Synthesis And Performance Of Vanillin Molecular Imprinted Solid Phase Extraciton Column

Molecular imprinted polymers (MIPs) as the media of solid phase extractionseparation technology that has a strong selective and simple separation operation, is atechnical means that extract and separate the active ingredients of natural product.In this thesis, molecular imprinting polymers with vanillin as template moleculewere synthesized by suspension polymerization and their absorption performance wereevaluated. The main results are as follow:1. Vanillin molecular imprinted polymer was prepared via suspension polymerizationin toluene solution, using vanillin as template molecular, methacrylic acid as the functionalmonomer, ethylene glycol dimethacrylate as crosslinking agent and azobisisobutyronitrileas initiator.The morphology of the prepared MIPs was observed by field emission scanningelectron microscopy, it showed that the MIPs were good spheroid form and their sizesrange from about dozens of μm to hundreds of μm; the specific surface area wasdeterminated by using NOVA4200e specific surface area analyzer, the results showed thepolymers specific surface area was367.62m~2/g in average.2. The binding properties and selectivity were examined by adsorption kinetics andScatchard analysis. The results of adsorption kinetics of MIPs showed that the adsorptionachieved equilibrium at about60min, and the adsorption rate of vanillin was around84%;Using Scatchard analysis, two dissociation constants for vanillin were calculated,KD1=1079.44μmol/L, Qmax1=180.48μmol/L, the other one was KD2=126.17μmol/L,Qmax2=42.82μmol/L.3. Molecular imprinted polymer adsorption performance by adding a recoveryexperiment.The results showed that the concentration were100mg/L,500mg/L,1000mg/L,that recovery rates of100mg/L to vanillin and5analogues (vanillyl alcohol, vanillic acid,ferulic acid, vanillin and guaiacol) were22.45%,51.08%,67.12%,66.42%,53.98%, therecoveries of500mg/L, respectively to7.26%,21.13%,38.50%,30.39%,19.85%, therecoveries of1000mg/L respectively to5.86%,12.83%,19.29%,19.31%,7.37%. MISPEhas good adsorptivity to vanillic acid, ferulic acid, vanillin and guaiacol, withconcentration increased, the adsorption of MISPE column gradually saturated andadsorptivity to vanillin structural analogues reduced. The determination of breakthrough volume and the maximum adsorption capacity: theresults showed that penetrating volume greater than250mL; maximum adsorption capacityof MISPE column51.39μg/mg.MISPE column was used repeatedly for8times, remained the adsorption rate of99%,so the results showed that the molecularly imprinted polymer has good adsorptivity.4. The fermentation broth obtained by microbial metabolism used guaiacol as rawmaterial was added to the MISPE column for the determination of the adsorption effect ofMIPs to the fementation broth, results showed that the absorption rates of vanillyl alcohol,vanillic acid, ferulic acid, vanillin and guaiacol were85.45%,21.14%,28.23%,83.67%and98.47%, respectively. MISPE column has good adsorptivity to vanillyl alcohol,vanillin and guaiacol.5. Different functional monomers, including acrylic acid, acrylamide,4-vinylpyridine, were used in the preparation of MIPs. The results showed all the prepared MIPsthat the adsorption rate of of vanillic acid and ferulic acid in the fermentation broth were16%~36%, the adsorption rate of vanillin and other structural analogues more than70%,and all the prepared MIPs that the adsorption rate of of vanillyl alcohol in the standardsolution were19%~33%, the adsorption rate of vanillin and other structural analogues over76%, so all the prepared MIPs showed good absorption capacity of vanillin and its4analogues.