Adsorption Of Chlorogenic Acid In Mulberry Leaves By Ionic Liquid Based Cellulose Microspheres

Mulberry leaf,as a traditional medicine for both medicine and food,is rich in polyphenols,alkaloids,polysaccharides and other active ingredients,with antioxidant,hypoglycemic,anti-tumor,antibacterial effects.Mulberry leaf is a kind of high economic value of resource,has been widely used in feed of mulberry silkworm,food,medical treatment and other fields.In this study,five polyphenols and two alkaloids were successfully determined from mulberry leaves by establishing liquid chromatography-mass spectrometry methods for qualitative and quantitative detection.Ionic liquids groups modified 3D structure cellulose microspheres(CMs)were successfully prepared.FTIR,XRD,XPS and other characterization methods were used to prove the successful synthesis of ionic liquids modified cellulose microspheres(CMs-ILs).Finally,the adsorption process and adsorption mechanism of chlorogenic acid(CGA)from mulberry leaves were studied with CMs-ILs as adsorbent.Specific research results are as follows:1.Firstly,five kinds of polyphenols in mulberry leaves and two kinds of alkaloids were analyzed by mass spectrometry,respectively.After establishing HPLC-PDA-MS/MS and HILIC-MS/MS method,five polyphenols in mulberry leaves(chlorogenic acid,quercetin,isoquercitrin,rutin,kaempferide)and two alkaloids(DNJ and fagomine)were detected qualitatively and quantitatively,and the stability and feasibility of the test method were verified through the intraday day repeatability.Finally,it was found that the chlorogenic acid content was the highest in mulberry leaf samples,which was11.71±0.05 mg/g.Due to low price and large output,mulberry leaves can be used as a potential chlorogenic acid resource.2.Cellulose microspheres with 3D porous structure were prepared by non-derivatization,low temperature dissolution and sol-gel transformation method.CMs1-CMs7 were obtained by co-precipitation of nano-alumina,silanization,and finally modification of seven different ionic liquid groups.It can be observed from SEM images that CMs-ILs have good spherical morphology and 3D porous structures.The particle size of the microspheres is mostly distributed around 200?m and the specific surface area is 31.473 m~2/g.The results of element distribution mapping,FTIR and XPS all indicated the successful modification of ionic liquid groups.XRD analysis showed that the crystal structure changed from crystalline cellulose I to crystalline cellulose II during the process of converting cotton linter pulp into cellulose microspheres.Meanwhile,its crystallinity index decreased from 84.14%to 48.76%.3.The static adsorption experiments of chlorogenic acid in mulberry leaves were carried out by using CMs1-CMs7 and three commonly used macroporous adsorption resins(D101,NKA-9,AB-8)as adsorbents.It was found that the adsorption capacity of seven CMs-ILs was almost three times that of resin(30 mg/g).CMs3 has the highest adsorption capacity which is 103.6 mg/g.In the following experiments,adsorption thermodynamics and adsorption kinetics of CGA in mulberry leaves were studied with CMs3 as adsorbent.The results showed that the adsorption of CMs3 on CGA was exothermic.In terms of adsorption kinetics,CMs3 reached saturation adsorption in about 40 minutes,while it took about 150 minutes for the resin to adsorption equilibrium,indicating that CMs3 was superior to the resin in adsorption capacity and adsorption rate.Compared with other materials reported in other literatures,CMs3 also shows excellent adsorption effect.In terms of purification effect,after CMs3 treatment,the purity of chlorogenic acid increased from 0.70±0.01%to 6.96±1.26%,almost 10times more than it was before the adsorption.The results of the reuse experiment showed that the adsorption capacity of CMs3 was still 88.7±1.82%after five times of reuse,indicating that it had a good reuse capacity.4.From the perspective of chemical combination of CGA and CMs3,the complexation energies between seven ionic liquids and CGA were obtained by quantitative calculation.The results were consistent with the static adsorption results.By means of density functional theory,the combination of CMs-ILs and CGA is simulated,and it is found that they are mainly combined by?-?stacking,hydrogen bonding and van der Waals electrostatic attraction,among which the?-?stacking plays the most important role.By comparing the quantitative calculation of infrared simulation with FTIR data,it was found that CMs3 absorbed CGA successfully.To explain the reason for the rapid adsorption of CMs3,this paper firstly proved the super-hydrophilic property of CMs3 from the point of hydrophilic property of the material through the contact angle test.Thus,CGA can rapidly diffuse in the internal channels of CMs3,thus accelerating the mass transfer rate and achieving rapid adsorption.