Adsorption And Separation Research Of Apple Polyphenols Based On Aminated Magnetic Chitosan Microsphere

The content of polyphenols was extremely rich in apples.Apple polyphenols had many functional activities,such as antioxidation,anticancer,anticarious,antiallergic,inhibition the growth of microbes,etc.So apple polyphenols were paid more and more attentions and became a research focus for scholars both domestic and abroad.Apple pomace was the solid waste in the production of apple juice and wine,which was rich in extractive polyphenols.The content of polyphenols was much higher than pulp.So turning waste into wealth and extraction and separation of the polyphenols had very big potential value and economic interests.In this paper,the initial use of magnetic materials for adsorption and separation of polyphenols in Apple Pomace was discussed.The magnetic material was characterized.The adsorption condition was optimized,and the best adsorption process was determined.Kinetics and thermodynamics of the adsorption process were conducted.And the desorption of apple polyphenols from magnetic materials was discussed.The aim of this paper was to provide a new way for extraction and separation of apple polyphenols and establish theoretical basis for extraction process of apple polyphenols by magnetic materials.The results of this study were as follows:1.Aminated magnetic chitosan microspheres had the best adsorption effect for apple polyphenols among four chosen magnetic materials.Using single-factor experiment was applied to get the process parameters:2mL 25%volume fraction of glutaraldehyde,5mL/g epichlorohydrin and 3mL/g ethylenediamine and saturated adsorption ratio was 81.94%.2.Fe3O4 particles were synthesized by coprecipitation,.Magnetic chitosan microspheres were prepared through inverse suspension cross-linking and was amino modified.Amino content was increased significantly to 4.56 mmol/g after amino modified.Fe3O4 particles was characterized by tuansmission electron microscopy,laser particle size analyzer and Super paramagnetic.Aminated magnetic chitosan microsphere was characterized by scanning electron microscopy and laser particle size analyzer.Fe3O4 particles was nanometer level,super paramagnetic,with poor dispersivity and irregular shape.The prepared aminated magnetic chitosan microspheres was micron,spherical,with good dispersion and smooth surface.3.The single-factor experiment and response surface method was applied to optimize the adsorption factors of apple polyphenols.Process parameters of separation of apple polyphenols by aminated magnetic chitosan microspheres have significant effect on adsorption rate of apple polyphenols.The influence order of factors is:usage of microspheres>shaker speed>adsorption temperature.The optimum adsorption conditions of apple polyphenols by aminated magnetic chitosan microspheres were as follows:usage of microspheres0.249 g/mL,adsorption temperature 44.8 ℃,shaker speed 127 r/min,and under this condition,the adsorption rate could reached to 83.10%.4.The pseudo-first-order kinetics model,the pseudo-second-order kinetics model,Elovich equation and pore diffusion equation were used to fit the adsorption kinetics process.Three isothermal adsorption models(Langmuir,Freundlich and Temkin)were used to analysis adsorption thermodynamics properties.The results showed that adsorption kinetics process conformed to the pseudo-second-order kinetics model.As adsorption temperature increased,adsorption rate constant,initial adsorption rate and equilibrium adsorption content tended to increase.Adsorption thermodynamics conformed to Freundlich isothermal adsorption model.The results of thermodynamic parameters are ΔG<0,ΔH>0 and AS>0,which indicated that adsorption of apple polyphenols onto aminated magnetic chitosan microspheres was a spontaneous and exothermic process along with entropy increase.5.The desorption research was conducted using three solution,which was NaOH solution,ethanol solution,NaCl solution and their mixtures.NaOH solution had the best elution effect.Single-factor experiment was applied to get the best elution process parameters:concentration of NaOH solution 4%,elution time 50min,elution temperature 20℃,shaker speed 150 r/min,and under this condition,the desorption rate could reached to 78.73%.