Solusionario-Bird

Physics and Chemistry of the Earth xxx (2011) xxx–xxx

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Physics and Chemistry of the Earth
journal homepage: www.elsevier.com/locate/pce

Removal of As, Cd, Cu, Ni, Pb, and Zn from a highly contaminated industrial soil using surfactant enhanced soil washing
Luis G. Torres a,⇑, Rosario B. Lopez a, Margarita Beltran b
a b

Unidad ProfesionalInterdisciplinaria de Biotecnología, Instituto Politécnico Nacional, Av. Acueducto s.n., Col. Barrio la Laguna Ticoman, 07340 Mexico, DF, Mexico Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Av. San Pablo 180, 02200 Mexico, DF, Mexico

a r t i c l e

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a b s t r a c t
Surfactant enhanced soil washing (SESW) was applied to an industrial contaminated soil. A preliminarycharacterization of the soil regarding the alkaline-earth metals, Na, K, Ca and Mg took values of 2866, 2036, 2783 and 4149 mg/kg. The heavy metals As, Cd, Cu, Pb, Ni and Zn, had values of 4019, 14, 35582, 70, 2603, and 261 mg/kg, respectively. When using different surfactants, high removal of Cu, Ni and Zn were found, and medium removals for Pb, As and Cd. In the case of these three metals, tap waterremoved more than the surfactant solutions, except for the case of As. There were surfactants with average removals (this is, the removal for all the metals studied) of 67.1% (Tween 80), 64.9% (Surfacpol 14104) and 61.2% (Emulgin W600). There were exceptional removals using Texapon N-40 (83.2%, 82.8% and 86.6% for Cu, Ni and Zn), Tween 80 (85.9, 85.4 and 81.5 for Cd, Zn and Cu), Polafix CAPB (79%,83.2% and 49.7% for Ni, Zn and As). The worst results were obtained with POLAFIX LO with a global removal of 45%, well below of the average removal with tap water (50.2%).All removal efficiencies are reported for a one step washing using 0.5% surfactant solutions, except for the case of mezquite gum, where a 0.1% solution was employed. Ó 2011 Elsevier Ltd. All rights reserved.

Article history:Received 14 July 2010 Received in revised form 5 January 2011 Accepted 4 February 2011 Available online xxxx Keywords: Industrial soil Metals Soil washing Surfactants

1. Introduction Soil contamination by metals has both non-anthropogenic and anthropogenic sources. Regarding the last, it has been reported that many mankind activities can lead to contamination of soils with different metals.Industrial activities are very frequently the main source of this kind of contamination. On the other hand, metals can be put in contact with soils during extraction of metal-rich minerals. The indiscriminated use of certain pesticides and fertilizers could lead also in metal contamination in the fields. Burning of fuels with high metals content and the subsequent precipitation of metals is another sourceof metals contamination. Also, metallurgical industries, surface treatment industries, sewage sludge amendment are other sources of metal contamination. Many methods have been suggested to eliminate metals from soils. Khan et al. (2004) enlisted in their overview of remediation technologies solidification/stabilization, vitrification, electrical process, phytorremediation bio-slurry reactors andencapsulation. Diels et al. (2002) proposed the use of sludge reactors for non-saturated soils, using sulfate reducing bacteria SRB, as well as in situ heavy metals immobilization using SRB as well.

⇑ Corresponding author.
E-mail address: ltorresb@ipn.mx (L.G. Torres). 1474-7065/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.pce.2011.02.003

Soil washing is one ofthe few permanent treatment alternatives to remove metal contaminants from soils (Dermont et al., 2008). Other methods reported include hot water soil washing (Osokov and Bozzelli, 1994) which could be followed by hydrogen peroxide oxidation for Cr(VI) treatment (Rorck et al., 2001). Many methods consist in the extraction of metals from soils using soil washing (SW), followed by techniques...