Removal of Estrone, 17β-Estradiol, and 17α-Ethinylestradiol from Water by Adsorption onto Chemically Modified Activated Carbon Cloths

This paper explores the applicability of unmodified and chemically modified activated carbon cloths (ACCs) for the removal of estrone, 17β-estradiol, and 17α-ethinylestradiol from water. In order to examine the influence of surface properties on hormone adsorption, chemical modification of ACCs with HNO3, HCl, or KOH was employed. Applied treatments increased the specific surface area and changed the content of oxygen functional groups. Increased content of acidic surface oxygen functionalities enhanced adsorption efficiency up to 30 % and had a more dominant influence on adsorption capacity than specific surface area. Adsorption of estrone, 17β-estradiol, and 17α-ethinylestradiol followed pseudo-second-order kinetic model, while the equilibrium adsorption data fitted well with the Freundlich isotherm model. Calculated mean sorption energy values of 1.4475, 1.3387, and 1.0541 kJ/mol, for E1, E2, and EE2 respectively, indicated that removal of selected hormones was dominated by physisorption mechanism. Obtained Langmuir adsorption capacities, 12.34, 12.66, and 11.11 mg/g for estrone, 17β-estradiol, and 17α-ethinylestradiol, respectively, as well as convenience of manipulation, recommend activated carbon cloth modified with HNO3 as an efficient adsorbent for removing estrogen hormones from the water.