Two-Phase Ozonation for the Removal of Estrone, 17 beta-Estradiol and 17 alpha-Ethinylestradiol in Water Using Ozone-Loaded Decamethylcyclopentasiloxane

摘要

Ozonation has been proven effective for the removal of endocrine disrupting chemicals (EDCs) in water. However, conventional ozonation processes are still limited by ozone low solubility and stability in water. These limitations may be overcome by mixing a prior ozone-loaded non-polar solvent with the aqueous solution. This two-phase ozonation process combines Liquid-liquid extraction and Ozonation (LLO). Decamethylcyclopentasiloxane (D5) was chosen as the solvent to be charged with ozone for its non-toxicity, reusability and high ozone solubility. A concurrent LLO column reactor was designed for the simultaneous degradation of three endocrine disrupting chemicals (EDCs) in water: Estrone (E1), 17 beta-estradiol (E2) and 17 alpha-estradiol (EE2). Results showed that 98% of EDCs were removed effectively from a solution initially concentrated at 1 mg L-1. The efficacy of the degradation depends essentially of the column feeding flowrate, the ozone dose and the operating pH. The generation of by-products during EDCs degradation by LLO was also investigated in this study. For a complete removal of both EDCs and by-products, the dose of ozone had to be doubled.