InterPore2021

Electrokinetic delivery of reactants in porous media: solution chemistry controls transport, mixing and degradation

3 Jun 2021, 14:40

1h

Poster (+) Presentation (MS18) Innovative Methods for Characterization, Monitoring, and In-Situ Remediation of Contaminated Soils and Aquifers Poster +

Speaker

Mr Riccardo Sprocati (Technical University of Denmark)

Description

Electrokinetic phenomena occur in porous media as a result of the application of electric potential gradients. This technique has great potential for remediation of soil and groundwater even in challenging low-permeability porous media. The applied, low-intensity electric fields can enhance the transport of contaminants and the delivery of reactants and amendments for in situ (bio)degradation.
In this work we focus on electromigration, typically the most important mechanism of electrokinetic transport in subsurface porous media, and we experimentally demonstrate that changes in chemical conditions such as the concentration of a background electrolyte in the pore water of a saturated porous medium, control the macroscopic transport of charged tracers and reactants [1]. In a first set of experiments, we demonstrate that during electrokinetics the differences between the concentration of a tracer electrolyte and a background solution can significantly influence the delivery of the injected tracer, its spatial distribution and its mixing behavior with respect to a comparable scenario of advective-dispersive transport. In a second set of experiments, we show the implications of such electrokinetically-induced charge interactions for a reactive system, considering chemical oxidation of a non-charged organic compound (glucose) by a charged reactant (permanganate). The experimental results are quantitatively interpreted with numerical simulations, performed with the multiphysics and multicomponent model NP-Phreeqc-EK [2]. The outcomes of this study open interesting perspectives on electrokinetic approaches to design and implement effective delivery and remediation strategies in subsurface porous media [3].

References

[1] Sprocati, R., Gallo, A., Sethi, R., & Rolle, M. (2021). Electrokinetic Delivery of Reactants: Pore Water Chemistry Controls Transport, Mixing, and Degradation. Environmental Science & Technology, 55 (1), 719–729.
[2] Sprocati, R., Masi, M., Muniruzzaman, M., & Rolle, M. (2019). Modeling electrokinetic transport and biogeochemical reactions in porous media: A multidimensional Nernst–Planck–Poisson approach with PHREEQC coupling. Advances in Water Resources, 127, 134-147.
[3] Sprocati, R., Flyvbjerg, J., Tuxen, N., & Rolle, M. (2020). Process-based modeling of electrokinetic-enhanced bioremediation of chlorinated ethenes. Journal of Hazardous Materials, 397, 122787.