| Science and technology of polymeric microspheres (particularly natural polymer microspheres) and their dispersions have been developed rapidly for last three decades and the progress seems to be accelerated because the era demands fine materials, mesoscopic science, nanotechnology, etc. An important category of materials among natural polymers is polysaccharides. Among them, cellulose microspheres are the most widely applied to the maximum extent. Cellulose is the most abundant organic compound found on earth. Also, it is a renewable and a major biomass source. But almost all of these products have been prepared from toxic organic solvent or cellulose derivatives, leading it difficult to wash and to eliminate the residual groups, and then limited its bioapplication.In our laboratory, an environmental friendly novel cellulose solvent, namely NaOH/urea aqueous solution has been used. Cellulose could be rapidly dissolved in this solvent at low temperature. The aim of the present work was to investigate the cellulose microspheres from the cellulose solution.The novel development of this work is as follow:1. Regenerated cellulose microspheres (RCM) with diameter ranging from micro to millimeter were prepared successfully by sol-gel transition from the cellulose dope dissolved in NaOH/urea aqueous system at low temperature.2. Novel magnetic cellulose microspheres were prepared successfully by in situ synthesis of Fe3O4 in the cellulose pores as reaction micro-chamber. The Fe3O4/cellulose microspheres were found to exhibite sensitive magnet-inducted delivery and superparamagnetic properties.3. Magnetic cellulose microspheres (MCM) containing y-Fe2O3 were functionalized successfully by using epoxy chloropropane to promote the covalent immobilization of Penicillin G acylase (PGA).4. The magnetic nanoparticles and activated carbon were embedded in cellulose matrix to fabricate a dye sorbent via simple and "green" process.5. An efficient biodegradable heavy metal adsorbent, magnetic cellulose/chitin microspheres consiting of magneticγ-Fe2O3 nanoparticles (MCCM), were succesfully prepared by using sol-gel transition (SGT) method from cellulose and chitin drops in NaOH/urea aqueous solution.Regenerated cellulose microspheres with diameters from micro to millimeter were prepared successfully by sol-gel transition from the cellulose dope dissolved in NaOH/urea aqueous system at low temperature. It was a "green" process for the production of the regenerated cellulose microspheres from renewable raw materials, and the used microspheres were safe and biodegradable. By changing the process parameters, the spherical regenerated cellulose microspheres and beads which possessed the celluloseⅡcrystal structure and with diameters range from 5 um to 1 mm, could be created, and can be used both at laboratory and industrial scale. With a decrease in the dispersant dosage, oil-water ratio and stirring speed, the size of the microspheres increased rapidly. Moreover, the nano-scale pore of the microspheres could be easily regulated by physical dehydration method. The RCM microspheres exhibited good spherical shape, nano-scale pore, as well as better flow properties and adsorption capacity for the dyes. The preparative chromatographic column packed with these cellulose microspheres exhibited good fractionation efficiency and large throughput. Therefore, the RCM microspheres have promising applications as chromatographic packing, biocarrier and biosorbent materials.Novel magnetic cellulose microspheres were prepared successfully by in situ synthesis of Fe3O4 in the cellulose pores as reaction micro-chamber. This was a new, simple, and safe method for the preparation of the magnetic cellulose microspheres having biocompatibility and biodegradability through a "green" pathway. The Fe3O4 nanoparticles were dispersed uniformly in the cellulose matrix, as a result of a strong interaction between Fe3O4 and the cellulose. The micro-chamber in the cellulose microspheres facilitated to retain the shape and size of the Fe3O4 nanoparticles, which play an important role in both the creation of the magnet-induced transference, and the improvement of the targeting delivery and release. The Fe3O4/cellulose microspheres exhibited sensitive magnet-inducted delivery and superparamagnetic properties. Moreover, the magnetic microspheres possessed excellent adsorpton capacity on BSA, and could be described well by the Langmuir isotherms. The pH sensitivity of the BSA adsorption loading and the superparamagnetic properties of the magnetic microspheres will be very important for the bioapplications in the drug targeting delivery and release areas.Magnetic cellulose microspheres were functionalized successfully by using epoxy chloropropane to promote the covalent immobilization of enzyme. Penicillin G acylase was immobilized successfully in the porous structure of the magnetic cellulose microspheres. The existence of the cavity in the cellulose matrix and affinity forces from-OH groups and the Fe2O3 nanoparticles played an important role in the improvement of the enzyme immobilization, leading to the preservation of the structure and nature of biocatalyst. The immobilized PGA exhibited highly effective activity, thermal stability and enhanced tolerance to pH variations, as well as good reusability. Moreover, the cellulose magnetic microspheres loaded with PGA could be conveniently and easily separated from reaction solution, leading to recovery of the catalysts. The new immobilization carriers prepared from safe, low cost and biocompatible cellulose will have wide applications in the development of biocatalysts.Magnemite (y-Fe2O3) nanoparticles of about 10 nm were prepared in a submerged circulation impinging stream reactor. The magnetic nanoparticles and activated carbon were embedded in cellulose matrix to fabricate a sorbent via simple and "green" process. Two dyes including positively charged methylene blue (MB) and negatively charged methyl orange (MO) as models of organic dyes were adsorbed effectively by the MCB-AC beads. The Fe2O3 nanoparticles and AC in the MCB-AC could play an important role in both the formation of spherical shape beads and the improvement of the adsorption capacity. The MCB-AC beads exhibited high adsorption capacity for the two dyes, and could more strongly adsorb MO. The adsorption kinetics was fast with 180 min to reach equilibrium time, and the kinetic data were well fitted by a pseudo-second-order model. Furthermore, the sorbent could be regenerated and used repeatedly. The magnetic properties of the beads allow their separation from the effluent by applying a magnetic field, leading to the development of a clean and safe process for water pollution remedy. This work provided a new pathway for the preparation of the MCB-AC beads including theγ-Fe2O3 nanoparticles and AC, and this process is promising on a large scale production.Magnetic chitin/cellulose microspheres were successfully prepared by coagulating a blend of cellulose, chitin andγ-Fe2O3 nanoparticles in 7wt% NaOH/12wt% urea aqueous solution by sol-gel transition. This adsorbent has a porous structure, larger surface area and the affinity for heavy metal ions. The magnetic microspheres possessed excellent adsorpton capacity on heavy metal ions (Pb2+,Cd2+ and Cu2+). The adsorption kinetics was fast with 3-5h to reach equilibrium, and the kinetic data were well fitted by a pseudo-second-order model. The magnetic properties of the beads allow their separation from the effluent by applying a magnetic field, leading to the development of a clean and safe process for water pollution remediation. Moreover, the microspheres could be regenerated by treating with 1 mol/L HC1 aqueous solution. Therefore, we developed new environment-friendly microspheres prepared by a simple process for removal and recovery of heavy metals.This thesis is comprised of studies on pure cellulose microspheres and functionalized microspheres with different particle size created from cellulose in NaOH/urea aqueous solution by different method, such as sol-gel transition, surface modification, and physical and chemical blending. A series of scientific and technological problems were resolved. Through these studies, we developed a low-cost, nontoxic and "green" process for fabrication of cellulose microspheres materials on a large scale production. Therefore, we anticipate were great scientific significance and prospects for application of these materials which are used for out country and play a major role for a sustainable development.
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