Authors: Mustafa N. Taher | Sama A. Al-Mutwalli | Frank Lipnizki | Derya Y. Köseoğlu-İmer
Source: Lund University Publications (Lund University) (article, 2023-11-13)
Field: Materials Science — Biomaterials

Fabrication and Application of polymeric and composite nanofiber membranes for wastewater reclamation: The effect of fabrication time Electrospun nanofiber membranes (ENMs) with unique porous 3D network structure exhibit properties such as high porosity and surface area, fine-tuned surface functionality and uniform pore sizes. This makes them candidates for water/wastewater applications with excellent flow. This study focuses on the fabrication of polymeric and composite ENMs from polyacrylonitrile (PAN) and nanoclay (NC) and their application for wastewater treatment. The effect of different manufacturing times was investigated, assuming that increasing the manufacturing time could lead to the formation of a thin film layer on the top of the ENMs. The formation of a thin film layer could improve the rejection performance of ENMs without the need for further treatment such as interfacial polymerisation to form a thin film layer. An NS1/Plus E spinner/sprayer was used to produce the ENMs. Two spinning solutions of 12% w/w PAN and 12% w/w PAN + 5% w/w NC were prepared separately in dimethylformamide (DMF) and used to prepare PAN-ENM and COM-ENM, respectively. All ENMs were prepared on non-woven polyester fabrics. The fabrication parameters were a voltage of 15 kV, a flow rate of the spinning solution of 0.5 mL/h, a distance of 18 cm between nozzle and drum, and a fabrication time of 2, 4, 6 and 8 hours. The fabricated ENMs were characterised using SEM-EDS, FTIR and BET N2 adsorption/desorption techniques. The SEM images showed that the addition of NC increased the diameter of the fibres from 164 to 355 nm. Furthermore, the SEM images showed that even after 8 hours of electrospinning, a thin film layer could not form on the top of the ENMs. This refutes the assumption made earlier in this study regarding the manufacturing time. Increasing the manufacturing time had no significant effect on the fibre diameter. Analysis of BET showed that adding NC and increasing the fabrication time resulted in a 3 times larger surface area of COM-ENM compared to PAN-ENM. The results from FTIR and SEM-EDS were correlated and confirmed the incorporation of NC into the PAN matrix.Furthermore, a filtration system operated in gravity driven membrane mode (GDM) at 50 mbar was used. The feed solution of the GDM system was the effluent from an Upflow Anaerobic Sludge Blanket (UASB) reactor treating municipal wastewater with the following characterization, pH: 7.4, total suspended solid (TSS): 40 mg/L, turbidity: 35 NTU, chemical oxygen demand (COD): 70 mg/L. At the beginning of filtration, the effect of fabrication time on the flux was clear with a lower flux for ENMs fabricated at longer time. However, at the end of the filtration process (24 hours), the stable fluxes of almost all ENMs were comparable in the range of 4.0 - 5.5 LMH. The permeate characterization revealed that fabrication time can significantly influence the quality of the permeate. Rejection increased as fabrication time increased with COM-ENM showing better permeate quality. The highest rejection of turbidity, TSS and COD were 84, 98 and 83% for COM-ENM fabricated at 8 hours. Permeate will be further analyzed for rejection of ions (such as NH4+, PO43-, etc.) and particle size distribution. Fabrication ; Polyacrylonitrile ; Spinning ; Electrospinning ; Membrane ; Porosity ; Composite number ; Nanofiber Electrospun Nanofibers in Biomedical Applications ; Membrane Separation Technologies ; Advanced Cellulose Research Studies