Electrokinetic Modeling of Heavy Metals

Jose Migxjel RooRfouEz-MAROTO and Carlos Vereda-Alonso 

Logically, the ionic current that flows through the soil has to be converted to an electronic current carried by the electrons through the electrodes and the external wires that connect this electrical circuit to the power supply. This change occurs at the electrode/electrolyte interface in the electrode wells. An electrochemical reduction reaction takes place at the cathode, which accepts electrons from the external 

Electrochemical Remediation Technologies for Polluted Soils, Sediments and Groundwater, Edited by Krishna R. Reddy and Qaudio Cameselle Copyright 2009 John Wiley Sons, Inc. 

As suggested by the above paragraph, other types of phenomena affect the previously described transport mechanisms of the contaminants toward the electrodes. These are the physical-chemical interactions, both between different compounds in the aqueous phase and between these aqueous species and the sohd phases of the soil system. Some of these interactions are precipitation, acid-base, complex formation and redox reactions, adsorption, and ion exchange and surface complexation reactions. 

as expected, the design, operation, and performance of the EKR system are not easy. Mathematical models are necessary in order to gain a better understanding of the processes that occurs in the EKR and to allow predictions for the field-scale remediation. Generally, it is a good policy to keep the mathematical model as simple as possible while adequately describing the behavior of the main parameters of the system (principle of parsimony). Thus, models with relatively simple transport equations and few equilibrium equations are able to predict the evolution of parameters such as the rate of recovery of the toxic ion, the maximum recovery, the rate of acid addition, and the energy requirements. The equation of mass conservation for a pore water solute species (e.g. an ion) in an EKR system can be expressed as follows  

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Al-Hamdan AZ, Reddy KR. (2005). Surface speciation modeling of heavy metals in kaolin Imphcations for electrokinetic soil remediation processes. Adsorption 11 529-546. 

Vereda-Alonso C, Rodriguez-Maroto JM, Garcla-Delgado RA, Gomez-Lahoz C, Garcia-Herruzo F. (2004). Two-dimensional model for soil electrokinetic remediation of heavy metals. Apphcation to a copper spiked kaolin. Chemosphere 54(7) 895-903. 

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