Synthesis, characterization and removal of Cd(II) using Cd(II)-ion imprinted polymer

Abstract

A novel ion imprinted polymer (IIP), phenol–formaldehyde–Cd(II)–2-( p-sulphophenylazo)-1,8-dihydroxynaphthalene-3,6-disulphonate (PF–Cd(II)–SPANDS) has been synthesized for selective solid phase extraction (SPE) of Cd(II) from aqueous solutions. IIP was prepared by the copolymerization of phenol and formaldehyde in the presence of Cd(II)–SPANDS complex in acidic medium. This polymer has been characterized on the basis of FTIR, elemental analysis and surface area measurement. Subsequently, the imprinted Cd(II) was completely removed by leaching the dried and powdered imprinted polymer with 1 M HNO 3 or 0.01 M EDTA in 0.5 M HNO 3. Adsorption capacity was determined by batch experiments for Cd(II), Zn(II), Cu(II) and Hg(II) ions. The effect of pH, flow rate and equilibrium adsorption time was also studied for Cd(II). Adsorption equilibrium time was 50 min. The maximum adsorption of Cd(II) ions on to the imprinted polymer was 270 μg g −1. For comparison, the adsorption of metal ions was also studied on non-imprinted polymer (NIP). The adsorption capacity of IIP was found 59.2% higher than that of NIP for Cd(II) ion. However, for other investigated transition metal ions the capacity difference was not significant. The relative selectivity factor ( α r) values of Cd(II)/Zn(II), Cd(II)/Cu(II) and Cd(II)/Hg(II) are 7.4, 6.6 and 6.7, respectively which are greater than 1.