| In recent years,water safety has always been an important part of environmental pollution,and the treatment of water pollution has always been concerned.It is one of the most widely used methods to treat polluted water by adsorption,and the selection of adsorbent materials has become a key problem.Since the emergence of nano adsorption materials,scholars have paid extensive attention to the research.As a typical representative of nano materials,metal-organic-frameworks(MOFs)have been applied in many fields.It has been proved that MOFs can be used in gas adsorption,molecular separation,catalysis,drug delivery and other fields.Chitosan,as a natural polymer material,is biocompatible and nontoxic,with large reserves and low production cost.And the hydroxyl and amino groups in the molecular structure make it have high biological activity,and can be modified by a variety of substances to get more chitosan derivatives,which has great research and application significance.In this project,a new safety material was synthesized to deal with the problem of organic pollution in water safety by using the MOFs and chitosan.The main contents are as follows.In this paper,ZIF-8 nanoparticles,one kind of MOFS,were synthesized from Zn(NO3)2ยท6H2O and 2-methylimi-dazole by stirring.The first group of leaf-ZIF-8nanoparticles was synthesized by stirring the solution with the molar ratio of metal ions to organic ligan-ds of 1:4,and the second group of hexahedral ZIF-8 nanoparticles was synthesized by stirring the solution with the molar ratio of metal ions to organic ligands of 1:8.The two groups of ZIF-8 nanoparticles were characterized by SEM,XRD and FTIR.The effects of molar ratio of metal ions to organic ligands and reaction time on the morphology and structure of metal organic frameworks were investigated,as well as the adsorption performance of ZIF-8 particles for organic pollutants.In order to explore the influence of fluid velocity on droplet diameter in microfluidic droplet technology,the shear forming process of microfluidic droplet was simulated by COMSOL Multiphysics software.The T-shaped microchannel needed for droplet shear was established.The basic parameters of two phases fluid were set and the fluid velocity was changed.The influence of two phases fluid velocity on effective droplet diameter was obtained.ZIF-8/Chitosan oligosaccharide composite nanoparticles with multi-stage pore structure were prepared by microfluidic droplet technology.The chitosan oligosaccharide aqueous solution was used as the dispersion phase,and the ZIF-8nanoparticles prepared in Chapter 3 were added into the dispersion phase.Using the mixed solution of benzyl benzoate and soybean oil as the continuous phase and adding glutaraldehyde as cross-linking agent,the W/O single emulsion droplet produced in microfluidic T tube device was used as template to prepare ZIF-8/ chitosan oligosaccharide composite micro droplet.Finally,the composite particles were obtained by cross-linking reaction.The structure and morphology of ZIF-8/ Chitosan oligosaccharide composite microparticles with different pore structures were characterized by optical microscope and scanning electron microscope.The results showed that the composite microparticles prepared by microfluidic control had good monodispersity,regular morphology and uniform size.At the same time,ZIF-8 /Chitosan oligosaccharide composite nanoparticles with different structure and multistage pore structure can be obtained by adding ZIF-8 nanoparticles with different content.The adsorption properties of ZIF8 / Chitosan oligosaccharide microparticles with different pore structures for organic pollutants were investigated by using methyl orange dye as organic pollutant model.The results show that ZIF-8 / Chitosan oligosaccharide composite microparticles have strong adsorption capacity for methyl orange dye,and the change of pore structure will also affect the adsorption performance of the composite microparticles.It is one kind of adsorbent material with great research value. |
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