Fe(III) 表面印迹硅胶聚合物的制备及其吸附性能研究

It is significant to remove irons in wastewater. In this study, a novel Fe (III) ion surface-imprinted silica gel polymer (VPA EGDMA IIP / SiO₂ ) was prepared via the surface imprinting technology by using vinyl phosphonic acid (VPA) as the functional monomer and ethylene glycol dimethacrylate (EGDMA) as the crosslinker. The synthesized imprinted silica gel polymer was used as a sorbent for selective adsorption of Fe^{3 +} from an aqueous solution. The imprinted polymer was characterized by Fourier transform infrared spectroscopy (FT IR), thermogravimetric (TG) analysis, scanning electron microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), and N₂ adsorption-desorption isotherms. The adsorption properties, such as the effect of solution pH, adsorption kinetic, adsorption isotherm, adsorption selectivity as well as the regeneration of sorbent were studied. The result shows that the prepared Fe (III) ion-imprinted polymer has good thermal stability when the ambient temperature is below 210 ℃ . The surface area and the pore volume of VPA EGDMA IIP / SiO₂ are greater than VPA EGDMA NIP / SiO₂ , and it may be attributed to the result that more recognition sites for the template Fe^{3 +} ions are formed on the sorbent surface. Furthermore, after adsorption, the surface area and the pore volume of IIP PA/ SiO₂ decreased, which is likely owing to the fact that Fe^{3 +} ions are combined with recognition sites on the sorbent surface. The adsorption results show that the pH value of the solution has an important influence on the adsorption process, and the maximum adsorption capacity of VPA EGDMA IIP / SiO₂ is obtained at a pH value of 2 in an aqueous solution with the maximum adsorption capacity 16. 12 mg / g. The adsorption process followed the pseudo-second-order kinetics equation and the Langmuir isotherm adsorption model. The adsorption of Fe^{3 +} on VPA EGDMA IIP / SiO₂ belongs to a rapid chemical adsorption process and the adsorption equilibrium is achieved within 8 min. The adsorption process is spontaneous, exothermic and entropy reduced. The relative selectivity coefficients for Fe(III) / Cr(III), Fe(III) / Mn(II), and Fe (III) / Zn (II) are 8. 9, 10. 75 and 12. 37, respectively, indicating that VPA EGDMA IIP / SiO₂ has a good recognition performance. Moreover, the adsorption capacity of the prepared sorbent does not decrease significantly after six repeated use, indicating the prepared adsorbent has excellent regeneration for Fe^{3 +} adsorption, which can selectively separate and recover from aqueous solution.