Absorbability of estrone and 17beta-estradiol in water onto activated carbon.

With a view to reducing pollution in the aquatic environment, estrone (E1) and 17beta-estradiol (E2) were tested for their absorbability in water onto activated carbons (ACs) with various pore-size distributions. In batch-type adsorption measurements, all adsorption isotherms obtained were found to fit a Freundlich equation. In case of eight different kinds of commercial AC in pure water, the amount adsorbed at equilibrium concentration of 1 microg/L was in the range of 25.6-73.5mg/g for E1 and 21.3-67.6 mg/g for E2. In case of pre-used ACs in water sand-filtered for use as drinking water, the amount adsorbed at 1 microg/L was in the range of 3.5-8.2mg/g for E2. In the case of two commercial ACs in river water and in effluent from secondary clarifier at municipal sewage treatment plant (MSTP), both originally containing E2, was in the range of 0.1-0.2 and 0.3-1 microg/g, respectively, at 1 ng/L. The difference of amount adsorbed onto AC was discussed in view of hydrophobicity of target chemicals, specific surface area and mean pore diameter of AC, and the difference in the absorbability and the ratios of co-present substances for the target compound.