Modeling rare earth elements binding to humic acids with model VII

Type Article
Date 2021-04
Language English
Author(s) Marsac Rémi1, Catrouillet Charlotte1, Davranche Mélanie1, Bouhnik-Le Coz Martine1, Briant NicolasORCID2, Janot Noémie3, Otero-Fariña Alba4, Groenenberg Jan E.5, Pédrot Mathieu1, Dia Aline1
Affiliation(s) 1 : Univ Rennes, CNRS, Géosciences Rennes - UMR 6118, F-35000 Rennes, France
2 : Laboratoire de Biogéochimie des Contaminants Métalliques, Ifremer, Centre Atlantique, F44311 Nantes Cedex 3, France
3 : ISPA, Bordeaux Sciences Agro, INRAE, F-33140 Villenave d'Ornon, France
4 : School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
5 : Soil Chemistry and Chemical Soil Quality, Wageningen University, Wageningen University & Research (WUR), P.O. Box 47, 6700 AA Wageningen, the Netherlands
Source Chemical Geology (0009-2541) (Elsevier BV), 2021-04 , Vol. 567 , P. 120099 (13p.)
DOI 10.1016/j.chemgeo.2021.120099
WOS© Times Cited 20
Keyword(s) Rare earth elements, Lanthanides, Humic acid, Natural organic matter, Complexation, Modeling, PHREEQC, Model VII, Speciation, Competition, Copper, Aluminium, Iron, Carbonate

Rare earth elements (REE) naturally occur at trace levels in natural systems but, due to their increasing use in modern technologies, they are now released into the environment, and considered as emerging contaminants. Therefore, the development of numerical predictive models of their speciation in various physico-chemical conditions is required to predict their behavior, transport and potentially toxic effects on ecosystems. Because REE speciation is largely affected by natural organic matter, such as humic acids (HA), this study aimed at calibrating an advanced humic-ion binding model (Model VII) to allow predicting REE-HA binding in various pH conditions, ionic strength and [REE]/[HA], as well as presence of competitor ions. First, REE complexation to monodentate O-containing ligands was evaluated using the Irving-Rossotti equation, which provided constraints for the optimization of REE-HA binding parameters for Model VII. Predictive capacities of Model VII were demonstrated by successfully modeling the effects of various cations (Al3+, Fe3+, Cu2+ and Ca2+) and carbonates on REE-HA binding. The large range of physico-chemical conditions for which Model VII is applicable suggest that the present model parameters might be used to more accurately predict the role played by NOM on REE speciation in very contrasting environments, such as in groundwaters, rivers, estuaries, seawater, soils or sediments. Therefore, this study provides a valuable numerical tool to predict the fate of REE in the environment.

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Marsac Rémi, Catrouillet Charlotte, Davranche Mélanie, Bouhnik-Le Coz Martine, Briant Nicolas, Janot Noémie, Otero-Fariña Alba, Groenenberg Jan E., Pédrot Mathieu, Dia Aline (2021). Modeling rare earth elements binding to humic acids with model VII. Chemical Geology, 567, 120099 (13p.). Publisher's official version : , Open Access version :