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Distinctive arsenic(V) trapping modes by magnetite nanoparticles induced by different sorption processes
Yuheng Wang1, Guillaume Morin, Georges Ona-Nguema
1Institut de Minéralogie et de Physique des Milieux Condensés, UMR 7590, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie - Université Paris Diderot, Campus Jussieu, 4 place Jussieu, 75005 Paris, France. yuheng.wang@epfl.ch
Arsenic immobilization on magnetite nanoparticles involves both adsorption and precipitation. Precipitation leads to higher arsenic uptake by incorporating arsenate into magnetite-like structures, crucial for water treatment technologies.
Area of Science:
- Environmental Science
- Geochemistry
- Materials Science
Background:
- Arsenic sorption on iron oxides like magnetite is key for arsenic immobilization in natural and engineered systems.
- Understanding arsenic speciation on magnetite is vital for effective water treatment.
Purpose of the Study:
- To investigate Arsenic(V) speciation on magnetite nanoparticles under adsorption and precipitation conditions.
- To elucidate the mechanisms of arsenic uptake by magnetite.
Main Methods:
- X-ray absorption fine structure (XAFS) spectroscopy to determine arsenic speciation.
- Transmission electron microscopy (TEM) to observe nanoparticle morphology and structure.
Main Results:
- Adsorption resulted in inner-sphere bidentate and outer-sphere complexes.
- Precipitation led to arsenate incorporation into magnetite-like structures, increasing with arsenic loading.
- TEM revealed amorphous coatings and small nanoparticles in precipitation samples.
Conclusions:
- Precipitation enhances arsenic uptake on magnetite nanoparticles significantly more than adsorption.
- Arsenic incorporation into magnetite-like clusters and nanoparticle formation are key mechanisms.
- Findings are essential for developing advanced arsenic water treatment technologies.
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