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Journal Articles (Review Article) Geochimica et Cosmochimica Acta Year : 2023

Aluminum-induced colloidal destabilization of iron-organic matter nanoaggregates

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Abstract

The structural organization of heterogeneous and multiphase natural aggregates depends on the biophysicochemical conditions prevailing in the environment, with major ions playing a crucial role. In this study, the impact of aluminum (Al) on iron-organic matter (Fe-OM) aggregates was investigated since Al can interact with OM and can be incorporated in Fe-oxyhydroxides or adsorbed on their surface. Mimetic environmental Fe-OM-Al aggregates were synthesized at various [Fe] and [Al] with a constant [OM]. At low [Al+Fe], Fe-OM-Al aggregates exhibit a colloidal behavior. Within the aggregates, Fe is present as Fe(III)-oligomers and ferrihydrite-like nanoparticles whereas Al forms monomers, oligomers and small polymers, all bound to OM. The Al and Fe phases interacted with each other. At high [Fe+Al], the Fe(III)-oligomers and Al monomers/oligomers polymerized which increases the size and quantity of the ferrihydrite-like nanoparticles and Al polymers and then branched out the OM, resulting in a large settling network. The effect of Al on the Fe-OM aggregates structure could also have an impact on the fate of pollutants. The occurrence of Al amorphous hydroxides and the increase in ferrihydrite-like nanoparticles lead to a higher availability of surface reactive sites and subsequently to an increase in the sorption capacity of the Fe-OM aggregates for pollutants that exhibit a greater affinity for minerals than for organics.
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insu-03932430 , version 1 (10-01-2023)

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Anthony Beauvois, Delphine Vantelon, Jacques Jestin, Aurélien Dupont, Valérie Briois, et al.. Aluminum-induced colloidal destabilization of iron-organic matter nanoaggregates. Geochimica et Cosmochimica Acta, In press, ⟨10.1016/j.gca.2023.01.005⟩. ⟨insu-03932430⟩
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