Synergistic pharmaceutical interactions with nanoscale iron nitrides and natural organic matter

Understanding how natural organic matter (NOM) shapes the environmental fate of reactive iron nitride nanoparticles (nFeN) is key to advancing sustainable remediation technologies. This study investigates the behavior and interactions of novel nFeN, and conventional nanoscale zero-valent iron (nZVI), in complex and contrasting real-world aquatic environments: the pristine, organic-rich La Guette peatland and the wastewater-impacted Egoutier urban watershed in France. The study mainly focuses on their interplay with NOM and emerging pharmaceuticals (PPs). Field aging of nFeN produced mainly magnetite, akaganeite, and chukanovite (up to 31, 21, and 47 wt%, respectively), with site-specific mineral profiles shaped by DOC type, hydrodynamics, and microbial activity. Regarding PPs, under higher-flow conditions, nFeN outperformed nZVI, combined with DOC, retaining up to 96 ng g −1 venlafaxine, 83 ng g −1 oxazepam, 51 ng g −1 carbamazepine, 44 ng g −1 diazepam, 17 ng g −1 metoprolol and paracetamol, and 13 ng g −1 tramadol. Elevated log K d (solid-liquid partition coefficient) values relative to log K oc (organic carbon to water partition coefficient) and log K ow (octanol-water partition coefficient) indicated that (i) interaction with NOM need to be considered for evaluating the PPs association with both Fe-based nanoparticles (NPs) and (ii) electrostatic interactions and ion exchange, rather than hydrophobicity, dominate cationic PPs binding by NPs. These findings highlight nFeN as a structurally robust yet environmentally responsive material for PP retention. The dataset also provides a valuable benchmark for designing nanocomposites incorporating nFeN, enabling evaluation of how porous supports alter its intrinsic performance under field conditions. • nFeN kept higher stability and broader PPs uptake than nZVI under field conditions. • Aging of nFeN and nZVI yielded magnetite, akaganeite and chukanovite as main phases. • The novel dialysis bag method recovers nFeN and nZVI byproducts in real field settings. • Lab/field studies reveal key DOC–NPs interactions crucial for contaminant removal.