A novel ion-imprinted polymer for selective removal of trace Fe(III) from Cr(III)-containing solutions

An ion-imprinted polymer (IIP) was synthesized by radical copolymerization for use in the removal of trace Fe(III) ions from Cr(III)-containing solutions. During the synthesis process, Fe(III) ions, acrylic acid and ethylene glycol dimethacrylate were employed as the template ions, functional monomer and cross-linker, respectively. The optimal mole ratio of acrylic acid to Fe(III) ions, which significantly affected the adsorption performance, was determined. The maximum static adsorption capacity of the polymer for Fe(III) ions was 114.25 mg g−1, with a selective factor (k) of 492.18 and a relative selective factor (k′) of 50.87 for Fe(III)/Cr(III). The Fe(III) ions removal efficiency could reach 94.43%, leading to a final Fe(III) concentration of 0.053 mg L−1 in the treated solution. After the removal process, the mass ratio of Cr(III) ions to Fe(III) ions was higher than 26, 000:1 in the solution, with an initial mass ratio of Cr(III) to Fe(III) ions of 1500:1.