Effect of ethanol in the coagulation bath on the structure and performance of PVDF‐g‐PEGMA/PVDF membrane

Abstract

This report investigated the effect of ethanol content in the coagulation bath on the surface composition, membrane pore size structure, pure water flux, and permeability of the amphiphilic polymer polyvinylidene fluoride (PVDF)-g-poly (ethylene glycol) methyl ether methacrylate (PEGMA)-modified PVDF membrane. The study found that pore size and their distribution and, as a result, membrane permeability, can also be easily controlled by adjusting ethanol content in the coagulation bath. Membrane water fluxes formed by the coagulation baths with 0, 10, 20, and 30% of ethanol were 1843. 65, 2774.61, 4391.88, and 5142.35 L (m −2 Áh −1 ). When the content of ethanol in the coagulation bath is high, the surface enrichment of PEGMA slightly decreases, and the surface becomes rougher. Thus, the decrease of the hydrophilic functional groups on the surface of the membrane and the increase of the roughness leads to the deterioration of the hydrophilicity of the membranes surface.

Creating membrane‐air‐liquid interface through a rough hierarchy structure for membrane gas absorption to remove CO 2

“…Ethanol as a weak coagulation medium reduces the solvent/non-solvent exchange rate, resulting in a slow membrane precipitation process. 43,44 Therefore, the formed micro-valley structures are shallower (Figure 5C, SEM image on the left). Although the horizontal and vertical line valleys can still be observed from the SEM image, it is not deep compared with the DI-coagulated membrane.…”

“…It is commonly known that water is a strong coagulation medium that can induce high solvent/nonsolvent exchange rate and subsequently promote the rapid membrane precipitation process. 43 Because of the fast membrane precipitation rate, the pattern formed on the surface of the membrane is deeper. In Figure 5B (the SEM image on the left), 3D and sharp horizontal and vertical line valleys can be observed.…”

Preparation and characterization of superior hydrophilic PVDF/DA membranes by the self-polymerization approach of dopamine

“…Membrane materials with high water flux, high strength, and antifouling properties are key to enhancing MBR treatment, and PVDF has become the main membrane material for microfiltration and ultrafiltration in wastewater treatment because of its easy operational performance, good thermal stability, and excellent chemical stability ( Ayyaru and Ahn, 2017 ; Wang J. et al, 2019 ; Xiao et al, 2019 ). Due to the strong hydrophobicity of PVDF, it leads to low water flux after membrane formation, serious membrane contamination problems, and reduced membrane lifetime, which greatly limit the application of membrane bioreactors ( Meng et al, 2017 ; Su and Zhang, 2018 ; Tang et al, 2019 ). Therefore, it is important to modify the membranes with necessary hydrophilic modifications to improve the overall performance ( Sun et al, 2013 ; Zhao et al, 2015 ; Al Mayyahi, 2018 ).…”

Fabrication of PVDF mixed matrix nanofiltration membranes incorporated with TiO2 nanoparticles and an amphiphilic PVDF‐g‐PMMA copolymer

“…11,15 Polyvinylidene fluoride (PVDF) is a microfiltration, ultrafiltration, nanofiltration and pervaporation membrane material which is commercially proposed because of possessing several good features including its good membrane forming ability, outstanding antifouling and excellent dye rejection performance. 19,20 Due to the fact that PVDF polymer is naturally hydrophobic and, therefore, it is prone to membrane fouling, 21,22 a variety of promising alternatives, for example, application of amphiphilic copolymers via atom transfer radical polymerization (ATRP), introducing inorganic nanoparticles (NPs), and so on, have been studied in order to improve hydrophilicity and antifouling properties of PVDF membranes. [23][24][25] So far, many researches have reported numerous chemical and physical modification techniques to enhance the hydrophilicity of PVDF membranes.…”