Preparation Of AOPAN/RC/PU Nanofibers And Their Dynamic Adsorption Properties Of Metal Ions

With the development of technology and the continuous improvement of living standards,water resources to become serious.The destruction of the natural environment is caused by human beings in social activities.In this article,the blend nanofibers were prepared by electrospinning technology.The functional nanofibers were prepared by a series of chemical modifications,and the large number of groups,such as hydroxyl groups,amidoxime groups and so on,were formed on their surface.In research,it showed the high efficiency in the field of water treatment by using the unique advantages of nanofibers and combining with adsorption and membrane separation technology.PAN/CA/PU blend nanofibers were prepared by electrospinning from the materials of polyurethane(PU),polyacrylonitrile(PAN)and cellulose acetate(CA)polymer.CA and PAN were respectively converted into regenerated cellulose(RC)and amidoxime-based polyacrylonitrile(AOPAN)after hydrolysis and amidoxime treatment.AOPAN/RC/PU functional blend nanofibers were prepared.In the experiment,the blend nanofibers were prepared by the electrospinning,the spinning voltage and spinning flow rate of the electrospinning were explored,and the optimal parameters of the electrospinning were analyzed.Different blend nanofibers were characterized by scanning electron microscopy(SEM)and infrared spectroscopy(FTIR).The hydrophilic properties and mechanical properties were tested.The results show that when the ratio of PAN/CA/PU in the spinning solution is 1:6:3 and the total mass fraction is 10%,the optimum process parameters of PAN/CA/PU blend nanofibers prepared by electrospinning are:the spinning voltage is 18 kV,and the spinning flow rate is 0.50 mL/h.The blend nanofibers prepared by electrospinning have complete morphology,uniform distribution,the fibrous membrane has a high porosity,and poor hydrophilicity of the fibers.The surface of the fiber has a large number of functional groups such as amidoxime and hydroxyl groups after chemical treatment.The hydrophilicity is improved and the fiber has good mechanical properties.The AOPAN/RC/PU blend nanofibrous membrane were used as the separation layer and a dynamic separation system was constructed.The dynamic adsorption performance of Fe(?)was studied.In the experiment,the blend nanofibers were characterized by SEM and EDS.The relationships between the number of blend nanofiber membrane layers and dynamic adsorption rate,solution flow rate were studied.The relationships between Fe(?)concentration and dynamic adsorption rate,solution flow rate were explored.Reusable performance was also explored.The results show that the rate of the dynamic adsorption is up to 100%under 8 cm of the condition of liquid column height,5 layers of the membrane layer and 5 mg/L of the concentration Fe(?).When the concentration of Fe(?)is 300 mg/L,the data of the dynamic adsorption is consistent with the Thomas and Yoon-Nelson dynamic adsorption model,and the amounts of the equilibrium adsorption are 116.95 mg/g and 113.27 mg/g.When the concentration of Fe(?)is 5 mg/L,the desorption rate of Fe(?)on blend nanofibrous membranes is higher than 85%,and the dynamic adsorption rate is higher than 99%after three consecutive adsorption-desorption cycles.The excellent reusability of the blend nanofibrous membranes is had,and the high dynamic adsorption performance of them is had for trace Fe(?)solution.A water filtration system was designed,and AOPAN/RC/PU blend nanofibers were used as a filter layer.A water filtration device was constructed.The dynamic adsorption properties of Pb(?),Cd(?),Cr(?),Cu(?)and Al(?)was determined under the concentration is 5 mg/L.Its reusability was explored.The results show that the dynamic adsorption capacity of the materials for trace amounts of Al(?),Pb(?),Cu(?),Cr(?)and Cd(?)after dynamic adsorption experiments is:Al(?)=Pb(?)>Cu(?)>Cr(?)>Cd(?).The desorption rate of the blend nanofiber membranes were higher than 85%,and the dynamic adsorption of Al(?)and Pb(?)was better than that of the other three metal ions,indicating that the material has excellent reusability for trace mixed heavy metal ions.In addition,a three-stage filtration system was constructed in the study.The membrane flux of the inner layer of the third-stage filtration system was 39.23 L/(m2·min),indicating that the composite nanofiber membrane has a large membrane flux.