Water crises has been identified as one of the largest risks in terms of global impact. The increasing world population, improving living standards, changing consumption patterns, and expansion of irrigated agriculture have become the main driving forces for the rising global demand for water. This has in turn led to the generation of diverse wastewater streams containing various contaminants and pathogens that are eventually discharged into watersheds. The threat to freshwater from many emerging contaminants has been increasing. Among these contaminants, pharmaceuticals and personal care products (PPCPs) are ubiquitous in wastewater. Advanced oxidation processes (AOPs) can be utilized for the degradation of organic contaminants that are otherwise recalcitrant to biological treatment in municipal, industrial, and agricultural wastewater. In this work mesoporous Fe-doped MgO nanoparticles were synthesized using a facile sol-gel method and utilized as a photo-Fenton-like catalyst for degradation of salicylic acid (SA). The unique aspect of this catalyst is that the support MgO surface dissolution led to an increase in the solution pH under the reaction conditions, which prevents iron leaching from the catalyst during reaction. Under simulated solar radiation, SA was completely oxidized 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. No intermediate metabolites were detected in the solution at the end of the reaction time period and the catalyst was stable over 5 reaction cycles. The mesoporous 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 using XPS and Uv-vis showed that some Fe2+ was present in the catalyst due to the redox mechanism of the Fenton reaction.

Mesoporous Fe-doped MgO nanoparticles as a heterogeneous photo-Fenton-like catalyst for oxidizing emerging pharmaceutical contaminants in wastewater

ACS Fall 2021

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