Removal of small-ring polycyclic aromatic hydrocarbons using cow and goat milk iron oxide nanoparticles

ABSTRACT

This work reports an environmentally friendly method for removing small-ring polycyclic aromatic hydrocarbons (PAHs) using iron oxide nanoparticles (IONPs) synthesized from pasteurized cow and goat milk and iron salts. IONPs were prepared at room temperature using FeSO₄ (2.0 g in 500 mL) and 10.0 mL of milk at pH 12. Results show that IONPs were formed with low crystallinity. The presence of Fe was confirmed through energy-dispersive X-ray spectroscopy results. Transmission electron microscopy and X-ray diffraction data show smaller semi-spherical nanometer-size particles in an aggregated state. The PAH removal process was monitored using a fluorescence spectrometer, and the results showed that the type of iron salt used (Fe²⁺/Fe³⁺) in the preparation of IONPs had no significant effect on the removal of model PAHs. However, the ring structure of the PAHs plays a role in the time taken for the removal process. All PAHs were removed from water efficiently with naphthalene, anthracene, and fluorene removal efficiencies of 75%, >90%, and 70%, respectively. The current study shows that IONPs formed using milk have the potential to be used to remove PAHs from water.

GRAPHICAL ABSTRACT

KEYWORDS:

• Polycyclic aromatic hydrocarbons
• cow milk
• goat milk
• green nanoparticles
• iron oxide nanoparticles

Acknowledgements

The authors would like to thank Mr. Tony Grady for the SEM-EDS data, Dr. Richard Littleton and Dr. Vitha Stanislav of Texas A&M University (Microscopy Imaging Center) for the TEM analysis of the samples, Dr. Joseph Reibenspies of Texas A&M University (X-ray Diffraction laboratory) for his assistance with the XRD analysis of the samples, and Dr. Angelica Benavidez of the University of New Mexico for the XPS analysis of the samples. Author contributions: Conceptualization, methodology development, data analysis, original draft preparation, H.F.; experimentation, data generation, and analysis, I.G.; and writing, figures, reviewing, and editing, H.F. and I.G. All authors have read and agreed to the content in the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Financial assistance from the PVAMU Research Office, Department of Chemistry Assistantship (IG), Welch Foundation, and DOE grant 419760-00001 is greatly acknowledged.