Synthesis of patterned PVDF ultrafiltration membranes: Spray-modified non-solvent induced phase separation

Abstract

Patterned membranes have been attractive for the mitigation of fouling in membrane processes, but existing patterning methods are rather in-effective in terms of scalability and performance due to pore-size reduction and patterning at the non-selective membrane side. Polyvinylidene fluoride (PVDF) was used now to synthesize patterned membranes via the spray-modified non-solvent induced phase separation (s-NIPS), a recently developed technique that avoids the current drawbacks of patterned membranes. However, PVDF intrinsically suffers from a slow phase separation, while very fast fixation of the patterns is crucial with this synthesis method. Therefore, the casting solution was optimized towards an accelerated process of phase inversion by systematically studying the effect of polymer concentration, addition of poly(vinylpyrrolidone) (PVP), addition of non-solvent (H2O) and use of different casting solvents for adequate patterning of the membranes. SEM analysis and pure water permeance of the synthesized membranes assessed the homogeneity and pattern formation for each membrane. The most optimal casting solution composition comprised of 20 wt% PVDF, 6.7 wt% PVP and 1 wt% H2O which resulted in homogenously patterned PVDF membranes. The optimized patterned membrane showed a 9 fold increase in PWP as compared to the reference flat membrane thanks to the addition of PVP and H2O as well as the additional surface area. In the filtration of proteins, the water permeance of the membranes improved drastically (+140%) upon patterning with only a moderate loss of BSA rejection (from 90% to 71%) as compared to the corresponding flat membrane. Realisation of patterning via the s-NIPS method resulted in a higher effective membrane surface area combined with an increased membrane porosity. Reduced flux decline of the patterned membrane (52%) as compared to the flat membrane (62%) during continuous BSA filtration also proved the antifouling potential of the created patterns.

Harvesting microalgal biomass using negatively charged polysulfone patterned membranes: Influence of pattern shapes and mechanism of fouling mitigation

“…In addition to the hydrophilicity and surface charge modifications, surface patterning is considered an emerging method to alleviate fouling due to the unique hydrodynamic flow behavior near the membrane surface and the extended active area (Ilyas et al, 2020;Jung and Ahn, 2019;Marbelia et al, 2020;Zhao et al, 2020b).…”

“…The polymer solution is cast using a modified patterned knife, and non-solvent is simultaneously sprayed on the cast film to rapidly solidify the surface pattern. The membrane prepared using this modified phase inversion method showed a significantly higher clean water permeance (CWP) than when using the traditional phase inversion method (Ilyas et al, 2020;Marbelia et al, 2020;Zhao et al, 2020b). The anti-fouling property of the patterned membrane is highly related to the pattern shape (Choi et al, 2017).…”

Tamisolve® NxG as an Alternative Non-Toxic Solvent for the Preparation of Porous Poly (Vinylidene Fluoride) Membranes

“…Crystallization experiments were investigated with the same PVDF-HFP membranes using Tamisolve ® NxG as a solvent via non-solvent phase separation (NIPS) by Saidi et al [ 59 ]. Tamisolve ® NxG was also selected for producing a support nanofiltration (NF) membrane for crosslinked PVDF [ 60 ] and for NF membranes preparation via spray-modified non-solvent induced phase separation (s-NIPS) [ 61 ]. Another important study with Tamisolve ® NxG was conducted by Bagnato et al [ 62 ].…”

Modification of the Surface Morphology and Properties of Graphene Oxide and Multi-Walled Carbon Nanotube-Based Polyvinylidene Fluoride Membranes According to Changes in Non-Solvent Temperature

“…The most common membrane manufacturing method is the phase inversion method, which includes non-solvent-induced phase separation (NIPS) [ 25 , 26 , 27 , 28 ], thermally-induced phase inversion (TIPS) [ 25 , 29 ], and vapor-induced phase separation (VIPS) [ 30 , 31 ]. The NIPS method has been most widely used to prepare homogeneous solution [ 28 ].…”