Fe(II)ion-imprinted copolymer gels - smart materials for Fe(II)/Fe(III) speciation in surface waters

The effect of template species - Fe(II) complexes with 4-(2-pyridylazo)resorcinol or 2,2 '-bipyridine as well as the functional monomers: acidic (methacrylic acid) and neutral (hydroxyethyl methacrylate) on the extraction efficiency and applicability of Fe(II) ion-imprinted polymers for iron speciation in surface waters is presented in this study. The polymers were synthesized by precipitation copolymerization of functional monomer, trimethylolpropane trimethacrylate (crosslinking agent) and 2,2 '-azo-bis-isobutyronitrile (initiator) in the presence of template and characterized by elemental microanalysis, SEM and Brunauer-Emmett-Teller analyses. Extraction efficiency was examined by batch solid-phase extraction. The equilibrium experimental data of adsorption processes with different synthesized sorbents were fitted by both Langmuir and Freundlich isotherms and are discussed from the viewpoint of possible bond formation between monomer and template species and the stability of the prepolymerization complex. Pseudo-first-order and pseudo-second-order kinetic models were tested to elucidate the possible controlling mechanism of the sorption process for different sorbents. Under the optimum conditions pH 7 and equilibrium time of 30 min the highest extraction efficiency and selectivity toward Fe(II) was achieved for Fe(II) ion-imprinted polymer containing methacrylic acid and Fe(II)-4-(2-pyridylazo)resorcinol complex as a template. The analytical procedure for Fe speciation was developed and validated with this sorbent. (c) 2021 Society of Industrial Chemistry.