IJUP08 - Universidade do Porto

Chromium remediation using zero valent iron - batch studies
G. Carvalho 1,2, Aurora Silva1, Cristina Delerue-Matos1 , A. Vega y Fuente2,3 and
António Fiúza 3
1 REQUIMTE, Instituto Superior de Engenharia do Instituto Politécnico do Porto
2Departamento de Geotecnia do Instituto Superior de Engenharia do Instituto Politécnico do Porto
3 CIGAR, Faculdade de Engenharia da Universidade do Porto
One of the main problems that modern societies are facing today, as a direct consequence
of their activities, is the change of the original conditions of the sites and their components
as result of human activities.
One of the group of substances that require special attention is heavy metals. They are
considered a priority problem due to its toxicity, and in certain cases, its carcinogenic
potential when in contact with populations or ecosystems. Chromium is one of the top
pollutants, because of their relative abundance as a contaminant, the dangerousness of their
ions, in particular Cr6+ and its high mobility in the environment. In fact, as it occurs in
anionic form it is not significantely sorbed by the soil.
This work aims to contribute for the knowledge of the geo-environmental phenomenon
associated to remediation of Cr6+ in contaminated water by using zero valent iron. The net
reactions of Cr6+ reduction whit zero valent iron and co precipitation of Cr3+ and Fe2+
are [1]:
In this work a low coast commercial iron was used to establish reaction kinetic parameters,
using batch test.
Solutions of Cr6+ were prepared with potassium dichromate. The method used to determine
the concentration of chromium present in samples was the colorimetric method [2].
Batch kinetic experiments were performed to evaluate the removal rate of Cr6+ in the
presence of iron under different operating parameters: temperature, concentration, pH, iron
mass.
These tests allowed to establish that reaction follows a first order kinetic. The kinetic
constants and the activation energy were estimated from the experimental data.
AKNOWLEDGMENS
The authors would like to thank Fundação para a Ciência e Tecnologia for the financial support of
the project POCI/ECM/59779/2004
References
[1] Biswajit Mukhopadhyay, Jon Sundquist, Rodney J. Schmitz, Removal of Cr(VI) Crcontaminated
groundwater through electrochemical addition of Fe(II) Journal of environmental
Management 82 (2002) 66-76.
[2] APHA Standard Methods for the Examination of Water and Wastewater 20th edition (1998),
Method 3500-Cr (D) - Colorimetric Method.
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