Preparations And Applications Of Imprinted Functionalized Ordered Mesoporous Silica Materials

Ordered mosoporous materials are the novel porous nano materials with regularly arranged pore canals of adjustable pore size,large specific surface area and fine thermal stability.In recent years,numerous studies have shown that functionalization can broaden the fields of application of mosoporous silica.Molecular(ion)imprinting technology(MIT),originated from immunology,is an emerging technology with specific recognition capability,which combines polymer chemistry,material science,chemical engineering and biochemistry.Integrating ordered mosoporous materials and MIT mentioned above,mosoporous materials and molecular(ion)imprinting polymers with great features have applied in the fields of adsorbents and sensors.Molecular(ion)imprinting mosoporous silica(MIMS or IIMS)prepared by one-step co-condensation contributes to explosion of the recognition sites in the pore walls area and capture of targets.Based on the merits of MIMS,we designed and synthesized three kinds of ordered MIMS or IIMS for adsorption application of trivalent chromium,hexavalent chromium and nonyl phenol.1.On the basis of the structure of SBA-15,Cr(III)ion imprinted mesoporous silica(Cr(III)IMS)was synthesized and used as an excellent adsorbent to adsorb Cr(III)ions in acid effluents.Various characterization methods were used for analysis of properties and performance of resultant materials.The X-ray diffraction(XRD)and transmission electron microscopy(TEM)analysis indicated the highly ordered hexagonal p6mm structure.The Brunauer-Emmett-Teller(BET)surface area was greatly large(856 m~2/g).Cr(III)IMS was then applied in adsorption experiments.The saturated adsorption capacity of Cr(III)IMS towards Cr(III)ions reached up to 63 mg/g at pH 4.5.At a concentration of 200 mg/L,the adsorption of Cr(III)ions reached equilibrium rapidly within 5 min at pH 4.5.The imprinting factor was up to 4.03 at pH 3.0.In selective adsorption experiments,the relative selectivity coefficient of Cr(III)IMS towards Cr(III)ions was up to 4.00,remarkably higher than other ions(1.14 to 1.73).After eight adsorption-regeneration cycles,the adsorption efficiency of CrIMS still reached above 94.1%.The Cr(III)IMS could effectively remove the Cr(III)ions below the discharge standard(0.1 mg/L)of China in the wasteful water sample treatment.2.Different with Cr(III),Cr(VI)exists as an anion and its toxicity to envioroment is much higher than Cr(III).Combined with the structure of MCM-41 mesoporous silica,Cr(VI)imprinted mesoporous silica(Cr(VI)IMS)was synthesized by one-step method.Three types of Cr(VI)IMS have been prepared by three functional monomers which contain amino(imino group),quaternary ammonium group or imidazolyl.The chemical groups,porosity and highly ordered morphology of three types of Cr(VI)IMS were characterized by Fourier transform infrared spectroscopy(FTIR),solid state nuclear magnetic resonance(NMR),BET method,XRD,TEM and SEM,respectively.The BET surface areas were 1102 m~2/g,958 m~2/g and1054 m~2/g.The saturated adsorption capacity of Cr(VI)IMS towards Cr(VI)ions reached up to 40.8 mg/g,52.3 mg/g and 45.6 mg/g at pH 3.0.At a concentration of 200 mg/L,the adsorption of Cr(VI)ions reached equilibrium rapidly within 7 min,10 min and 10 min,respectively.The relative selectivity coefficients of Cr(VI)IMS were 2.90,3.36 and 2.56,higher than other anions(below 1.5).The adsorption experiments of adsorption-regeneration of 8 cycles and 5 different batches showed good repetition and reproduction of Cr(VI)IMS.Treated by optimized amount of Cr(VI)IMS,the concentration of Cr(VI)ions those samples were below the discharge standard of China.3.By using nonyl phenol as target,combined molecular imprinted technology with mesoporous silica materials(MCM-41),ordered nonyl phenol imprinted mesoporous silica(NPIMS)was synthesized.NPIMS was prepared with functional monomer N-Phenyl-3-aminopropyltrimethoxysilane(NP-3-APTMOS)by co-condensation method.The functional groups,porosity and highly ordered morphology of NPIMS were characterized by FTIR,solid state NMR,BET method,XRD,TEM and SEM,respectively.The BET surface area was 991 m~2/g.After optimization,NPIMS showed the best specific adsorption capacityto nonyl phenol,when the ratio of template and functional monomer was 1:4.The adsorption capacity was 56.4 mg/g and the impirinting factor was 3.22.At a high concentration of 300mg/L,the adsorption of nonyl phenol reached equilibrium within 10 min.NPIMS displayed much higher adsorption capacity to nonyl phenolthan other analogues.The relative selectivity coefficient was 3.06 which was better than other materials.NPIMS was used as stationary phase of solid phase exaction(SPE)for exaction to nonyl phenol from extracting solution of textile samples.NPIMS was an excellent novel SPE material and displayed selective adsorption and great enrichment ability to nonyl phenol in complex samples in pretreatment.