Study On Preparation And Performance Of Bacterial Cellulose-graphene Oxide Nanocomposite With Three-dimensional Network Structure

Bacterial cellulose?BC?is a kind of biological nanofiber.Compared with the traditional plant fibers,BC has the larger specific surface area and density and they can intertwine and form an excellent hyperfine three-dimensional network structure.Moreover,BC fiber also has some deficiencies,such as uneven structure,poor mechanical performance as the biological scaffold material,the unconspicuous environmental response and so on.Hence,as a kind of important functional polymer material with many excellent properties,BC-based composites have been widely and deeply studied.Likewise,graphene oxide?GO?has good biocompatibility and is a kind of important ramification of graphene as well as GO is a kind of new-typed two-dimensional carbon nanomaterials with a thickness of approximately monolayer atoms.GO has larger specific surface area and high mechanical strength and its surface or edge contains hydrophilic oxygen-containing functional groups,such as carboxyl,carbonyl,hydroxyl,epoxy group,and so on.These functional groups provides a large number of active points for the functional modification as well as they improve the interaction between GO and polymer group.GO is very suitable for combining with BC due to its excellent properties to compensate for deficiencies of BC.GO nanosheets were introduced into the three-dimensional network structure of BC by stationary in situ co-culture method and dry film adsorption method in this study and then BC/GO nanocomposite was successfully prepared.The structure analysis showed that BC and GO formed the composite with the tight structure and good stability as well as the composite kept the spatial three-dimensional network structure.Afterwards,the form,structure and performance of composite as well as the application in drug loading and heavy metal adsorption were systematically and comprehensively tested and analyzed.The main research contents and conclusions of this paper were as follows.The stationary in situ co-culture and dry film adsorption methods were used to prepare BC/GO nanocomposite with different GO contents and spatial three-dimensional structure.Then,the material characterization methods of SEM,TEM,XRD,FTIR,BET,Raman?mechanical testing were used to systematically analyze the physical,chemical structures and various properties of BC/GO composite.As well as the biomineralization was conducted on the composite prepared by the the two methods,and the various properties of composite with different GO contents after mineralization were characterized.The results showed that the prepared BC/GO composite still kept the spatial three-dimensional network structure of BC and the content of GO nanosheets increased with the increase of GO concentration in the nutrient solution.Moreover,there presented that the mechanical properties and specific surface area of BC/GO were higher than those of BC.After the biomimetic mineralization,there formed the hydroxyapatite?HAp?on both the surfaces of BC fibers and GO.With the increase of GO content,the sediment on the surface of composite increased,which suggested that the composite had excellent biocompatibility.The cytotoxicity test,drug loading property and slow release of the BC/GO composite prepared by stationary in situ co-culture method were carried out.The ibuprofen?IBU?was taken as the model drug to prepare the new-typed slow release drug system with the effect of slow release.In addition,the influence of GO content on the drug loading capacity was mainly investigated by the study on the IBU drug loading and slow release properties of BC/GO composite with different GO contents.The results showed that IBU drug particles covered the whole fiber surface.With the increase of GO content,the drug loading capacity of complexes increased,as well as the coverage density of particles on the BC fibers and GO nanosheets increased and the particles distributed evenly.Finally,the BC/GO composites have good slow release performance of drug by the comparison of slow release performance of drug.The BC/GO composites prepared by static cocultivation method were used for the removal of Cu²⁺,Cd²⁺ and Pb²⁺ in the waste water.The influences of some parameters of pH,reaction time,the quality of the adsorbent and the ion concentration on the adsorption were also studied.The adsorption kinetics fitting was carried out to reveal the characteristics and mechanism of adsorption and,thus providing the theoretical basis for the application of BC/GO in the heavy metal wastewater treatment.The results showed that the adsorption rate of BC/GO for heavy metal ions was greater than that of BC,when the BC and BC/GO with the same quality were added into the solutions with the same kind of heavy metal ions.It is found that the BC/GO-1 composite has the best absorption effect for the three heavy metal ions by the comparison among the BC/GO composites with different GO contents,and the pH value of solution for adsorption was appropriately about 5.5.Thus,the results can make us better understand the adsorption process and provide a kind of new efficient adsorbent for the adsorption of heavy metal ions in waste water.To sum up,the BC/GO composites with excellent performance and spatial three-dimensional network structure were obtained by the static cocultivation and dry film adsorption methods,and this widened the application of BC in the fields of biomedicine and environmental protection.