Either used as nano-carriers in blood, depolluting agents in groundwaters or nanofertilizers in soils engineered nanoparticles (ENPs) are prone to a growing interest that explains their multiple uses as well as their increasing industrial production. The very small size of ENPs (having at least one space dimension <100nm) gives rise to some exceptional physicochemical properties that ensue from their high reactivity. In environmental and agricultural fields, where iron oxide nanoparticles (IONPs) are particularly used, this reactivity is directly related to their adsorption capacity, which is of prime interest regarding soil contamination and soil recovery issues. Considering the peculiar role of copper (Cu) in soils, we investigated the specific relationships that exist between IONPs and Cu. Most particularly, this study aims at understanding how pH, Cu concentration and Fe3O4-NPs natural coatings drive Cu adsorption to IONPs. In a primary step, eight nm-sized Fe3O4-NPs were synthesized using a co-precipitation method and thoroughly characterized with TEM, XRD, FT-IR and BET while in a second stage Cu-adsorption tests were conducted through ultrafiltrations (<2kDa) and monitored with ICP-MS analyses. In these experiments, four types of IONPs were investigated regarding their mineralogy and the nature of their coating. They were tested with four copper concentrations (0.01, 0.05, 0.1 and 0.5mM) and five different pH values (3.5; 5; 6; 7 and 8). According to the results, un-adsorbed Cu decreases with increasing pH values and about 100% of Cu is adsorbed to IONPs at high pH values. Although the trend looks repeatable regardless NPs’ coating and Cu concentrations, each NP-type may have its typical pHpzc value and the amount of Cu adsorbed to IONPs is also likely to be related to the number of available adsorption sites.

Iron oxide nanoparticles

Reactivity

Source

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Rare earth elements as tracers of active colloidal organic matter composition

Environmental Chemistry (2019)

Charlotte Catrouillet Hélène Guénet Anne‐Catherine Pierson‐Wickmann Aline Dia Martine Bouhnik-Le Coz

Environmental contextThe origin of organic matter at Earth’s continental surface can be either terrestrial or microbial, and its precise composition can influence its reactivity towards metals. We investigated the potential of rare earth elements to fingerprint the origin of various organic matters through their reactivity and composition. The rare earth element patterns can be useful tools to determine the reactivity and also pristine source of natural organic matter. AbstractRare earth elements (REEs) have been shown to be efficient tracers of the functional sites and/or complexes formed on humic molecules. In the present study, we test the potential of REEs to be used as tracers of the sources of humic substances (HSs). Three types of organic matter (OM) of terrestrial and microbiological origin were tested. The experiments of REEs binding to the HSs were combined with size-fractionation experiments. The REE patterns were the most fractionated in the <10kDa fraction. For Leonardite humic acid (LHA) and Aldrich humic acid (AHA), the REE patterns were consistent with the REEs binding to strong but low density sites for a low REE/C loading. By contrast, for Pony Lake fulvic acid (PLFA), the REE pattern was similar to the REE pattern developed onto a bacteria cell surface and was attributed to the REEs binding to phosphate surface sites. Fluorescence and elemental analysis of PLFA showed that the <10kDa fraction was the fraction with the stronger microbiological character, which suggested the REEs were probably bound to PLFA through REE-phosphate complexes. Such results therefore provide a new possibility for the use of REEs to assess an OM source without the need to perform numerous or complex analytical methodologies.

10.1071/en19159

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Citations (19)

Trinidad mud volcanoes: where do the expelled fluids come from?

Geochimica et Cosmochimica Acta (1999)

Aline Dia Maryse Castrec‐Rouelle Jacques Boulègue Patricia Comeau

Mud volcano

Trace element

Radiogenic nuclide

Isotopes of strontium

Isotope Geochemistry

10.1016/s0016-7037(98)00309-3