Removal of Steriod Hormones by Activated Carbon Adsorption—Kinetic and Thermodynamic Studies

The mechanism, isotherms and kinetics of removal of two endocrine disrupting chemicals, 17β-estradiol (E2) and 17αethinyloestradiol (EE2) by activated carbon adsorption were investigated in an agitated non-flow batch adsorption studies. Mathematical models were used to describe the adsorption phenomenon with the kinetic and thermodynamic parameters evaluated using the adsorption equilibrium data at varying temperatures. Higher adsorption rates were achieved at acidic to neutral pH ranges, with the sorption kinetic data showing a good fit to the pseudo second order rate equation and the Langmuir adsorption isotherm model for both E2 and EE2. The Gibbs free energy were –16.68 kJ/mol and –17.34 kJ/mol for E2 and EE2 respectively. The values of enthalpy for both E2 (84.50 kJ/mol) and EE2 (90 kJ/mol) indicated a chemical nature of the sorption process. Both the isotherm and thermodynamic data obtained all supported the mechanism of adsorption of E2 and EE2 to be mainly chemisorptions supported by some physical attractions.