Synthesis, characterization, and adsorption properties of a Ce(III)-imprinted polymer supported by mesoporous SBA-15 matrix by a surface molecular imprinting technique

A new Ce(III) ion imprinted polymer (Ce(III)-IIP), which can be used for selective removal of Ce(III) from aqueous solutions, was successfully prepared based on the matrix material of ordered mesoporous silica SBA-15 by surface molecular imprinting technology. The prepared polymer was characterized by X-ray diffraction, transmission electron microscopy, Fourier transmission infrared spectrometry, and nitrogen adsorption-desorption isotherm. The results showed that Ce(III)-IIP kept a uniform framework mesoporosity of SBA-15 but a decrease in Brunauer-Emmett-Teller surface area, pore volume, and average pore diameter. Batch adsorption tests were researched on the effects of solution pH value, mass of sorbent, and contact time at different initial Ce(III) concentrations and temperatures. The kinetic data well fitted the pseudo-second-order kinetic model compared with the pseudo-first-order model. The adsorption isotherm fitted Langmuir model and the dimensionless separation factor R_L indicated favorable adsorption. In addition, the Gibbs free energy (ΔG⁰), entropy (ΔS⁰), and enthalpy (ΔH⁰) were calculated from the adsorption data. These values suggested that the adsorption of Ce(III) onto Ce(III)-IIP was a spontaneous and endothermic nature of the process. The relative selectivity coefficients for different metal ion were larger than that of the nonimprinted polymer, indicating that Ce(III)-IIP synthesized for Ce(III) had a higher selectivity specialism for this ion. (author)