The electrokinetic approach, for the extraction of metal ions from dispersed solid matrixes, has received extensive description in the scientific literature of the last twenty years. The application of electric fields of suitable intensity, through saturated portions of soils, can determine the displacement of charged species. In principle, this effect has two components: one is the electromigration, the other is the component due to the electroosmotic drag of the spatial ionic charge facing the charged surface of soil particles. In the case of electromigration, the electric field has essentially the role of “driving force” for the movement of ionic species through the water impregnating the dispersed solids and the soil in particular. The effect remains even if the solid matrix is finely divided. The application of this technology, when aimed to the removal of mercury present in metallic form, requires its prior dissolution, which can be facilitated by adding appropriate chemicals. Designing an intervention requires a preliminary speciation of the contaminant in the soil, as well as the execution of electrochemical tests at a laboratory scale. The analysis of soil with speciation of the pollutant was carried out following the approach proposed by Boszke et al. “Mercury mobility and bioavailability in soil from contaminated area”, Environmental Geology (2008) 55: 1075-1087. The soil analysis was repeated after the electrochemical laboratory test, for an assessment of the amount of removed Hg. In addition, results obtained with this method were compared with those acquired using the alternative EPA 3200 procedure for speciation. The electrochemical laboratory test was performed on approximately 400 kg of soil, and for a period of about three months. After treatment, the soil analysis showed a significant reduction of total Hg (approximately 60% of the total). Basing on these results, an intervention in the field is being planned: estimation of time required to achieve the objective of remediation has been based on the removal of mobile and mobilizable forms of Hg.
ELECTROKINETIC REMEDIATION OF SOILS CONTAMINATED BY MERCURY
FERRO, Sergio;ROSESTOLATO, Davide;DE BATTISTI, Achille;
2011
Abstract
The electrokinetic approach, for the extraction of metal ions from dispersed solid matrixes, has received extensive description in the scientific literature of the last twenty years. The application of electric fields of suitable intensity, through saturated portions of soils, can determine the displacement of charged species. In principle, this effect has two components: one is the electromigration, the other is the component due to the electroosmotic drag of the spatial ionic charge facing the charged surface of soil particles. In the case of electromigration, the electric field has essentially the role of “driving force” for the movement of ionic species through the water impregnating the dispersed solids and the soil in particular. The effect remains even if the solid matrix is finely divided. The application of this technology, when aimed to the removal of mercury present in metallic form, requires its prior dissolution, which can be facilitated by adding appropriate chemicals. Designing an intervention requires a preliminary speciation of the contaminant in the soil, as well as the execution of electrochemical tests at a laboratory scale. The analysis of soil with speciation of the pollutant was carried out following the approach proposed by Boszke et al. “Mercury mobility and bioavailability in soil from contaminated area”, Environmental Geology (2008) 55: 1075-1087. The soil analysis was repeated after the electrochemical laboratory test, for an assessment of the amount of removed Hg. In addition, results obtained with this method were compared with those acquired using the alternative EPA 3200 procedure for speciation. The electrochemical laboratory test was performed on approximately 400 kg of soil, and for a period of about three months. After treatment, the soil analysis showed a significant reduction of total Hg (approximately 60% of the total). Basing on these results, an intervention in the field is being planned: estimation of time required to achieve the objective of remediation has been based on the removal of mobile and mobilizable forms of Hg.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
