Preparation And Study On Dye Adsorption Ability Of Modified Magnetic Chitosan Composites

With the rapid population growth and the impact of industrialization,the problem of water pollution has also become more complicated and more harmful.Due to the large demand for dyestuffs and the large demand for related products,the dye wastewater generated by the dyeing-related process has become one of the main sources of water environmental pollution.Based on the background of the appeal,the effective treatment and removal of dye molecules in environmental water bodies has important practical significance for the protection of water resources and the prevention and control of printing and dyeing wastewater pollution.In this paper,chitosan is used as the base material,and two diisocyanate crosslinking agents are used to modify chitosan to improve its adsorption performance for dyes.In order to increase its recyclability,Fe₃O₄ is added as a modification.The introduction of magnetism into the material is convenient for recycling.The main research contents are as follows:(1)Using hexamethylene diisocyanate(HDI)as a cross-linking agent to prepare modified chitosan HDI-CS,comprehensive analysis of the composite material using a variety of characterization methods,proved the success of the cross-linking modification method.Subsequently,the adsorption performance of the material for dyes was explored through adsorption experiments.Under the experimental conditions of this thesis,it was found that the maximum adsorption capacity of HDI-CS for methyl orange and methylene blue was 108.52 mg/g and 99.73 mg/g,respectively.(2)Using diphenylmethane diisocyanate(MDI)as a cross-linking agent to prepare modified chitosan MDI-CS through cross-linking reaction,through a variety of characterization methods analysis,proved the success of the cross-linking modification method.Through the adsorption experiment,the maximum adsorption capacity of MDI-CS for methyl orange and methylene blue is 97.43mg/g and 93.14mg,respectively.In the fitting of adsorption kinetic model and adsorption isotherm model,MDI-CS and quasi-second-order kinetic equation and Langmuir adsorption isotherm model show better fit and correlation.(3)Fe₃O₄ was synthesized by solvothermal method and added to chitosan to participate in the modification,so that the composite material has magnetic properties and is convenient for recycling.Finally,Fe₃O₄/HDI-CS was synthesized and analyzed by various characterization methods.Proved the success of its cross-linking modification.Through adsorption experiments,the maximum adsorption capacity of Fe₃O₄/HDI-CS for methyl orange and methylene blue is 149.35 mg/g and 106.43 mg,respectively.In the fitting of adsorption kinetic model and adsorption isotherm model,Fe₃O₄/HDI-CS and quasi-second-order kinetic equation and Langmuir adsorption isotherm model showed better fit and correlation.