Characterization of molecularly imprinted and nonimprinted polymer submicron particles specifically tailored for removal of trace 17β-estradiol in water treatment

This study investigated the potential use of molecularly imprinted polymer (MIP) submicron particles for the selective removal of trace 17β-estradiol (E2) in water treatment. Methacrylate-based MIP submicron particles were synthesized, in a one-step suspension polymerization procedure, using ethylene glycol dimethacrylate (EGDMA) as the cross-linker. After template removal, the particles could be used as a smart material for specific binding of E2. The submicron size of MIP particles facilitated uniform dispersion in water for up to 17 days. These particles were meritorious in mass transfer behavior, allowing phase partitioning of E2 molecules in water during a short treatment time. After 1-mL water samples of different E2 concentrations were treated with 20 mg of MIP particles for 2 min, recovery percentages as high as 97% ± 3% were achieved. The specific binding capacity of these MIP particles was determined to be 15 mg E2/g. Nonimprinted polymer nanoparticles were also evaluated for nonspecific binding of E2, using 0.5 mg in 1 mL of water, to attain 64% ± 3% efficiency in 3 min towards general water treatment. A simple capillary electrophoresis method was successfully developed for the characterization of MIP and NIP particles. Apparently the less negative the electrophoretic mobility, the higher binding efficiency and faster binding kinetics the particles would exhibit with E2 due to less hindered Brownian diffusion.