Degradation of Endocrine Disrupting Compounds (EDCs) Using FeIII‐TAML/Peroxide Catalysis

Abstract

Endocrine disrupting compounds (EDCs) are pollutants that show estrogenic activity at very low concentrations, and are emerging contaminants of concern in raw drinking water as well as treated wastewater. Reduction of EDCs in water by an environmentally benign method is an important green chemistry goal. This study investigated a new green catalytic approach, using the prototype iron-tetra-amido-macrocyclic-ligand (FeIII-TAML) activator as the foundation of peroxide, for destroying problematic EDCs and their byproducts. Three EDCs from pharmaceutical and personal care products (PPCP) group were selected for this study, namely Oxybenzone (OBZ), Triclosan (TRS) and Carbamazepine (CBZ). OBZ is commonly used as an ingredient in sunscreen and a variety of cosmetic products. TRS is an antibacterial and antifungal agent used in various personal care and consumer products. CBZ is an anticonvulsant and mood-stabilizing drug. This study has indicated that OBZ and TRS were rapidly destroyed by FeIII-TAML at concentrations 20nM, 40nM, 80nM, 200nM and 400nM, and H2O2 (4mM). A higher FeIIITAML concentration used in the reaction led to a faster removal rate of OBZ and TRS as well as their byproducts. The initial byproducts formed during the oxidation of OBZ and TRS were analyzed by liquid chromatography-mass spectrometry (LCMS). The initial byproduct of OBZ with mass to charge ratios (m/z) of 354 and 340 had little to no estrogenic activity as established by yeast estrogen screen (YES) assay. The initial byproduct of TRS with m/z ratio of 160.8 and 162.8 was suspected to be 2,4-dichlorophenol, a highly toxic compound. Estrogenic activity of TRS as well as its byproduct could not be tested by YES assay. CBZ was unable to be removed by FeIII-TAML / H2O2 catalysis. A degradation of mixed EDCs (OBZ + TRS, OBZ+TRS+CBZ) was performed using a concentration of 40nM FeIII-TAML and 4mM H2O2. Complete removals of both OBZ and TRS were achieved within 60 minutes. CBZ had no effect to the degradation rate of TRS and OBZ. In order to simulate real life condition, mixture of three EDCs (OBZ+TRS+CBZ) was dissolved in synthetic wastewater treatment plant (WWTP) effluent. FeIII-TAML (40nM) was consumed within 15 minutes reaction time. OBZ and TRS were removed by 97% and 77% respectively. However, WWTP effluent had little to no effect to the degradation rate of both OBZ and TRS.