TY - JOUR
T1 - Mobility and interaction of heavy metals in a natural soil
AU - Janetti, Emanuela Bianchi
AU - Dror, Ishai
AU - Riva, Monica
AU - Guadagnini, Alberto
AU - Sanchez-Vila, Xavier
AU - Berkowitz, Brian
N1 - Spanish Ministry of Science and Innovation [CSD2009-00065, GCL2009-1114]; Israel Science Foundation [221/11]; Politecnico di MilanoX. S. acknowledges financial support by the Spanish Ministry of Science and Innovation through the projects Consolider-Ingenio 2010 (ref. CSD2009-00065) and RARA-AVIS (ref. GCL2009-1114). B. B. acknowledges financial support from the Israel Science Foundation (Grant No. 221/11). M. R., A. G., and E. B. J. acknowledge financial support from the Politecnico di Milano (Project GEMINO, Progetti di ricerca 5 per mille junior).
PY - 2013/4
Y1 - 2013/4
N2 - We study the mobility and interaction under competing conditions observed for copper (Cu^{2+}) and zinc (Zn^{2+}) ions in the context of laboratory-scale experiments performed in natural soil columns. The experiments focus on the analysis of solute breakthrough curves (BTCs) obtained after injection of an aqueous solution containing similar concentrations of the two metal ions into a soil column fully saturated with double deionized water. Transport of the competing ions is tested for the same soil under aerobic and anaerobic conditions. Measurements show that the species with lower affinity for the soil, Zn^{2+}, migrates occupying all available adsorption sites, and is then progressively replaced by the ion with higher affinity, Cu^{2+}. The two ions are displaced in the system with different effective retardation. The slowest species replaces the sorbed ions, resulting in observed Zn^{2+} concentrations that display a non-monotonic behavior in time and which, for a certain period, are larger than the concentration supplied continuously at the inlet. In the absence of a complete geochemical characterization of the system, we show that the measured concentrations of both metals can be interpreted through simple models based on a set of coupled partial differential and algebraic equations, involving a small subset of aqueous and adsorbed species that are present in the system. Depending on the model considered, the relationship between aqueous and adsorbed ion concentrations is described at equilibrium by a Gaines-Thomas (GT) formulation, a competitive Sheindorf-Rebhun-Sheintuch (SRS) isotherm, or an Extended Langmuir (EL) isotherm, respectively. The GT formulation provides the best interpretation of the observed behavior among the models tested. We find that employing these simple models, which account only for the main governing reactive processes, allows reasonable estimation of the observed BTCs in experiments where only partial geochemical datasets are available.
AB - We study the mobility and interaction under competing conditions observed for copper (Cu^{2+}) and zinc (Zn^{2+}) ions in the context of laboratory-scale experiments performed in natural soil columns. The experiments focus on the analysis of solute breakthrough curves (BTCs) obtained after injection of an aqueous solution containing similar concentrations of the two metal ions into a soil column fully saturated with double deionized water. Transport of the competing ions is tested for the same soil under aerobic and anaerobic conditions. Measurements show that the species with lower affinity for the soil, Zn^{2+}, migrates occupying all available adsorption sites, and is then progressively replaced by the ion with higher affinity, Cu^{2+}. The two ions are displaced in the system with different effective retardation. The slowest species replaces the sorbed ions, resulting in observed Zn^{2+} concentrations that display a non-monotonic behavior in time and which, for a certain period, are larger than the concentration supplied continuously at the inlet. In the absence of a complete geochemical characterization of the system, we show that the measured concentrations of both metals can be interpreted through simple models based on a set of coupled partial differential and algebraic equations, involving a small subset of aqueous and adsorbed species that are present in the system. Depending on the model considered, the relationship between aqueous and adsorbed ion concentrations is described at equilibrium by a Gaines-Thomas (GT) formulation, a competitive Sheindorf-Rebhun-Sheintuch (SRS) isotherm, or an Extended Langmuir (EL) isotherm, respectively. The GT formulation provides the best interpretation of the observed behavior among the models tested. We find that employing these simple models, which account only for the main governing reactive processes, allows reasonable estimation of the observed BTCs in experiments where only partial geochemical datasets are available.
UR - http://www.scopus.com/inward/record.url?scp=84874703038&partnerID=8YFLogxK
U2 - https://doi.org/10.1007/s11242-013-0125-2
DO - https://doi.org/10.1007/s11242-013-0125-2
M3 - مقالة
SN - 0169-3913
VL - 97
SP - 295
EP - 315
JO - Transport in Porous Media
JF - Transport in Porous Media
IS - 3
ER -