Blending modification to porous polyvinylidene fluoride (PVDF) membranes prepared via combined crystallisation and diffusion (CCD) technique

Shah, Vatsal; Wang, Bo; Li, K.

doi:10.1016/j.memsci.2020.118708

Cited by 30 publications

(8 citation statements)

References 40 publications

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“…As it can be seen from the Figure 7, three absorption peaks of PVDF at 1,401 cm −1 , 1,175 cm −1 and 873 cm −1 are corresponded to the deformation vibrations of CH 2 , asymmetric stretching of F-C-F and skeletal vibration of C-C, respectively (Shah et al, 2021;Kachhadiya and Murthy, 2022). With the addition of inorganic salt additives of LiCl, the emerging peaks on the M0 membrane at 1,432 cm −1 , 1275cm −1 and 1,070 cm −1 were ascribed to the β-phase polymorph (Shah et al, 2021). For M3 membrane, the new peaks at 1,507 cm −1 and 587 cm −1 are corresponding to the characteristic peaks of MIL-53(Al).…”

Section: Chemical Properties Of the Membranesmentioning

confidence: 93%

PVDF/MOFs mixed matrix ultrafiltration membrane for efficient water treatment

Cheng

Li²,

Xiao³

et al. 2022

Front. Chem.

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Polyvinylidene fluoride (PVDF), with excellent mechanical strength, thermal stability and chemical corrosion resistance, has become an excellent material for separation membranes fabrication. However, the high hydrophobicity of PVDF membrane surface normally leads a decreased water permeability and serious membrane pollution, which ultimately result in low operational efficiency, short lifespan of membrane, high operation cost and other problems. Metal-organic frameworks (MOFs), have been widely applied for membrane modification due to its large specific surface area, large porosity and adjustable pore size. Currently, numerous MOFs have been synthesized and used to adjust the membrane separation properties. In this study, MIL-53(Al) were blended with PVDF casting solution to prepare ultrafiltration (UF) membrane through a phase separation technique. The optimal separation performance was achieved by varying the concentration of MIL-53(Al). The surface properties and microstructures of the as-prepared membranes with different MIL-53(Al) loading revealed that the incorporation of MIL-53(Al) enhanced the membrane hydrophilicity and increased the porosity and average pore size of the membrane. The optimal membrane decorated with 5 wt% MIL-53(Al) possessed a pure water permeability up to 43.60 L m−2 h−1 bar−1, while maintaining higher rejections towards BSA (82.09%). Meanwhile, the prepared MIL-53(Al)/LiCl@PVDF membranes exhibited an excellent antifouling performance.

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Section: Chemical Properties Of the Membranesmentioning

confidence: 93%

PVDF/MOFs mixed matrix ultrafiltration membrane for efficient water treatment

Cheng

Li²,

Xiao³

et al. 2022

Front. Chem.

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“…This membrane module with a dimension of a 14 cm length and a 3 cm outer diameter was designed. As shown in Figure b, although the water flux of the membrane module drops significantly with a continuous test for 17 h at a pressure of 2 bar, its flux remains stable around 2000 L m –2 h –1 , which is much higher than commercial membranes (in the range of 20–135 L m –2 h –1 bar –1 ) . The loose structure of the BCP/CNT layer, high porosity of the composite membrane, and the compaction of the PES support are the main reasons for the sharp flux decrease of the membrane module.…”

Section: Resultsmentioning

confidence: 92%

“…As shown in Figure 4b, although the water flux of the membrane module drops significantly with a continuous test for 17 h at a pressure of 2 bar, its flux remains stable around 2000 L m −2 h −1 , which is much higher than commercial membranes (in the range of 20−135 L m −2 h −1 bar −1 ). 44 The loose structure of the BCP/ CNT layer, high porosity of the composite membrane, and the compaction of the PES support are the main reasons for the sharp flux decrease of the membrane module. As shown in Figure 4c, the water flux of the PES support dramatically decreased from ∼40 000 to ∼15 000 L m −2 h −1 because of the compaction of the PES support itself.…”

Section: Resultsmentioning

confidence: 99%

Absolute and Fast Removal of Viruses and Bacteria from Water by Spraying-Assembled Carbon-Nanotube Membranes

Meng

et al. 2021

Environ. Sci. Technol.

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Membrane separation is able to efficiently remove pathogens like bacteria and viruses from water based on size exclusion. However, absolute and fast removal of pathogens requires highly permeable but selective membranes. Herein, we report the preparation of such advanced membranes using carbon nanotubes (CNTs) as one-dimensional building blocks. We first disperse CNTs with the help of an amphiphilic block copolymer, poly(2-dimethylaminoethyl methacrylate)-block-polystyrene (PDMAEMA-b-PS, abbreviated as BCP). The PS blocks adsorb on the surface of CNTs via the π–π interaction, while the PDMAEMA blocks are solvated, thus forming homogeneous and stable CNT dispersions. We then spray the CNT dispersions on porous substrates, producing composite membranes with assembled CNT layers as the selective layers. We demonstrate that the optimized membrane shows 100% rejection to phage viruses and bacteria (Escherichia coli) while giving a water permeance up to ∼3300 L m–2 h–1 bar–1. The performance of the resultant BCP/CNT membrane outperforms that of state-of-the-art membranes and commercial membranes. The BCP/CNT membrane can be used for multiple runs and regenerated by water rinsing. Membrane modules assembled from large-area membrane sheets sustain the capability of absolute and fast removal of viruses and bacteria.

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“…With regards to industry-standard PVDF UF membranes, most of them have pure water permeances around 50-200 litres per square meter membrane area per hour under 1 bar pressure difference across the membrane (see Table S2 in the ESI †). 20,38 To meet the operational needs of a filtration process, a larger membrane area is then required to compensate for this low permeance. This in turn limits the applicability of these PVDF filtration units in parts of the globe that are in dire need of effective and economical water treatment systems.…”

Section: Introductionmentioning

confidence: 99%

“…These crystals, after being leached out in an icy water bath, serve as pore templates in the final membrane. 20,38,39 To allow for the solvent crystal to grow, while the solvent molecules must diffuse towards the growing crystal, there must be counter diffusion of the polymer molecules away from the crystal and hence this process is called the combined crystallisation and diffusion method or CCD. This method employs DMSO as the solvent, as not only is it a greener and a more preferred alternative to other organic solvents 40 , but also has a relatively higher freezing point.…”

Section: Introductionmentioning

confidence: 99%