Comparing sorption capacity of sorbent materials. Batch sorption experiments were carried out to screen the sorbents for their sorption capacity as a potential passive dosing reservoir. The detailed procedure is presented in Section S2, SI. Briefly, in a 20 mL amber glass vial, sorbent was immersed in 10 mL of 100 µg/L of C12-BAC in 5 mM CaCl2 solution (except a HPTLC piece, which was placed in a 50 mL glass beaker covered tightly with aluminum foil). After shaking for 24 h (i.e., for PES membrane, HPTLC plate, C18 fiber, SDB RSP membrane, C18 membrane, FKS, FKE and XAD2) or 72 h (i.e., for PE mesh, Nylon mesh, PET mesh, PPS mesh), water samples were taken and quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) as described in Section S6, SI. The concentration in the sorbents was obtained based on the mass balance calculation. The experiment was performed in duplicate.