Three source waters, two model waters (Ultrapure (natural organic matter (NOM)-free)) water and Suwannee River NOM isolate by reverse osmosis (SR-NOM)) and a natural water (Colorado River water (CRW)), were tested. Those waters were selected to represent a relatively hydrophobic NOM (SR-NOM) and a relatively hydrophilic NOM (CRW) based on their specific ultraviolet absorbance (SUVA = UVA254/DOC) values. The adsorption of an estrogenic compound, 17β-estradiol (E2), on powdered activated carbons (PACs) was investigated. Kinetic and PAC dose-response experiments were performed with PACs at an initial concentration of 0.1 nM (27 ng L-1). Additional experiments were also performed at various initial concentrations ranging from 0.025 nM (6.8 ng L-1) to 5.0 nM (1360 ng L-1) to determine the effects of initial concentration on E2 adsorption. In separate experiments, 17β-estradiol was introduced to PAC as a pure component, in binary mixtures with other salts (NaCl, Na2SO4, and CaCl2), and under varying pH conditions (4.0, 7.5, and 11.0) to determine the effects of pH and background ions on E2 adsorption. Samples were measured by liquid scintillation counting using 3H radio-labeled E2. Without preconcentration, a method detection limit using the liquid scintillation counter was 0.005 nM (1.36 ng L-1), respectively. Increasing contact time and PAC dose improved compound removal. Activated carbon is a viable technology for water treatment plants.
Bibliographical noteFunding Information:
This work was funded by the American Water Works Association Research Foundation (Ms. Kim Linton, senior account manager, Project #2758). The authors would also like to thank Dr. Miles Orchinik (Department of Biology) for allowing us to use the scintillation counter at Arizona State University.
- Endocrine disrupting compound
- Powdered activated carbon
- Radio-labeled 17β-estradiol
- Water treatment