<br/>Pharmaceuticals and personal care products (PPCPs) have received increasing attention as trace persistent organic contaminants in wastewater effluent and natural water sources due to their resistance to biodegradation and convention treatment procedures. While advanced oxidation processes (AOPs) are capable of completely mineralizing the recalcitrant contaminants, the current technologies are usually expensive and impractical to scale up for municipal wastewater treatment applications. For example, classic Fenton reaction generates hydroxyl radicals by utilizing soluble Fe2+ and H2O2 for oxidizing organic compounds. However, the reaction requires a strictly acidic pH range (3-5) and is limited by a subsequent Fe(III) precipitation that hinders the production of hydroxyl radicals. The use of heterogeneous catalyst for Fenton oxidation offers an alternative strategy to solve or minimize these problems. In this study, iron sulfide minerals, e.g., mackinawite (FeS), are utilized as Fenton reagents to catalyze the degradation of trimethoprim, a common antibiotic compound. Well mixed batch and flow-through bench scale reactors are used to investigate the degradation pathway and kinetics of trimethoprim in the heterogeneous system. The dependence of trimethoprim removal on the initial solution pH are examined by adjusting the suspension pH from 2 to 8. The efficiency of Fenton oxidation are also be tested at varied FeS/H2O2 ratios under both dark and visible light illumination conditions. The disappearance of trimethoprim and product formation in the aqueous solution are analyzed by Orbitrap-based LC- MS/MS. The reactivity and stability of iron sulfide catalysts are evaluated by bulk and surface characterization using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X- ray photoelectron spectroscopy (XPS). By demonstrating the feasibility of using iron sulfides as Fenton reagents, this study may allow commercially viable forms of novel heterogeneous catalyst to be developed for municipal water and wastewater treatment containing PPCPs.

Degradation of trimethoprim by heterogeneous Fenton reaction using iron sulfide catalysts

251st National Meeting (2016)

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