Clay mineral-based materials for mitigating mycotoxin contamination: Two photoinduced removal approaches for zearalenone and deoxynivalenol

Mycotoxins produced by certain fungi contaminate food, crops, and water, posing health risks and causing economic losses. Among the most prevalent, zearalenone (ZEN) and deoxynivalenol (DON) are difficult to remove with conventional adsorbents due to their relatively non-polar nature. Both toxins are associated with serious adverse effects, including endocrine disruption, immunotoxicity, and gastrointestinal damage. This study aims to develop a targeted removal approach for ZEN and DON and to elucidate the underlying mechanisms.

Knowing their large specific surface area, low cost, and good dispersibility, clay minerals have been employed as mineral supports. From this group, we focused on kaolinite-based materials, including a kaolinite-rich sample (M), synthetic calcined kaolinite nanotubes (MNC), halloysite purchased from Sigma-Aldrich (HS), and unpurified halloysite-containing sample (HD). The mineral supports were coated with approximately 20 wt% of TiO₂, g-C₃N₄ (GCN), or a TiO₂/GCN mixture for ZEN removal, and with TiO₂, Fe₂O₃, or a TiO₂/Fe₂O₃ for DON removal. For ZEN, a photodegradation approach using UV light was employed. In contrast, DON, being a more resistant toxin, required the addition of the oxidizing agent peroxymonosulfate (PMS, 2 mM) to achieve efficient degradation.

The GCN and TiO₂/GCN materials were the most effective for ZEN removal, with the MNC-based samples achieving 98.8% and 97.7% degradation, respectively, after 25 min of UV exposure. The mechanisms of ZEN degradation varied with the composite, but for the majority of materials O₂^•⁻ and •OH species played a major role. Importantly, incorporating an insulating clay mineral did not reduce photocatalytic efficiency; rather, the mineral interface appeared to enhance charge separation. Analysis of ZEN photodegradation pathways showed that oxidation and reactive oxygen species led to a breakdown of the carboxyl group and removed functional groups, forming various lower- and higher-mass intermediates [1]. Further degradation cleaved the aromatic ring, producing simpler oxygen-rich chains that can be ultimately mineralized to CO₂ and H₂O.

For DON removal, the MNC-based TiO₂/Fe₂O₃ samples were the most effective, removing 98.8% of the initial concentration after 45 min, while MNC-based samples containing only TiO₂ or Fe₂O₃ achieved 66.1% and 46.0%, respectively. Mössbauer spectroscopy and SEM confirmed the presence of the maghemite phase, showing that Fe₂O₃ loaded on the MNC support is nanosized, providing a large specific surface area for redox reactions and efficient PMS activation. Simultaneous ZEN and DON removal under UV light with PMS activation demonstrated that this approach is effective also for ZEN. Under visible light, DON was also efficiently removed, dropping below the detection limit within minutes using the MNC-based TiO₂/Fe₂O₃ sample.

The results demonstrated the potential of mineral support in photocatalysis and photoinduced chemical oxidation for ZEN and DON removal. Future research will focus on expanding the study on DON, elucidating its degradation mechanisms and pathways.

Acknowledgements
This project was supported by the National Science Centre Poland, under a research project awarded by Decision No. 2021/43/B/ST10/00868.

References
[1] K. Dziewiątka, J. Matusik, M. Herber, E.H. Hill, J. Kuc, G. Cempura, A. Jędras, Enhanced photodegradation of zearalenone with kaolin group-based nanotubular materials: Unveiling reaction mechanisms and pathways, Chemical Engineering Journal 506 (2025) 160198. https://doi.org/10.1016/j.cej.2025.160198.