Fabrication And Properties Of Functionalized Cellulose Acetate Electrospun Nanofiber Membranes For Adsorption

Electrospun nanofiber membrane has the advantages of adjustable pore size,high porosity,and large specific surface area.Most important,the nanofibrous membrane can get rid of organic pollutants such as antibiotics and dyes in wastewater by adsorption,and meanwhile,remove micro-plastic particles in water by filtration.Thus,electrospun nanofibrous membrane could be regarded as a good candidate for practical wastewater treatment.To prepare the electrospun nanofiber membrane with a high filtration and adsorption capability,a two-nozzle electrospinning equipment and cellulose triacetate(CTA)as the raw material were employed for the fabrication of CTA nanofiber membranes with uniform fiber diameter,beads free,adjustable pore size and high porosity.In details,CTA-COOH nanofiber membrane was prepared by alkaline hydrolysis and 2,2,6,6-tetramethylpiperidine-1-oxide(TEMPO)oxidation.We innovatively integrated hydrolysis and TEMPO oxidation reaction into one-step modification.Through the modification,the acetyl group on CTA was removed and the carboxyl group was introduced to improve its filtration and adsorption performance,as a result,CTA-COOH nanofiber membranes with excellent filtration and adsorption capability,recyclable,and cost-effectiveness were fabricated successfully.Meanwhile,the structure and properties of the nanofiber membrane were characterized by scanning electron microscopy,infrared spectroscopy and tensile experiments.The results show that through the one-step modification,the CTA-COOH nanofiber membrane also exhibited excellent mechanical properties and therefore,could be used as a self-supporting membrane,which was benefit for recycling and reuse of the nanofibrous membranes.Furthermore,Bismarck Brown Y(BBY)was used to understand the adsorption behavior of CTA-COOH nanofiber membrane against dyes.The adsorption shows that CTA-COOH nanofiber membrane has excellent adsorption and regeneration properties for BBY.The maximum adsorption capacity for BBY was 158.73 mg/g,which is higher than that of most adsorption materials.The regeneration rate can still reach 97% after 17 cycles of regeneration.For the practical application,CTA-COOH nanofiber membrane-based membrane module was prepared and used to treat wastewater containing BBY.The results showed that CTA-COOH nanofiber membrane had excellent practical application potential in treating BBY wastewater.At a flow rate of 2.0m L/min,the membrane module can purify 5.960 L of BBY wastewater,and meanwhile,the retention rate remained at 100%.Furthermore,the adsorption mechanism is discussed,and the adsorption process may mainly depends on hydrogen bonding between the adsorbent and target containments.Moreover,flumequine(FLU)as the representative of antibiotics and polystyrene microspheres were selected as the representative of microplastics to study the adsorption and filtration performance of CTA-COOH nanofiber membrane on microplastics removal and the adsorption of antibiotics,respectively.It was showed that CTA-COOH nanofiber membrane has high adsorption capacity and regeneration ability for FLU.The maximum adsorption capacity for FLU can reach 8.47 mg/g.The regeneration rate can still reach 80% after 15 cycles of regeneration.Furthermore,the adsorption mechanism may mainly depended on hydrophobic interaction between the nanofibrous membrane and the antibiotics.Meanwhile,the filtration experiment shows that CTA-COOH nanofiber membrane has high filtration efficiency and selectivity,evidenced by the retention rates of 0.6 μm and0.8 μm nanoparticles were 0% and 100%,respectively.