Removal of Estrone from Water by Adsorption on Zeolites with Regeneration by Direct UV Photolysis

Abstract

Estrone is an endocrine-disrupting compound (EDC) that is suspected to have adverse effects on aquatic organisms. This work investigated the removal of estrone from water by adsorption onto hydrophobic molecular sieve zeolites followed by ultraviolet light (UV) photolysis to destroy the adsorbed estrone. A solvent-free analytical method employing solid phase micro-extraction (SPME) and gas chromatography (GC-FID) was utilized to analyze low estrone concentrations in water. Two types of zeolites, dealuminated Y (DAY) and silicalite-1, were evaluated for adsorption capacity and compared with Centaur® activated carbon (CAC). DAY showed the highest adsorption capacity, while silicalite-1 was the least effective in removing estrone. Moreover, DAY required four hours to reach adsorption equilibrium; much less than the eight days needed for CAC to reach equilibration. The Freundlich adsorption isotherm was found to best represent the data for adsorption of estrone on DAY. UV at λ = 254 nm degraded estrone in water much more effectively than long-wave UV (λ = 365 nm). Regeneration of the contaminant-saturated DAY was accomplished with λ = 254 nm UV light.