Preparation of high strength poly(vinylidene fluoride) porous membranes with cellular structure via vapor-induced phase separation

Zhao, Qian; Xie, Rui; Luo, Feng; Faraj, Yousef; Liu, Zhuang; Ju, Xin; Wang, Wei; Chu, Liang‐Yin

doi:10.1016/j.memsci.2017.10.068

Cited by 73 publications

(37 citation statements)

References 32 publications

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“…Extended exposure time leads to the coarsening process of the polymer-lean phase. The polymer-lean phase eventually produces pores, as these generate the cellular structure justified from the surface SEM image of M-5 in Figure 3 , as also reported by others [ 33 ]. Hence, the available time is limited for the growth of nuclei at shorter exposure times, which results in smaller macrovoids.…”

Section: Resultssupporting

confidence: 76%

Polyvinylidene Fluoride Membrane Via Vapour Induced Phase Separation for Oil/Water Emulsion Filtration

et al. 2021

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Membrane-based technology is an attractive option for the treatment of oily wastewater because of its high oil removal efficiency, small footprint and operational simplicity. However, filtration performance is highly restricted by membrane fouling, especially when treating oil/water emulsion as a result of strong interaction between oil droplets and the hydrophobic property of the membrane. This study explores the fabrication of polyvinylidene fluoride (PVDF)-based membrane via the vapour induced phase separation (VIPS) method while incorporating polyvinyl pyrrolidone (PVP) as a hydrophilic additive to encounter membrane fouling issues and improve membrane filterability. The resulting membranes were characterized and tested for oil/water emulsion filtration to evaluate their hydraulic, rejection and anti-fouling properties. Results show that the changes in membrane morphology and structure from typical macrovoids with finger-like substructure to cellular structure and larger membrane pore size were observed by the prolonged exposure time from 0 to 30 min through the VIPS method. The enhanced clean water permeability is attributed to the addition of PVP–LiCl in the dope solution that enlarges the mean flow pore size from 0.210 ± 0.1 to 7.709 ± 3.5 µm. The best performing membrane was the VIPS membrane with an exposure time of 5 min (M-5), showing oil/water emulsion permeability of 187 Lm−2 h−1 bar−1 and oil rejection of 91.3% as well as an elevation of 84% of clean water permeability compared to pristine PVDF developed using a typical non-solvent induced phase separation (NIPS) method. Despite the relatively high total fouling, M-5 was able to maintain its high permeability by water flushing as a simple operation for membrane fouling control. The performance was achieved thanks to combination of the large mean flow pore size and hydrophilic property from residual PVP in the membarne matrix. Overall, the results demonstrate the potential of the optimum VIPS method in the presence of PVP and LiCl additives for oil/water emulsion treatment.

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Section: Resultssupporting

confidence: 76%

Polyvinylidene Fluoride Membrane Via Vapour Induced Phase Separation for Oil/Water Emulsion Filtration

et al. 2021

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“…Samples were heated from 30 to 220 °C at a rate of 10 °C/min. 38 Raman spectra (DXR2xi Raman Imaging Microscope, Thermo Fisher) were acquired to identify the characteristic bands of different crystalline phases of PVDF in the fabricated membranes. The peak height ratio analysis of the membrane was performed using a 455 nm laser with a step length of 0.1 μm on the surface of 5 μm × 5 μm samples.…”

Section: Materials and Methodsmentioning

confidence: 99%

Superwettable PVDF/PVDF-g-PEGMA Ultrafiltration Membranes

Tiraferri

et al. 2020

ACS Omega

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Poly(vinylidene fluoride) (PVDF) is a common and inexpensive polymeric material used for membrane fabrication, but the inherent hydrophobicity of this polymer induces severe membranes fouling, which limits its applications and further developments. Herein, we prepared superwettable PVDF membranes by selecting suitable polymer concentration and blending with PVDF- graft -poly(ethylene glycol) methyl ether methacrylate (PVDF- g -PEGMA). This fascinating interfacial phenomenon causes the contact angle of water droplets to drop from the initial value of over 70° to virtually 0° in 0.5 s for the best fabricated membrane. The wetting properties of the membranes were studied by calculating the surface free energy by surface thermodynamic analysis, by evaluating the peak height ratio from Raman spectra, and other surface characterization methods. The superwettability phenomenon is the result of the synergetic effects of high surface free energy, the Wenzel model of wetting, and the crystalline phase of PVDF. Besides superwettability, the PVDF/PVDF- g -PEGMA membranes show great improvements in flux performance, sodium alginate (SA) rejection, and flux recovery upon fouling.

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“…All the developed PVDF-ENMs showed a randomly-oriented fibrous morphology. The polymer concentration played an important role in the morphology of the nanofibers, which is strictly related to the polymer solution viscosity [37]. In fact, at low polymer concentration, such as the case of M4 (Figure 2a,d), the nanofibers networks were heterogeneous and the formation of beads and non-uniform fibers was observed.…”

Section: Viscosity Meaurementmentioning

confidence: 98%

Innovative Poly (Vinylidene Fluoride) (PVDF) Electrospun Nanofiber Membrane Preparation Using DMSO as a Low Toxicity Solvent

et al. 2020

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Electrospinning is an emerging technique for the preparation of electrospun fiber membranes (ENMs), and a very promising one on the basis of the high-yield and the scalability of the process according to a process intensification strategy. Most of the research reported in the literature has been focused on the preparation of poly (vinylidene fluoride) (PVDF) ENMs by using N,N- dimethylformamide (DMF) as a solvent, which is considered a mutagenic and cancerogenic substance. Hence, the possibility of using alternative solvents represents an interesting approach to investigate. In this work, we explored the use of dimethyl sulfoxide (DMSO) as a low toxicity solvent in a mixture with acetone for the preparation of PVDF-ENMs. As a first step, a solubility study of the polymer, PVDF 6012 Solef®, in several DMSO/acetone mixtures was carried out, and then, different operating conditions (e.g., applied voltage and needle to collector plate distance) for the successful electrospinning of the ENMs were evaluated. The study provided evidence of the crucial role of solution conductivity in the electrospinning phase and the thermal post-treatment. The prepared ENMs were characterized by evaluating the morphology (by SEM), pore-size, porosity, surface properties, and performance in terms of water permeability. The obtained results showed the possibility of producing ENMs in a more sustainable way, with a pore size in the range of 0.2–0.8 µm, high porosity (above 80%), and water flux in the range of 11.000–38.000 L/m2·h·bar.

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Preparation of high strength poly(vinylidene fluoride) porous membranes with cellular structure via vapor-induced phase separation

Cited by 73 publications

References 32 publications

Polyvinylidene Fluoride Membrane Via Vapour Induced Phase Separation for Oil/Water Emulsion Filtration

Polyvinylidene Fluoride Membrane Via Vapour Induced Phase Separation for Oil/Water Emulsion Filtration

Superwettable PVDF/PVDF-g-PEGMA Ultrafiltration Membranes

Innovative Poly (Vinylidene Fluoride) (PVDF) Electrospun Nanofiber Membrane Preparation Using DMSO as a Low Toxicity Solvent

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