Electrokinetic Propagation of Acid and Base Fronts in Clayey Soil: An Experimental and Numerical Study
- PDF / 2,452,365 Bytes
- 27 Pages / 439.37 x 666.142 pts Page_size
- 10 Downloads / 196 Views
Electrokinetic Propagation of Acid and Base Fronts in Clayey Soil: An Experimental and Numerical Study Banambono Wilfried Forogo1,2 · Guillaume Stoltz1 · Nathalie Touze3 · Stéphane Bonelli1 Received: 25 November 2019 / Accepted: 23 July 2020 © Springer Nature B.V. 2020
Abstract This paper presents an experimental and numerical investigation of the electrokinetic propagation of acid or base fronts through clayey soil. The experimental study included measuring the electric current, the mass of water extracted, and the advance of the acid and base fronts in synthetic sediment composed of 25% kaolinite and 75% silt. The results show that the flux rate remains constant over time and that the medium acidifies with time. The numerical model is based on the transport equations and, by considering adsorption and auto-ionization of water, it describes the temporal evolution of pH in the specimen. The experimental evaluation of the adsorption isotherms allows us to calculate the retardation factor, which is 69 and 19.5 for the hydronium and hydroxyl ions, respectively. Given these retardation factors, the results of the numerical model are consistent with experimental results and show how the acid and base fronts evolve in a saturated porous medium. Numerical model results show that electromigration is the major contributor to the migration of ions in the porous medium during electrokinetic treatment. Keywords Electrokinetic · Electroosmosis · Electromigration · Clayey soil · pH · Langmuir isotherm
1 Introduction Electrokinetics refers to the application of voltage to a wet, porous medium. Different phenomena occur during electrokinetic treatment, such as electromigration, electroosmosis, electrophoresis, streaming potential, sedimentation potential, and water electrolysis (Glendinning et al. 2005). Electrokinetics is currently under study for * Banambono Wilfried Forogo [email protected]; [email protected] Guillaume Stoltz [email protected] 1
INRAE, Aix-Marseille université, UMR RECOVER, Aix‑en‑Provence, France
2
AFITEXINOV, Champhol, France
3
Université Paris-Saclay, INRAE, SDAR, Jouy‑en‑Josas, France
13
Vol.:(0123456789)
B. W. Forogo et al.
different applications, such as soil consolidation (Malekzadeh et al. 2016), sludge dewatering (Mahmoud et al. 2018), strengthening of dredged sediments (Flora et al. 2017), dredged-sediment depollution (Benamar et al. 2019), soil remediation (Villen-Guzman et al. 2018), and depollution of kaolinite spiked with lead (Azzam and Oey 2001). Electroosmosis, electromigration, and water electrolysis are typical phenomena exploited for these applications. Electroosmosis involves a flux of fluid in a matrix of charged particles from the ground and occurs upon applying an electric potential difference across the medium. Electromigration is the migration of ions due to the application of an electric potential difference across a material. Finally, the electrolysis of water generates a heterogeneous pH distribution in the medium by producing hydronium ions at
Data Loading...
