Adsorption of 17α-ethynyl estradiol and β-estradiol on graphene oxide surface: An experimental and computational study

Adsorption of endocrine disrupting chemicals (EDCs) such as 17 alpha-ethynyl estradiol and beta-estradiol on sp(2) hybridized graphene oxide (GO) sheets as an efficient adsorbent was carried out. The effect of different experimental parameters such as the concentration of adsorbent and adsorbate as well as pH of the medium were investigated. It was observed that both 17 alpha-ethynyl estradiol and beta-estradiol molecules interact with the aromatic skeleton of graphene oxide ring by hydrogen bonding and electrostatic interactions between the oxygen containing functional groups of GO and -OH groups of micropollutant molecules in addition to pi-pi interactions between the pi-electrons of graphene oxide and the aromatic rings of the micropollutant molecules. It was found that the adsorption was facilitated in acidic medium and maximum adsorption efficiency of GO was found to be 98.46% and 97.19% for 17 alpha-ethynyl estradiol and beta-estradiol, respectively at pH 3 within 50 min. Classical molecular dynamics (MD) simulations were performed to analyze the adsorption process in the molecular level to support the experimental findings. The results obtained from the computational study show good agreement with the experimental findings. (C) 2018 Published by Elsevier B.V.