COUPLING ELECTROKINETICS AND IRON NANOPARTICLES FOR THE REMEDIATION OF CONTAMINATED SOILS

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Overview of in situ and ex situ remediation technologies for PCB-contaminated soils and sediments and obstacles for full-scale application

Publication . Gomes, Helena I.; Ferreira, Célia; Ribeiro, Alexandra B.

Polychlorinated biphenyls (PCB) are persistent organic pollutants used worldwide between the 1930s and 1980s. Although their use has been heavily restricted, PCB can be found in contaminated soils and sediments. The most frequent remediation solutions adopted are “dig and dump” and “dig and incinerate”, but there are currently new methods that could be more sustainable alternatives. This paper takes a look into the remediation options available for PCB-contaminated soils and sediments, differentiating between biological, chemical, physical and thermal methods. The use of combined technologies was also reviewed. Most of them are still in an initial development stage and further research in different implementation issues is needed. There is no single technology that is the solution for PCB contamination problem. The successful remediation of a site will depend on proper selection, design and adjustment of the technology or combined technologies to the site characteristics.

2013Journal article

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Numerical prediction of diffusion and electric field-induced iron nanoparticle transport

Publication . Gomes, Helena I.; Rodríguez-Maroto, José Miguel; Ribeiro, Alexandra B.; Pamukcu, Sibel; Ferreira, Célia

Zero valent iron nanoparticles (nZVI) are considered very promising for the remediation of contaminated soils and groundwaters. However, an important issue related to their limited mobility remains unsolved. Direct current can be used to enhance the nanoparticles transport, based on the same principles of electrokinetic remediation. In this work, a generalized physicochemical model was developed and solved numerically to describe the nZVI transport through porous media under electric field, and with different electrolytes (with different ionic strengths). The model consists of the Nernst–Planck coupled system of equations, which accounts for the mass balance of ionic species in a fluid medium, when both the diffusion and electromigration of the ions are considered. The diffusion and electrophoretic transport of the negatively charged nZVI particles were also considered in the system. The contribution of electroosmotic flow to the overall mass transport was included in the model for all cases. The nZVI effective mobility values in the porous medium are very low (10 7 –10 4 cm2V 1 s 1 ), due to the counterbalance between the positive electroosmotic flow and the electrophoretic transport of the negatively charged nanoparticles. The higher the nZVI concentration is in the matrix, the higher the aggregation; therefore, low concentration of nZVI suspensions must be used for successful field application.

2015Journal article

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Nanoremediation coupled to electrokinetics for PCB removal from soil

Publication . Gomes, Helena I.; Fan, Guangping; Ottosen, Lisbeth M.; Ferreira, Célia; Ribeiro, Alexandra B.

2016Book part

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