Study On The Preparation And Recognition Properties Of Menthyl Acetate Molecularly Imprinted Ceramic Balls

Menthyl acetate is a natural spice ingredient that presents in peppermintoil. Its smell is like a refreshing smell of mint and rose. Menthyl acetate is sofavored by the perfumer because of its softer smell than menthol and it has noexisting volatile, strong irritant defects. There are complex compositions inpeppermint oil and in which, some substances are similar with menthylacetate’s nature and some are similar with its structure. So at present thereisn’t a mature technology for natural menthyl acetate’s separation andpurification. In this study, the molecular imprinting technique was applied tothe separation and purification of the spice ingredients and the menthyl acetatemolecularly imprinted ceramic balls were successfully prepared. Themolecularly imprinted ceramic balls were used in menthyl acetate adsorptionseparation from peppermint oil and supercritical fluid extraction technologywas used for desorption of the target molecular from imprinted ceramic balls.Main specific works are as follows:1.Molecularly imprinted polymers was prepared using menthyl acetate asthe template molecule, acrylamide as functional monomer, ethylene glycoldimethyl as the cross linker by precipitation polymerization method and thenatural polymer deposition formed on the surface of porous support mediumceramic ball (CBs) to completing the molecularly imprinted ceramic balls(MICBs). The influence of the reaction conditions to the generation amount ofthe molecularly imprinted polymer and the amounts of the reactants to theMICBs adsorption were investigated. The elution and adsorption kinetics ofthe template molecules in the molecularly imprinted ceramic balls werecarried out. The analysis results showed that: the optimal conditions of thepreparation process were aerating with nitrogen to oxygen removal10min,reaction temperature50℃and the reaction time48h. The best ratio of theamount of the materials added was the template, monomer and cross linkermolar ratio of1:4:16. The eluting time and adsorption time of the templatemolecules in imprinted ceramic balls were respectively24h and32h. 2. A scanning electron microscope (SEM) was used to analyze thesurface morphology of the molecularly imprinted ceramic balls to prove thatthe molecularly imprinted polymers were deposited on the surface of thesupporting medium ceramic balls. The presence of the interaction forcebetween template molecule menthyl acetate and functional groups was provedby Fourier transform infrared spectroscopy (FTIR). The binding properties ofthe MICBs was studied using the static adsorption curve and the Scatchardcurve and its binding equilibrium constant (KD) and apparent maximumbinding capacity (Qmax) were respectively1.8mmol/L,3.2μmol/g which werecalculated by the fitting equation. The selected specific selectivity of themolecularly imprinted ceramic balls was tested by choosing menthol whosecontent is high in peppermint oil as another separate object, and the resultsshowed that the separation factor (α) was1.42and its imprinting efficiency (β)was1.34.3. To explore the selective adsorption, imprinted ceramic balls wereapplied to the menthyl acetate adsorption in peppermint oil. The resultsshowed that after molecularly imprinted ceramic balls’ adsorption, thementhyl acetate relative percentage of the eluent increased to14%which rawmaterial peppermint oil just had6%menthyl acetate and the percentage was96%which raw material peppermint oil had86%menthyl acetate. Theinfluences of pressure, temperature and time on the molecularly imprintedceramic balls desorption of the target substance were investigated in thesupercritical process. Experimental results showed that the target molecules inceramic balls could be desorbed completely under the supercritical extractionpressure10MPa, temperature35℃for20min, which was equivalent withthe24h solvent elution effect.