The removal of impurities from water or wastewater by the membrane filtration process has become more reliable due to good hydraulic performance and high permeate quality. The filterability of the membrane can be improved by having a material with a specific pore structure and good hydrophilic properties. This work aims at preparing a polyvinylidene fluoride (PVDF) membrane incorporated with phospholipid in the form of a 2-methacryloyloxyethyl phosphorylcholine, polymeric additive in the form of polyvinylpyrrolidone, and its combination with inorganic nanosilica from a renewable source derived from bagasse. The resulting membrane morphologies were analyzed by using scanning electron microscopy. Furthermore, atomic force microscopy was performed to analyze the membrane surface roughness. The chemical compositions of the resulting membranes were identified using Fourier transform infrared. A lab-scale cross-flow filtration system module was used to evaluate the membrane’s hydraulic and separation performance by the filtration of humic acid (HA) solution as the model contaminant. Results showed that the additives improved the membrane surface hydrophilicity. All modified membranes also showed up to five times higher water permeability than the pristine PVDF, thanks to the improved structure. Additionally, all membrane samples showed HA rejections of 75–90%.
Biofouling on the membrane surface leads to performance deficiencies in membrane filtration. In this study, the application of ginger extract as a bio-based additive to enhance membrane antibiofouling properties was investigated. The extract was dispersed in a dimethyl acetamide (DMAc) solvent together with polyvinylidene fluoride (PVDF) to enhance biofouling resistance of the resulting membrane due to its antibiotic property. The concentrations of the ginger extract in the dope solution were varied in the range of 0–0.1 wt %. The antibacterial property of the resulting membranes was assessed using the Kirby Bauer disc diffusion method. The results show an inhibition zone formed around the PVDF/ginger membrane against Escherichia coli and Staphylococcus aureus demonstrating the efficacy of the residual ginger extract in the membrane matrix to impose the antibiofouling property. The addition of the ginger extract also enhanced the hydrophilicity in the membrane surface by lowering the contact angle from 93° to 85°, which was in good agreement with the increase in the pure water flux of up to 62%.
23 March 2023 in Macromolecular Chemistry and Physics
Membrane-based processes are a promising technology in water and wastewater treatments, to supply clean and secure water. However, during membrane filtration, biofouling phenomena severely hamper the performance, leading to permanent detrimental impacts. Moreover, regular chemical cleaning is ineffective in the long-run for overcoming biofouling, because it weakens the membrane structure. Therefore, the development of a membrane material with superior anti-biofouling performance is seen as an attractive option. Hydrophilic-anti-bacterial precursor polyethylene glycol-silver nanoparticles (PEG-AgNPs) were synthesized in this study, using a sol-gel method, to mitigate biofouling on the polyethersulfone (PES) membrane surface. The functionalization of the PEG-AgNP hybrid material on a PES membrane was achieved through a simple blending technique. The PES/PEG-AgNP membrane was manufactured via the non-solvent induced phase separation method. The anti-biofouling performance was experimentally measured as the flux recovery ratio (FRR) of the prepared membrane, before and after incubation in E. coli culture for 48 h. Nanomaterial characterization confirmed that the PEG-AgNPs had hydrophilic-anti-bacterial properties. The substantial improvements in membrane performance after adding PEG-AgNPs were evaluated in terms of the water flux and FRR after the membranes experienced biofouling. The results showed that the PEG-AgNPs significantly increased the water flux of the PES membrane, from 2.87 L·m−2·h−1 to 172.84 L·m−2·h−1. The anti-biofouling performance of the PES pristine membrane used as a benchmark showed only 1% FRR, due to severe biofouling. In contrast, the incorporation of PEG-AgNPs in the PES membrane decreased live bacteria by 98%. It enhanced the FRR of anti-biofouling up to 79%, higher than the PES/PEG and PES/Ag membranes.
Membrane properties are highly affected by the composition of the polymer solutions that make up the membrane material and their influence in the filtration performance on the separation or purification process. This paper studies the effects of the addition of pluronic (Plu) and patchouli oil (PO) in a polyethersulfone (PES) solution on the membrane morphology, membrane hydrophilicity, and filtration performance in the pesticide removal compound in the water sample. Three types of membranes with the composition of PES, PES + Plu, and PES + Plu + patchouli oil were prepared through a polymer phase inversion technique in an aqueous solvent. The resulting membranes were then analyzed and tested for their mechanical properties, hydrophilicity, antimicrobial properties, and filtration performance (cross-flow ultrafiltration). The results show that all of the prepared membranes could reject 75% of the pesticide. The modification of the PES membrane with Plu was shown to increase the overall pore size by altering the pore morphology of the pristine PES, which eventually increased the permeation flux of the ultrafiltration process. Furthermore, patchouli oil added antimicrobial properties, potentially minimizing the biofilm formation on the membrane surface.