Preparation And Application Research Of Magnetic Porous Cellulose Microspheres

Combined with the advantages of the cellulose and magnetic materials, thecellulose-based magnetic composite microspheres were synthesized by using cellulose as thematrix, and Fe3O4nanoparticles as the reinforcing phase, which had potential applications inthe field of cell separation, drug-carried and biocatalysis owing to its unique properties suchas biodegradation, biocompatibility, and magnetic responsibility. Therefore,it has importantsignificance to explore novel cellulose microsphere materials and their applications. In thiswork, based on the cellulose as the basic raw material, cellulose-based magnetic compositemicrospheres were synthesized by several different methods. The composite microsphereswere characterized by scanning electron microscopy, transmission electron microscopy,Fourier transform infrared spectroscopy, X-ray diffraction, and vibrating-samplemagnetometer. Subsequently, applications in the field of biocatalysis and adsorption of dyeand heavy metal ions were studied.1. Magnetic cellulose microspheres were prepared by sol-gel transition method usingionic liquids as solvent for the adsorption of heavy metal ions. The microspheres were studiedby SEM, FTIR, XRD, and VSM. Subsequelty, the adsorption of Cu(II), Pb(II), Cr(III), Ni(II),Cd(II) were investigated systematically with varried parameters such as pH, contact time, andinitial concentration. Results revealed that the Fe3O4nanoparticles were spherical particleswith mean size of10-15nm. The microshpheres were examined to be with the mean size of10μm and their sizes decreased with the increase of dispersant dose, oil-water phase ratio andstirring speed. The maximum adsorption of Cu(II), Pb(II), Cd(II),Ni(II), Cr(III) reached12.1mg/g,36.2mg/g,10.9mg/g,27mg/g and7.7mg/g, respectively.2. Novel nanoporous magnetic cellulose-chitosan composite microspheres (NMCMs)were prepared by sol-gel transition method using ionic liquids as solvent for the sorption ofCu(II). The composite microspheres were studied by SEM, FTIR, TGA, XRD, and VSM.Subsequelty, the adsorption of Cu(II) to NMCMs was investigated systematically with varriedparameters such as pH, contact time, and initial concentration. Results revealed that NMCMsexhibited irregular spheres structure with the mean diameter of about10μm, the pore size ofNMCMs ranged from10to200nm with peak value of the pore diameter of80nm. The SBETand pore volume of the dry NMCMs are102.3m2/g and4.1cm3/g, respectively. NMCMsexhibited efficient adsorption capacity of Cu(II) from aqueous solution, due to their favorablechelating groups in structure. The adsorption process was best described by a pseudo-second-order kinetic model, while isotherm modeling revealed that the Langmuirequation better describe the adsorption of Cu(II) on NMCMs as compared to Freundlichmodel. Moreover, the loaded NMCMs can be easily regenerated with HCl and reusedrepeatedly for Cu(II) adsorption up to five cycles. The environmental friendly microsphereswere expected to be a promising candidate for future practical use in heavy metal ionsremoval.3. NMCMs were studied by TG analysis. Subsequently, NMCMs were functionalizedsuccessfully by using glutaradehyde to immobilize Laccase. Results revealed that NMCMsexhibited an onset of weight loss at around230oC. The activity recovery of immobilizedlaccase reached80.6%under the following conditions: activation time was8h,glutaraldehyde concentration was6%; enzyme concentration was6mg/mL, immobilizationtime was4h. Compared with free laccase, the pH, thermal, operational and storage stabilitiesof the immobilized laccase were improved. The NMCMs immoblized laecase may adsorb andcatalyse oxidation of2,4-dichloropenol，the removal efficiency of2,4-dichloropenol in waterreached86%after8h. Furthermore, the immobilized laccase retained67%removal efficiencyafter6consecutive operations.4. Novel magnetic porous cellulose triacetate microspheres were prepared successfullyby in situ synthesis of Fe3O4in the cellulose triacetate pores as microreactor. The cellulosetriacetate was prepared via reacting of a mixture of acetic anhydride and acetic acidcontaining sulfuric acid as catalyst with ramie fiber obtained from a biomass of ramie.Characterization results revealed that the cellulose triacetate microspheres exhibited anaverage diameter of18μm, mean pore diameter of500nm and SBETof102.3m2/g,respectively. Application of the novel microspheres as an adsorbent for removing DisperseRed FB dye in water was investigated. The maximum adsorption of Disperse Red FB reached34.7mg/g. The adsorption process was best described by a pseudo-second-order kineticmodel and Langmuir equation.