Selective Adsorption of Co(II) by Mesoporous Silica SBA-15-Supported Surface Ion Imprinted Polymer: Kinetics, Isotherms, and Thermodynamics Studies

摘要

A novel surface ion imprinted adsorbent [Co(II)-IIP] using polyethyleneimine (PEI) as function monomer and ordered mesoporous silica SBA-15 as support matrix was prepared for Co(II) analysis with high selectivity. The prepared polymer was characterized by Fourier transmission infrared spectrometry, scanning electron microscopy, X-ray diffraction and nitrogen adsorption-desorption isotherm. Bath experiments of Co(II) adsorption onto Co(II)-IIP were performed under the optimum conditions. The experimental data were analyzed by pseudo-first-order and pseudo-second-order kinetic models. It was found that the pseudo-second-order model best correlated the kinetic data. The intraparticle diffusion and liquid film diffusion were applied to discuss the adsorption mechanism. The results showed that Co(II) adsorption onto IIP was controlled by the intraparticle diffusion mechanism, along with a considerable film diffusion contribution. Langmuir, Freundlich and Dubinin-Radushke- vich adsorption models were applied to determine the isotherm parameters. Langmuir model fitted the experiment data well and the maximum calculated capacity of Co(II) reached 39.26 mg/g under room temperature. The thermodynamic data were indicative of the spontaneousness of the endothermic sorption process of Co(II) onto Co(II)-IIP. Co(II)-IIP showed high affinity and selectivity for template ion compared with non imprinted polymer (NIP).