Electrochimica Acta 86 (2012) 124–129 Contents lists available at SciVerse ScienceDirect Electrochimica Acta j ourna l ho me pag e: www.elsevier.com/locate/electacta Electrokinetic remediation using pulsed sinusoidal electric field Adrian Rojo ∗ , Henrik K. Hansen, Marcela Cubillos Departamento de Ingeniería Química y Ambiental, Universidad Técnica Federico Santa Maria, P.O. Box 110 V, Valparaíso, Chile a r t i c l e i n f o Article history: Received 15 October 2011 Received in revised form 13 April 2012 Accepted 18 April 2012 Available online 26 April 2012 Keywords: Electroremediation Alternating current Direct current Copper mine tailings a b s t r a c t In this work an electrokinetic remediation cell for copper mine tailings using sinusoidal electric field in pulses was analyzed. The sinusoidal electric field was obtained by applying simultaneously continuous- alternating voltages; in this work an alternating voltage of 50 Hz was applied. The system was tested considering the effect of: (1) pulses in an EKR with sinusoidal electric field, (2) the effective voltage of the sinusoidal electric field, and (3) the pulses ratio. According to the conditions studied in this investigation, the laboratory results showed that pulses in a sinusoidal electric field improves the EKR process, especially when the pulses and a polarity inversion in the sinusoidal electric field are present simultaneously, since both phenomena reduce polarization during the process. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction In 2009, the annual production of the copper mining industry in Chile has reached 5.39 million metric tons (MMT) of fine copper, representing 34% of the world production of this metal [1]. Much of this production is obtained by grinding and flotation processes, and according to the efficiencies of the current mining processes and the copper ore grades exploited, generates a variety of wastes that represent a considerable environmental liability. In the case of copper mine tailings, which can be characterized as low-grade ores, without any treatment are deposited in safe places such as dumps, ponds, etc. These deposits have been accumulating large quantities of waste, and represent a serious environmental risk due to their content of heavy metals, for example the copper content in typical residues from copper mining is in the interval 100–2000 ppm [2], and other metals found in elevated concentrations are Zn, As, Cd, Pb, and Fe. Consequently, since these wastes are not treated before disposal, they typically become unstable over time due to natural processes of oxidation, during the disposal in the ponds [3]. In the case of copper, the content of soluble copper is variable due to the heterogeneous origin of the mine tailings in the ponds, such as cop- per grades which depend on the original characteristics of the tails disposed, and aging of the tailings in the ponds. Unfortunately wastes not only have a damaging effect on hydro resources by natural leaching, but also generate effects on flora and fauna, and have serious effect on air quality by the generation of fugitive emissions of fine particles. The more complex case occurs ∗ Corresponding author. Tel.: +56 32 2654463; fax: +56 32 2654478. E-mail address: adrian.rojo@usm.cl (A. Rojo). when heavy metals leach into groundwater and rivers, because the distribution of these pollutants in the environment becomes fast and uncontrollable. Therefore action has to be taken to deal with the growing problem of accumulation of mining waste, and one possible way to treat this problem is to remediate in situ these wastes. This could both be of direct importance for the environment by excluding leaching of metals, but also a minimisation of raw materials if it could be possible to extract the metals during the remediation processes. One solution to this environmental problem is the conversion of the waste into a chemically stable solid by remediation processes which use electrokinetic phenomena. This principle has been used successfully during around 20 years for the treatment of heavy metal polluted soil [4–10]. In this case, the use of the electroremedi- ation technology will imply the periodic application of the method in order to remove the soluble heavy metal such as copper that will be generated with time. Therefore, the remediation action for this heterogeneous solid waste is to remove the soluble copper in the tailings and in this way making the final residue more stable. The objective of this work is the application using pulses of a sinusoidal electric field obtained by applying simultaneously continuous-alternating (DC–AC) voltages, in order to enhance the behavior of an EKR cell for copper mine tailings. The application of DC–AC electric field as power source for electroremediation of organic contaminants in soils and removal of nitrate complex has been investigated lately [11,12]. In the case of EKR with copper mine tailings; according to the magnitude of DC–AC voltages a periodic reversal of polarity of the system can be produced. This periodic phenomenon improves the efficiency of EKR technique with cop- per mine tailings [13,14], mainly because it reduces the polarization in the cell. On the other hand, if the electric field is applied in pulses 0013-4686/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.electacta.2012.04.070