%0 Journal Article
%A Martínez Boubeta, Carlos
%A Balcells, Luis
%A Beltrán Fínez, Juan Ignacio
%A Martínez Peña, G. I.
%A Virgiliou, C.
%A Kalaitzidou, K.
%A Vourlias, G.
%A Teran, F. J.
%A Salutari, F.
%A Spadaro, M. Chiara
%A Arbiol, J.
%A Simeonidis, K.
%T Real-time Cr(VI) monitoring and remediation using Fe3O4 nanoparticles: Insights into Fe-Cr Spinels
%D 2025
%@ 2214-7144
%U https://hdl.handle.net/20.500.14352/126510
%X An analytical approach for the rapid and remote determination of Cr(VI) in water samples is demonstrated using Fe3O4 nanoparticles and a cost-effective portable AC magnetometer. Cr(VI) reduction by surface Fe²⁺ leads to Fe/Cr precipitate formation, which alters the nanoparticles’ magnetic properties. Validation in natural water spiked with Cr(VI) showed a linear correlation between magnetic remanence and Cr(VI) concentrations from 0 to 10 mg/L, with a R2 value of 0.99. Limitations of the method emerged at loadings above 10 mg/g, where extensive chromite (CrxFe3-xO4) coverage reduced the magnetic hysteresis area. Advanced characterization and DFT calculations revealed changes in spin-dependent properties, including magnetization reversal, electrical conductivity and magnetoresistance. This robust correlation between collective magnetic properties and Cr(VI) exposure enables, for the first time, milligram-per-liter detection via ultra-fast AC magnetometry, paving the way for real-time insight into redox processes in liquid environments and novel strategies for environmental remediation.
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