Synthesis, characterization and optimization of polyacrylonitrile electrospun nanofiber membranes

Abstract

The control of electrospinning process parameters, such as high electric potential, flow rate, screen distance and concentration becomes increasingly difficult. Electrospinning is capable of producing fibers in nanosize diameter range due to the increase of mechanical forces to drive the fiber formation process. Polyacrylonitrile (PAN) nanofiber membrane produced by electrospinnning was structurally developed to improve the performance of wastewater treatment. The dispersion of silica nanoparticle concentration in dope solution of 1 wt.% has changed the structural and mechanical properties of fibers. The fiber structure was examined in terms of pore size, contact angle, tensile strength, Young’s modulus, fourier transform infrared spectrometer (FTIR), and scanning electronic microscopy (SEM). The results indicated that the increase of polymer concentration and flow rate, the average fiber diameter increases. On the other hand, the increase of screen distance and electric potential decreased average fibers diameter. Young’s modulus and tensile strength increased by the addition of silica content at 1 wt.% and decreased with the increase of the silica content of 2 wt.%. The further addition of silica particles concentration produced more brittle and fragile PAN/silica composite fibers. The effect of silver functionalized membranes to pathogen removal was also studied and the tests were performed in a flow through system. Response Surface Methodology (RSM) was also performed to investigate the influence of the variables on the quality and quantity of permeate to attain the optimized conditions for preparing electrospun PAN fibers. Results from RSM were used to assess the interaction factors, namely, screen distance, polymer concentration and voltage. The quadratic models based on the responses resulted in potential of pore size, contact angle, young modulus and clean water permeation (CWP) to suitable chemical oxygen demand (COD), total suspended solids (TSS), ammonia nitrogen (NH3-N) and e. coli removal efficiencies. The results showed high removal of TSS, COD, NH3-N and e. coli at 96.18%, 91.82%, 68.89%, and no detectable, respectively. Therefore, it can be concluded that electrospun nanofibers membrane can be promising alternative materials in water filtration, especially as membrane for antibacterial and stand-alone microfiltration unit.