Preparation And Characterization Of Surface Ion-imprinted Polymers Based On Mesoporous Materials

With the continuous development of social economy,water pollution is becoming more and more serious.Adsorption method to the removal of metal pollution plays an important role because of its flexibility in operation and superior efficiency.However,conventional adsorbents have some disadvantages for the removal of heavy metals,such as low selectivity,poor hydrothermal stability and low reusability.In recent years,Ion imprinting technique has been widely applied because of high specificity.Among them,the surface imprinting technique is further studied because of its advantages that the binding site is limited to the surface of the material with good accessibility,the adsorption speed is faster,the recognition is better,the ion imprint is easier to elute.In this paper,surface-imprinted polymers were prepared by using silica gel or mesoporous SBA-15 as substrate materials via surface imprinting technology.The prepared polymer was characterized by Fourier transmission infrared spectrometry(FT-IR),Energy disperse spectroscopy(EDS),X-ray diffraction(XRD),Scanning electron microscope(SEM),Transmission electron microscope(TEM),Nitrogen adsorption–desorption isotherm,and Thermogravimetric analysis(TGA).Batch adsorption tests were investigated,including the equilibrium of adsorption time and adsorption capacity,selectivity,recycling performance and so on.The results are as follows:(1)A cobalt ion imprinted polymer was prepared using cobalt ion as the template,(3-Mercaptopropyl)trimethoxysilane as functional monomer,and epichlorohydrin as the cross-linking agent supported on silicon dioxide by surface imprinting technique and the structure of the polymer was characterized.The results of adsorption capacity showed that p H=5~6,the maximum static adsorption capacities of the imprinted polymer was 20.05 mg/g at 25 °C.The selectivity coefficients of the polymer for Co(II)/Cd(II),Co(II)/Pb(II),Co(II)/Cu(II),Co(II)/Ni(II)were 2.52,1.34,3.61,4.39,respectively.And there was no significant decrease in adsorption capacity after a test of up to five cycles,demonstrating that the polymer was stable and reusable.(2)Cu(II)-IIP was prepared that Cu(II)as the template ion,methyl acrylic acid(MAA)is selected as monomer,ethylene glycol dimethacrylate(EGDMA)as the cross-linker supported on SBA-15.The results showed that pH=7,the maximum static adsorption capacities of the imprinted polymer was 25.03mg/g at 25 °C.The Cu(II)-IIP has great selectivity for Cu(II).(3)A Cs(I)ion-imprinted polymer was prepared using cesium ion as the template,chitosan(CTS)as functional monomer,and modifying the surface of mesoporous silica SBA-15 by amino,glutaraldehyde via surface imprinting.The polymer was characterized and the results showed that cesium ions were successfully imprinted and the synthesized polymer possessed a highly ordered mesoporous structure.The adsorption capacity of the imprinted polymer for cesium ion was tested in batch experiments.The results showed that pH=5~6,the maximum static adsorption capacities of the imprinted polymer was 36.19 mg/g at 25 °C,The Cs(I)-IIP has great selectivity for Cs(I).