Adsorption isotherms of 17β-estradiol on granular activated carbon (GAC)

The adsorption characteristics of three types of activated carbon for 17β-estradiol were studied by long term experiments to assess the time which is necessary to reach equilibrium between the solid and the liquid phase. The adsorption kinetics were measured by liquid scintillation counting using radio-labelled 17β-estradiol at various concentrations of 17β-estradiol in the ppt range. 17β-estradiol is quickly adsorbed and conditions close to equilibrium were reached after 50–180 min. The equilibrium concentrations were calculated to be at 49–81% of the initial concentration in the concentration range between 1 and 100 ng/l, with 0.51 ng/l for a 1 ng/l and between 5.9 and 14.6 ng/l for 100 ng/l initial concentration.