Mesoporous Fe-doped MgO nanoparticles as a heterogeneous photo-Fenton-like catalyst for degradation of salicylic acid in wastewater

Authors: SILVA, MANOJ - Lehigh University; BALTRUS, JOHN - US Department Of Energy; Williams, Clinton; Knopf, Allan; ZHANG, LIHUA - Brookhaven National Laboratory; BALTRUSAITIS, JONAS - Lehigh University

Submitted to: Applied Catalysis B: Environmental
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/25/2021
Publication Date: 5/8/2021
Citation: Silva, M., Baltrus, J., Williams, C.F., Knopf, A.L., Zhang, L., Baltrusaitis, J. 2021. Mesoporous Fe-doped MgO nanoparticles as a heterogeneous photo-Fenton-like catalyst for degradation of salicylic acid in wastewater. Applied Catalysis B: Environmental. 9(4). Article 105589. https://doi.org/10.1016/j.jece.2021.105589.
DOI: https://doi.org/10.1016/j.jece.2021.105589

Interpretive Summary: Trace organic compound, like pharmaceuticals, are ubiquitous in treated municipal wastewater. Current sewage treatment processes are not designed to remove low level concentrations of pharmaceuticals. A new porous material made from magnesium oxide and 5% iron has been shown to be a good catalyst for removing salicylic acid in the presence of UV light and hydrogen peroxide. The catalyst was found to be able to remove all salicylic acid from solution within 15 minutes and the catalyst was sound to maintain reactivity for more than five reaction cycles. Additionally, degradation of salicylic acid resulted in no untoward byproducts and the catalyst was conserved. The new catalyst has the potential for use in current wastewater treatment plants to remove trace organics prior to environmental discharge.

Technical Abstract: Mesoporous Fe-doped MgO nanoparticles were synthesized using a facile sol-gel method and utilized for photo-Fenton-like degradation of salicylic acid (SA). The MgO surface dissolution facilitated an increase in the pH under the reaction conditions that allowed the Fe-MgO catalyst to be active without detectable iron leaching. Under simulated solar radiation, SA was completely degraded with an initial rate constant of 0.048 min-1 at the optimal reaction conditions of 500 ppm loading of 5% Fe-MgO, 20 mM H2O2 concentration, and 50 ppm SA concentration. The catalyst was stable over 5 reaction cycles. The Fe-MgO catalyst was shown to have a surface area up to 171 m2/g and contain hematite (Fe2O3) nanoparticles with octahedrally coordinated iron catalytic centers, as inferred from diffuse reflectance UV-vis measurements. Post-reaction catalyst characterization showed that some Fe2+ was present in the catalyst due to the redox cycle during the chain initiation and propagation steps of the reaction.