Study On Metal Organic Framework ZIF-8 As Carrier Material For Fragrance

Fragrance as a functional additive has limited application in industry due to its poor stability,easy deterioration and volatilization.In recent years,the technology of encapsulating fragrances has been continuously developed.At present,the main materials for encapsulating fragrances include microcapsules,biomolecular materials,and porous materials.As a member of the porous material,ZIF-8 has the advantages of high specific surface area,cage structure,stable chemical properties,good biocompatibility,simple preparation process and mild preparation conditions compared with other materials.It is an ideal material for loading fragrance.This article carries out research on the method of loading fragrance and the release of aroma,so as to propose a new method to improve the stability of fragrance and prolong its shelf life.Acetophenone,phenylethanol,menthol and damascenone were successfully loaded in ZIF-8.The fragrance exists on the surface and pores of ZIF-8,and the addition of fragrance will not change the lattice structure of ZIF-8.The load of different fragrances on ZIF-8 was successfully achieved by coprecipitation.This method is universal and can be applied to most small fragrance molecules with negative Zeta potential.Through single factor experiments,it was verified that the dosage of zinc nitrate hexahydrate was positively correlated with the entrapment rate,and the dosage of 2-methylimidazole and acetophenone was negatively correlated with the entrapment rate.In order to optimize the loading effect of fragrance,based on the single factor experiment,a model for predicting the entrapment rate was established by response surface methodology.The results show that when the addition of zinc nitrate hexahydrate and 2-methylimidazole is 0.425 g and 0.094 g respectively,and the addition of acetophenone was 50.330 μL,the highest entrapment rate was 50.547%.The retention rate and release time of acetophenone were fitted by Avrami equation.The results showed that the release mechanism of acetophenone was first-order release kinetics at 4℃;When the temperature is 25℃ and 50 ℃,the release mechanism of acetophenone is a combination of diffusion limited kinetics and first-order release kinetics.Under the environmental condition of pH 5,the release mechanism of acetophenone is first-order release kinetics;when pH is 7 and 9,the release mechanism of acetophenone is a combination of diffusion limited kinetics and first-order release kinetics.When the environment is acidic,the framework of ZIF-8 will collapse and acetophenone will be released rapidly.