How crucial is the impact of calcium on the reactivity of iron-organic matter aggregates? Insights from arsenic

JOURNAL OF HAZARDOUS MATERIALS

卷:404

Article

Beauvois, Anthony^1,2,3  Vantelon, Delphine²  Jestin, Jacques^3,4  Bouhnik-Le Coz, Martine¹  Catrouillet, Charlotte¹  Briois, Valerie²  Bizien, Thomas²  Davranche, Melanie¹ 

[1] Univ Rennes, CNRS, Geosci Rennes, UMR 6118, F-35000 Rennes, France

[2] Synchrotron SOLEIL, Lorme Merisiers, St Aubin BP48, F-91192 Gif Sur Yvette, France

[3] CEA Saclay, Lab Leon Brillouin, F-91191 Gif Sur Yvette, France

[4] Inst Laue Langevin, 6 Rue Jules Horowitz, F-38000 Grenoble, France

关键词: Fe-OM colloids;    Adsorption isotherms;    Ferrihydrite;    Fe-oligomers;    EXAFS;    SAXS;    Ca interactions;   

DOI  :  10.1016/j.jhazmat.2020.124127

来源: Elsevier

【 摘 要 】

nvironmental iron-organic matter (Fe-OM) aggregates play a major role in the dynamic of pollutants. Nowadays, there is a lack of information about the control exerted by their structural organization on their reactivity towards metal(loid)s and in particular, the impact of major ions, such as calcium. The sorption capacity of mimetic environmental Fe-OM-Ca aggregates was investigated relative to the Fe/organic carbon (OC) and Ca/Fe ratios using As as a probe. It was shown that Fe speciation is the key factor controlling the reactivity of Fe-OM-Ca aggregates regarding the high affinity of Fe(III)-oligomers towards As and the high sorption capacity of ferrihydrite-like nanoparticles. Moreover, when it occurs at high concentration, Ca competes with Fe for OM binding leading to an increase in the amount of ferrihydrite-like nanoparticles and binding site availability. As a consequence, Ca not only impacts the ionic strength but it also has a dramatic impact on the structural organization of Fe-OM aggregates at several scales of organization, resulting in an increase of their sorption capacity. In the presence of high amounts of Ca, Fe-OM-Ca aggregates could immobilize pollutants in the soil porous media as they form a micrometric network exhibiting a strong sorption capacity.

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