A hydrophilicity gradient control mechanism for fabricating delamination-free dual-layer membranes

Xia, Qian-Cheng; Wang, Jue; Wang, Xiao; Chen, Bo-Zhi; Guo, Jialin; Jia, Tian-Zhi; Sun, Shi‐Peng

doi:10.1016/j.memsci.2017.06.021

Cited by 68 publications

(25 citation statements)

References 40 publications

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“…Dual-layered membranes have also been prepared in the past using traditional membrane manufacturing methods 43,44 . They usually use different polymer solutions to cast the two layers to tailor the membrane properties in a certain way.…”

Section: Please Do Not Adjust Marginsmentioning

confidence: 99%

High-performance PVDF membranes prepared by the combined crystallisation and diffusion (CCD) method using a dual-casting technique: a breakthrough for water treatment applications

Shah

Wang

2021

Energy Environ. Sci.

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Section: Please Do Not Adjust Marginsmentioning

confidence: 99%

High-performance PVDF membranes prepared by the combined crystallisation and diffusion (CCD) method using a dual-casting technique: a breakthrough for water treatment applications

Shah

Wang

2021

Energy Environ. Sci.

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“…Nevertheless, the delamination during the phase inversion process, which is due to the difference in the properties of the two materials, has been widely accepted as the major hurdle for the practical application of dual‐layer membranes. Our group first discovered that the delamination issue could be solved by designing the two layers with descending hydrophobicity 30 . When the bottom layer is more hydrophilic than the top layer, water is prone to quickly penetrate from the top layer to the bottom layer, instead of accumulating at the membrane interface during the phase inversion process.…”

Section: Introductionmentioning

confidence: 99%

“…Our group first discovered that the delamination issue could be solved by designing the two layers with descending hydrophobicity. 30 When the bottom layer is more hydrophilic than the top layer, water is prone to quickly penetrate from the top layer to the bottom layer, instead of accumulating at the membrane interface during the phase inversion process. We further established the relationship between solubility parameter difference (SPD) and delamination-adhesion transition.…”

Section: Introductionmentioning

confidence: 99%

Dual‐layer membrane with hierarchical hydrophobicity and transport channels for nonpolar organic solvent nanofiltration

Wang

Liu

et al. 2021

AIChE Journal

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Nonpolar solvent separation is widely used in petroleum, chemical, food industries, but traditional separation methods consume intensive energy. State-of-art organic solvent nanofiltration membranes require complex modifications for nonpolar solvent transport. For the first time, we propose the concurrent modification of the surface, interface and support layer of dual-layer membranes with three additives (perfluorodecylamine, fluoro substituted aromatic amine, silica nanoparticles) in a onestep cocasting process. A delamination-free dual-layer membrane was obtained with a hierarchical hydrophobicity and transport channels. The novel designed structure elevated the pure n-hexane permeance (28.75 L m −2 hr −1 bar −1) by 3 orders of magnitude with a high lecithin rejection (98.7%). This method of synergistically controlling the hierarchical structures and properties of dual-layer membranes can significantly shorten the preparation process of high-performance nonpolar solvent nanofiltration membranes.

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“…It was report that two of the main factors causing layer delamination include variation in phase inversion rates during phase inversion process and uneven shrinkage rates of different layering materials during membrane formation [23]. Hence, various methods have been adopted to resolve this issue, such as choice of compatible/miscible polymer types for the two layers [24], co-extrusion (of hollow fibers) or co-coating techniques [25], choice of additive (non-solvent) or diluent [26]. However, the above-mentioned work was mainly focused on hydrophilic/hydrophilic dual-layer membranes.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of novel Janus membrane by nonsolvent thermally induced phase separation (NTIPS) for enhanced performance in membrane distillation

Liu

Xiao

Bao

et al. 2018

Journal of Membrane Science

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This study proposed to use the nonsolvent thermally induced phase separation (NTIPS) method to fabricate a novel Janus membrane for MD applications. The as-prepared dual-layer membrane consisted of a thin hydrophobic PVDF top-layer and a relatively thick hydrophilic PVDF-PVA sub-layer. By adopting a facile one-step co-casting technique and water soluble diluent ε-caprolactam (CPL), delamination-free dual-layer membrane was obtained. The SEM morphologies and FTIR crystalline analyses suggested the membrane formation mechanisms, where the hydrophobic top-layer was formed via NTIPS process, resulting in an ultra-thin dense skin with finger-like pores formed beneath; while the hydrophilic sub-layer was induced by TIPS, producing highly porous cellular structure with high degree pore interconnectivity. Combining the structural observation and MD performance results, suitable fabrication parameters were identified as a PVDF concentration of 15 wt% for the hydrophobic layer and coagulation temperature between 20-40 o C. The total membrane thickness was optimized as 100-150 μm, given the thickness of hydrophobic layer kept within an optimal range of 30-60 μm to ensure minimal mass transfer resistance. The Janus membrane exhibited stable salt rejection above 99.5% over continuous MD runs and superior permeation flux up to 165.3 kg•m-2 •h-1 at 80 o C, which was remarkably higher than reported MD membranes.

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A hydrophilicity gradient control mechanism for fabricating delamination-free dual-layer membranes

Cited by 68 publications

References 40 publications

High-performance PVDF membranes prepared by the combined crystallisation and diffusion (CCD) method using a dual-casting technique: a breakthrough for water treatment applications

High-performance PVDF membranes prepared by the combined crystallisation and diffusion (CCD) method using a dual-casting technique: a breakthrough for water treatment applications

Dual‐layer membrane with hierarchical hydrophobicity and transport channels for nonpolar organic solvent nanofiltration

Fabrication of novel Janus membrane by nonsolvent thermally induced phase separation (NTIPS) for enhanced performance in membrane distillation

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