Preparation And Application Of Silver Ion Cross-linked Natural Polysaccharide Macromolecules Gel Systems

Natural polysaccharide macromolecules such as sodium alginate and carboxymethyl cellulose have a wide range of applications in the fields of environmental governance,medicine and chemical engineering,due to their good biocompatibility and biodegradability.In this thesis,we selected several natural polysaccharide macromolecules to study their cross-linking effect with monovalent Ag~+,the application of Ag~+cross-linked gel beads as carrier materials in drug release and photocatalytic degradation of pollutants.The main parts are as follows:1.A series of natural polysaccharide macromolecules were selected,and their cross-linking performance with monovalent Ag~+was explored.The natural polysaccharide macromolecules that can be crosslinked with Ag~+to form gel beads were screened out,and their ability to crosslink with Ag~+to form gel beads was investigated,including the degree of change in the quality of gel beads over time during the crosslinking process.The stabilities of gel beads and Ag~+in the gel beads were explored by various methods.In addition,the interaction between polysaccharide molecules and Ag~+was explored by infrared spectroscopy.2.A gel bead with interpenetrating network structure(IPN)was prepared by a stepwise cross-linking method,in which a sodium alginate/acrylamide mixed solution was dropped into an Ag~+solution,followed by physical cross-linking of sodium alginate with Ag~+and chemical cross-linking of acrylamide polymerization.Then,ketoprofen was loaded into gel beads by dispersion technology to study the sustained-release behavior of the drug delivery system.The composition,structure and stability of the gel beads were analyzed by various analytical methods.The antibacterial properties of the gel beads were tested,and the effects of the ratio of sodium alginate/acrylamide,polymer concentration,and Ag~+concentration on the swelling and drug release behavior of the gel beads were explored.3.CN/GO loaded carrageenan/sodium alginate composite gel beads were prepared under Ag~+crosslinkage.The Ag~+ions were reduced in situ to Ag~0 under ultraviolet light to finally obtain the Ag/CN/GO-DB photocatalyst after freeze-drying treatment.Its chemical composition and microstructure were characterized by various means.Ag/CN/GO-DB was used for photocatalytic degradation of methylene blue to study the degradation kinetic characteristics of methylene.The effect of CN/GO loading on the catalytic activity was investigated.Based on the results above,the mechanism of photocatalytic degradation of methylene blue was proposed.