Preparation Of Multi-scale Chitosan Nanofiber Membrane And Its Adsorption And Filtration Performance

Electrospinning technology is one of the effective means to obtain nanofibers,and its equipment is simple and convenient to operate.And the nanofiber membrane prepared by electrospinning technology has a large specific surface area and porosity.Therefore,electrospinning technology has great application prospects in the field of filtration and adsorption.This paper studies the preparation process of chitosan(CS)nanofiber membrane.A multi-scale CS nanofiber membrane was prepared,and its filtration and adsorption properties were studied.The research work of this paper mainly includes the following three parts:1.Electrospinning technology was used to prepare multi-scale CS nanofiber membranes,the morphology and performance of the membranes were analyzed by scanning electron microscopy,infrared spectroscopy,differential scanning calorimetry and other analytical methods.Experiments have found that when the process parameters are:temperature 25?,relative humidity 50%,CS concentration 6%,storage time for one day,sodium lauryl sulfate addition 0.2%,voltage 18k V,and receiving distance 10cm,the obtained fiber membrane has the highest nanonets coverage and the most uniform distribution.The filtration performance of the membrane was tested.2.Different concentrations of Na₂CO₃ solutions were used to cross-link the multi-scale CS nanofiber membranes prepared under the optimal process conditions,and the best treatment conditions were studied.The study found that when the concentration of Na₂CO₃ solution was 20%and the cross-linking time was 30min,the obtained fiber membrane could maintain the fiber morphology and had the best stability in acid.The adsorption performance of Na₂CO₃ cross-linked multi-scale CS nanofiber membranes for heavy metals was studied,and the effects of adsorption conditions such as p H,adsorption time,and temperature on adsorption were analyzed.Experiments have found that under the optimal adsorption conditions,the adsorption capacity of the membrane on Cu²⁺can reach 204.92mg/g,which is far greater than the43.86mg/g of Pb²⁺.The adsorption behavior of the membrane on Cu²⁺and Pb²⁺was continued to be analyzed,it is found that the adsorption of Cu²⁺and Pb²⁺belongs to Langmuir monolayer adsorption,which conforms to the intra-particle diffusion model.The adsorption process includes both physical adsorption and chemical adsorption.And the membrane has good recycling performance.3.The adsorption performance of the Na₂CO₃ cross-linked multi-scale CS nanofiber membrane for dyes was studied,and the effects of adsorption conditions such as p H,adsorption time,and temperature on the adsorption were analyzed.Experiments have found that under the optimal adsorption conditions,the adsorption capacity of the membrane for the anionic dye reactive red can reach 709.22mg/g,and the cationic dye methylene blue is hardly adsorbed.The adsorption behavior of the membrane on the reactive red dye was continued to be analyzed,it is found that the adsorption of the reactive red belongs to the Langmuir monolayer adsorption,which conforms to the pseudo-second-order kinetic equation,and the adsorption process is chemical adsorption.And the membrane has good recycling performance.