which are the most abundant. The availability of As in soils is usually driven by
many factors, such as pH, Fe-oxides, phosphorus, (co)precipitation in salts, organic
matter, clays, rainfall, etc.
In recent years, nanoscaled zero-valent iron (nZVI) has been tested to remediated both
organic and inorganic pollutants in soil and groundwater, and has received increasing
amounts of attention due to its potential for broader application, higher reactivity, and
cost-effectiveness. Much of the research has been conducted with artificially
contaminated soils. In the present study a highly As-contaminated soil from a
brownfield was employed. The main objective of this research was to evaluate the
effectiveness of nZVI for reducing the availability and leachability of As in this soil.
Soil from a brownfield site was treated with commercial nZVI suspension (NANOFER
25S, NANO IRON, Rajhrad, Czech Republic) at doses 1 and 10%. The availability of
As in the soil was evaluated after a sequential extraction procedure developed by
Tessier et al. (1979). To quantify As leachability in soil, TCLP (toxicity characteristic
leaching procedure) tests were performed following EPA Method 1311 at various
contact times (1, 3, 24 and 48 h). The phytotoxicity of soil before and after nZVI
treatment was evaluated as germination index according to the standard method of
Zucconi et al. (1981).
Results from the sequential extraction procedure showed a significant reduction of As
in more available fractions after treatment with nZVI. The As leachability also
dramatically decreased after nanoparticle application regardless the contact time.
Germination tests showed a high phytotoxicity of the brownfield soil which was reduced
to moderate toxicity when soils were treated with nZVI. Zero-valent iron nanoparticles
has been shown effective for immobilizing As, and, consequently, for minimizing the
brownfield toxicity. This study provides evidences that the stabilized ZVI nanoparticles
may offer an useful alternative for in situ remediation of As-contaminated soils, more
cost-effective and environmentally friendly than other in situ methods.
Tessier A, Campbell P.G.C., Bisson M. 1979. Anal. Chem. 51, 844-850.
Zucconi, F., A. Pera, and M. Forte. 1981. BioCycle, 2, 54-57.
Acknowledgements. This work has been supported by Project CTM 2010-20617-C0202 and EIADES PROGRAM S2009/AMB-1478.