A new Sr(II) ion-imprinted polymer grafted onto potassium titanate whiskers: Synthesis and adsorption performance for the selective separation of strontium ions

Abstract

Surface ion-imprinting technology was applied to prepare a new Sr(II) ion-imprinted polymer [Sr(II)-IP] by grafting chitosan-Sr(II) onto potassium titanate whiskers. The imprinting mechanism of the prepared polymer was examined, using infrared spectroscopy (IR), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The effects of pH and contact time were examined, together with the adsorption capacity and selectivity of the imprinted polymer. The adsorption isotherms could be fitted by the Langmuir model, with the dimensionless separation factor RL indicated favourable adsorption. In addition, the kinetic data were fitted more closely by the pseudosecond- order kinetic model rather than the pseudo-first-order model. The values of the Gibbs' free energy (ΔG0), standard entropy (ΔS0) and standard enthalpy (ΔH0) calculated from the adsorption data suggested that the adsorption of Sr(II) onto Sr(II)-IP was a spontaneous and endothermic process. The relative selectivity coefficients of Sr(II)-IP for Sr(II)/Cs(I) at different initial concentrations were 95.8, 320 and 1428.6, respectively, which were far greater than that of the non-imprinted polymer (NIP).