Preparation And Application Of Magnetic Cellulose Materials

In this work, cellulose was dissolved to make regenerated cellulose films and regeneratedcellulose microspheres in LiOH/urea solvent. Magnetic cellulose films and magneticcellulose microspheres were prepared successfully in the cellulose pores as reactionmicro-chamber by using in-situ synthesis method. And further studies were carried out bylearning its structure and performance. The research contents are as follows:1、Preparation of magnetic cellulose aerogels and research of structure and propertiesNanostructured cellulose nanofibrils can form ductile or tough networks that are suitabletemplates for the creation of materials with other functional properties. In this work, a facileroute has been developed for the preparation of magnetic hybrid cellulose aero-gels. Thepreparation process followed by two steps: firstly, preparation of cellulose hydrogel filmsfrom LiOH/urea solvent, then in-situ synthesis of CoFe2O4nanoparticles in the porousstructured cellulose scaffolds. After being freeze-dried, CoFe2O4/cellulose magnetic aero-gelswere obtained. The structure and properties of the magnetic cellulose films were studied bySEM, TEM, XRD, BET, TG and mechanical stretch. The porosity of the composite aerogelsranged from78to52%with pore sizes distribution in a few tens of nanometers. The internalspecific surface area was around300–320m2/g. The hybrid aero-gels showedsuper-paramagnetic behaviors, improved mechanical properties. Unlike solvent-swollen gelsand ferrogels, the magnetic composite aerogels were lightweight, flexibility, high porosity andspecific surface area.2、Preparation and structure of magnetic cellulose microspheresRegenerated cellulose microspheres were successfully prepared by using the sol-geltransition method from cellulose drops in7wt%LiOH/12wt%urea aqueous solution.Subsequently, novel magnetic cellulose microspheres were fabricated by in-situ synthesis ofCoFe2O4nanoparticles into the cellulose pores. The structure and morphology of regeneratedcellulose microspheres and magnetic cellulose microspheres were analyzed using SEM, XRD,BET, and TG. The effects of the hydrophilic-lipophilic balance (HLB) of the emulsifiers,emulsification time, emulsification temperature and concentration of cellulose solution werestudied respectively. The result showed that the size distribution of regenerated cellulosemicrospheres was moderate when emulsifying3hours in15℃under the conditions of HLB7with SP-80/TW-80as emulsifier and4.3%cellulose solution; and CoFe2O4nanoparticleswere dispersed uniformly and immobilized in the matrix of the cellulose microspheres, theporosity of the magnetic cellulose microspheres ranged from96.92to95.23%, the densitywas in the range of11.3-15.7mg/cm3. The hybrid aerogels showed superparamagneticbehaviors and sensitive magnetic responsiveness.3、 Magnetic cellulose microspheres immobilized lipase and research of its catalyticperformanceThe introduction of N-[3-(Trimethoxysilyl)propyl]ethylenediamine (AEAPS) intomagnetic cellulose microspheres was carried out using a silane coupling technique, leading tothe improvement of hydrophobicity. Immobilization of lipase enzymes onto the AEAPS-modified magnetic cellulose microspheres was then accomplished, and the synthesisof1-phenylethylacetate by nonaqueous transesterification of1-phenylethanol and vinylacetate was studied. The immobilized lipase showed high catalytic activity, selectivity andreusability. Thus, the immobilized enzyme is expected to offer a green catalytic material forthe effective production of useful chemicals.In summary, two kinds of magnetic cellulose materials were prepared by using cellulosenanofibrils networks as templates. And due to the improvement of hydrophobicity, theAEAPS-modified magnetic cellulose microspheres is expected to offer a green catalyticmaterial for immobilization of lipase.