Abiotic transformation of 17α-ethynylestradiol in the presence of vitamins and vegetable materials

Abstract

Estrogens are discharged consistently from wastewater treatment plants and other sources into surface waters, impacting reproduction and development in humans and wildlife populations at trace concentrations (nanogram per liter). Rabbit food (RF) was previously found to abiotically transform estrogens, but the specific functional components remain unknown. This study aimed to identify vitamins and vegetable materials capable of transforming the model estrogen 17α-ethynylestradiol (EE2). Individual vitamins and vegetable mixtures were incubated with EE2 solutions and analyzed via LC-MS/MS. Transformation capacity was evaluated along with process optimization. Highest transformation was observed with vitamin B complex, whereby 23% of initial EE2 was transformed into unknown products. In the presence of a solid phase, the fraction of EE2 extractable after exposure to vitamins D3 and C were 21.3 and 18.6%, respectively. As for vegetable materials, the lowest observed transformation capacity, mt, was for mint. On the other hand, carrot leaves, and corn had comparable mt values to those of RF, while the mt value for radish leaves exceeded the value for RF by 16%. Vegetables used in this study are considered inexpensive materials, which were found to promote the removal of EE2 via enhanced adsorption and/or catalytic reaction, these insights can facilitate development of green water treatment technologies to remove unmetabolized estrogens. Further optimization studies found dose to impact treatment, whereas temperature from 25 to 45 °C showed negligible effects, while extreme acidic/alkaline conditions reduced efficacy significantly, indicating a pH dependence.

Keywords

• Vegetable
• Vitamins
• Transformation
• Estrogens
• Sorption
• Water purification