Chitosan Modification And Design Of Chitosan-Based Membrane Chromatography

In view of growing public health and environmental awareness accompanied by an increasing number of ever stricter environmental regulations on discharged wastes, attention has been focused on the use of natural polymers from renewable resources as alternative to synthetic polymers. Chitosan (CS), derived from chitin that is the main structural component of the invertebrate exoskeleton and the fungal cell wall, is an abundant natural polymeric resource. Chitosan is famous for its good filming in the field, as well as good chelating properties and mechanical properties for separation the solute from aqueous solute.The advantage ofmembrane chromatography, which combines the advantages both chromatography technology and membrane separation technology,was fast, high-efficiency in overcoming mass transfer limitation, high-selective properties, easy-amplifiance. Membrane materials is a key point for preparation for membrane chromatography and obtaining a high separation efficiency. The thesis mainly focus on preparation different type membrane chromatography for fraction protein from the mixture system and separation the pollute from waste-water,which based on chitosan and the other organic/inorganic materials composite.In chapterl,we give a brief introduction in this field:the concept, history, research progress and proposed questions in the chitosan modification and preparation of the membrane chromatography.In chapterII,We successfully used macroporous CS/CMCS blend membrane as the matrix to set up a membrane chromatography for protein adsorption and separation. We selected lysozyme as model protein and investigated the dynamic adsorption property of lysozyme on the CS/CMCS membrane chromatography extensively by varying the pore size of the membrane, the flow rate and the initial concentration of feed solution as well as the layer of membrane in membrane stack. The results showed that the suitable pore size, low flow rate and high initial lysozyme concentration was favorable to achieve a high dynamic adsorption capacity. Although the increase of layer of the membrane also helped to increase the dynamic adsorption capacity, it was not obvious as expected that may due to the imperfect design of the apparatus. The CS/CMCS membrane chromatography showed good repeatability and reusability with the desorption efficiency of-90%, and it separated lysozyme and ovalbumin from their binary mixture successfully. All these imply that such a natural chitosan-based membrane chromatography may have great potential on the bioseparation field in the future, for instance separating lysozyme from the egg white.In chapter Ⅲ, we reported a simple method is developed to assemble orderedmesoporous carbon materials into robust CS membraneswith tunable thickness, porosity and content of carbon component.The composite membranes hold three-dimensional macropores,which provide fast and high-throughput filtration offlowing water streams. The anchored mesoporous carbon particlescan provide a high interface and a high density of adsorptionactive sites for capturing targeted molecules. Such ahierarchical CS/FDU-15model membranes possess high staticadsorption capacity and fast adsorption kinetics toward themodel dye fuchsin and phenolmolecules. CS/FDU-15membrane chromatography shows a promisingdynamic adsorption property toward thefuchsin and phenol fromflowing water streams. Moreover, the membrane sorbents canbe easily regenerated with stable cyclic performance and thepre-trapped dye molecules can be also recovered with a highand stable efficiency.In chapter Ⅳ,we prepared another CS/Fe@Cmembrane chromatography based on the chapterlll. we investigated the adsorption properties with the NaAsO2as a modal pollute in simulating the waste-water. The CS/Fe@Ccompositemembrane hold three-dimensional macropores,which provide fast and high-throughput filtration offlowing water streams. Such ahierarchical CS/Fe@C model membranes possess high staticadsorption capacity and fast adsorption kinetics toward themodel inorganic compound NaAsP2. By assembling the hierarchicalmembranes into an adsorption column, it shows a promisingdynamic adsorption property toward the NaAsO2fromflowing water streams. Moreover, the membrane sorbents canbe easily regenerated with stable cyclic performance with a highand stable efficiency. Finally, the method for fabricating themembranes is quite simple and easy for processing and it maypave the way for the development of a series of other hierarchicalblend membranes for water contamination.In chapter V,a multistep synthesis of a polysaccharide/polypeptide hybrid material is reported in this paper. We first modified CS to Tr-CS in order to make it soluble in specific organic solvent and protect the6-OH group. Then, we successfully initiated the ROP of y-benzyl-L-glutamate NCA onto Tr-CS. Finally, we obtained the target product CS-g-PGA copolymer by deprotecting the corresponding protected groups. After we successfully synthesized CS-g-PGA copolymer, we studied the self-assembly behavior of such a hybrid material with amphiphilic nature. Spherical nanoparticles were obtained after the dialysis of CS-g-PGA DMSO solution against de-ionized water. The size of CS-g-PGA nanoparticles was found to be controlled by the feed ratio of Tr-CS to y-benzyl-L-glutamate NCA. We believe such a bio-based polysaccharide/polypeptide hybrid nanoparticles with the controllable size may have great potential in biomedical fields, such as drug delivery systems.In the last part the charpter VI,we summary and prospect of our research work. Our research work mainly focus on the design of the membrane chromatography. We successfully designed and finished three chitosan and other materials composite membranes chromatography, that is CS/CMCS blend membrane chromatography,CS/FDU-15membrane chromatography, CS/Fe@Cmembrane chromatography, and prepared a polysaccharide/polypeptide hybrid material, which we investigated the self-assembly behavior of such a hybrid material with amphiphilic nature.