Synthesis and characterization of Hg(II)-ion-imprinted polymer: Kinetic and isotherm studies

Hg(II)-ion-imprinted polymer (IIP) was prepared by the formation of a binary complex of mercury (imprint ion) with 4-(2-thiazolylazo) resorcinol (TAR) and thermally copolymerizing with methacrylic acid (monomer) and ethylene glycol dimethadrylate (crosslinker), and 2, 2’-azobisisobutyronitrile as initiator in cyclohexanol as porogen. Mercury(II) was leached with 0.5 M HCl–1 M thiourea. Control polymer (CP) was also prepared without using imprint ion. The prepared IIP and CP were characterized with FT-IR, microanalysis, SEM analysis and surface area measurement. The effect of pH, adsorption kinetic and adsorption isotherm of imprinted polymer and control polymer were studied. The mechanism for adsorption of mercury was found to follow Freundlich isotherm and pseudo first order model. The adsorption capacity of Hg(II) on IIP and CP is 125 and 57.6 µmol g-1, respectively. The relative selectivity factor (αr) values of Hg(II)/Zn(II), Hg(II)/Cu(II), Hg(II)/Ni(II) and Hg(II)/Co(II) are 62.5, 65.3, 64.6 and 70.6, respectively. The detection limit corresponding to three times the standard deviation of the blank was found to be 2.875 µg L-1. The IIP has been successfully applied for the recovery of trace Hg(II) in real water samples and those spiked with standards.