scholarly journals A Morphological Study of Poly (Vinylidene Fluoride) Pvdf Membranes: In Perspective of Membrane Pervaporation Process

2015 ◽  
Vol 14 (2) ◽  
pp. 38
Author(s):  
Adil Hatem Rashid ◽  
M. D. Irfan Hatem ◽  
Muhammad Syarhabil Ahmad ◽  
Mohd. Hafiz Dzarfan Othman
Keyword(s):  
Contact Angle ◽  
Pore Size ◽  
Polyvinylidene Fluoride ◽  
Vinylidene Fluoride ◽  
Membrane Separation ◽  
Polymer Concentration ◽  
Inversion Method ◽  
Separation Processes ◽  
Pvdf Membrane ◽  
Wide Range

Membrane separation plays an important role in chemical industry (Prabhat et al. 2011). Pervaporation is one of the most promising membrane separation processes which is used in a wide range of applications such as separation of organic mixtures and dehydration of solvents. This study investigated the effect of polymer concentration on the morphology of pervaporation membrane, where polyvinylidene fluoride (PVDF) was chosen as the base polymeric material while phase inversion method was employed as a technique to prepare an asymmetric PVDF membrane. The polymer concentration in dope solution was varied from 16 to 20wt% and the prepared membranes were characterized in terms of its structure, porosity, contact angle, and pore size. Five PVDF membrane samples were prepared (without any post-treatment) with polymer concentration of 16, 17, 18, 19, and 20wt% respectively. Depending on permeating component, two main areas of pervaporation processes can be identified: hydrophobic and hydrophilic and consequently two types of membranes could be observed: hydrophobic and hydrophilic membranes. From the results, it was found that the increase in polymer concentration has produced membranes with low pore size and porosity and as a result, high contact angle (low hydrophilicity).The highest contact angle of 83º was found for membrane with highest polymer concentration of 20wt% with the lowest pore size and porosity of (0.4156µm and 65%) respectively. The lowest contact angle of 76º was found for membrane with the lowest polymer concentration of 16wt% with the highest pore size and porosity (0.8671µm and78%) respectively.

scholarly journals Effect of temperature and salt on PVDF membrane wetting properties

2021 ◽  
Author(s):  
Kefan Jiang ◽  
◽  
Hooman Chamani ◽  
Takeshi Matsuura ◽  
Dipak Rana ◽  
...  
Keyword(s):  
Contact Angle ◽  
Polyvinylidene Fluoride ◽  
Membrane Separation ◽  
Feed Solution ◽  
Membrane Distillation ◽  
Effect Of Temperature ◽  
Separation Processes ◽  
Water Contact ◽  
Pvdf Membrane ◽  
Wetting Properties

Membrane distillation (MD) is a thermally driven separation process. Despite many advantages over other membrane separation processes, pore wetting hampers the wide commercial applications of the MD process. In this paper, the effect of temperature and presence (or absence) of salt in the feed solution on the wetting properties of commercial polyvinylidene fluoride (PVDF) membrane during a period of eight weeks was investigated. Liquid entry pressure (LEP) and water contact angle (WCA) were employed to characterize the wetting properties of the PVDF membrane. The result shows that the temperature has a significant impact on the decrease of the contact angle of the PVDF membrane.

Characteristic and Performance of Polyvinylidene Fluoride Membranes Blended with Lithium Chloride in Direct Contact Membrane Distillation

2014 ◽  
Vol 69 (9) ◽  
Author(s):  
S. O. Lai ◽  
K. C. Chong ◽  
K. M. Lee ◽  
W. J. Lau ◽  
B. S. Ooi
Keyword(s):  
Lithium Chloride ◽  
Direct Contact ◽  
Polyvinylidene Fluoride ◽  
Membrane Separation ◽  
Polymeric Materials ◽  
Membrane Distillation ◽  
Inversion Method ◽  
Permeate Flux ◽  
Separation Processes ◽  
Direct Contact Membrane Distillation

Membrane distillation (MD) is one of the recent rising membrane separation techniques adopted in the desalination and wastewater treatment. Unlike other pressure-driven separation processes such as reverse osmosis and nanofiltration, MD is a thermal-driven process which involves vapor pressure difference across the feed and permeates solutions. As such, MD requires low energy consumption. Hydrophobic polymeric materials such as polyvinylidene fluoride (PVDF) are frequently used in direct contact membrane distillation (DCMD) due to low surface energy and promising thermal resistance. In this study, the DCMD hollow fiber membranes were separately prepared with PVDF and PVDF blended with lithium chloride (LiCl) through dry/wet phase inversion method. Subsequently, the membranes were used in a DCMD process to remove sodium chloride (NaCl) under different feed inlet temperatures to examine the effect of LiCl additives on the neat membrane. The result showed that by adding LiCl into the neat membrane solution, the finger-like structure was change to a sponge-like structure with microvoids. Furthermore, the performance of the LiCl additive membrane in term of permeate flux was found to be 20% higher compared to that of the neat membrane. Other results of the membrane characteristics were also discussed.      

Cellulose acetate and polyvinylidene fluoride nanofiber mats for N95 respirators

2019 ◽  
pp. 152808371985876 ◽  
Author(s):  
C Akduman
Keyword(s):  
Pore Size ◽  
Cellulose Acetate ◽  
Polyvinylidene Fluoride ◽  
Polymer Concentration ◽  
Mean Flow ◽  
Bubble Point ◽  
Nanofiber Diameter ◽  
Wide Range ◽  
Small Pore ◽  
Nanofiber Mats

Nanofibrous media have a low basis weight, high permeability and small pore size that make them appropriate for a wide range of filtration applications, particularly for smaller particles. In contrast to electrostatic filter media, nanofibers' filtration efficiencies depend on the mechanical filtration mechanism and do not degrade with time. In this study, the National Institute for Occupational Safety and Health (NIOSH) requirements for the N95 particulate filtering half mask were achieved using electrospun cellulose acetate (CA) and polyvinylidene fluoride (PVDF) nanofiber coated polypropylene spunbond layers. Specifically, 16 and 15% (w/v), and 14, 12 and 10% (w/w) polymer concentrations were selected for CA nanofibers and PVDF nanofibers, respectively, to adjust the nanofiber diameters. The diameters of CA and PVDF nanofibers were decreased with decreasing polymer concentration for both CA (319.02 to 264.02 nm) and PVDF (236.50 to 142.59 nm) nanofibers. The thickness of the electrospun 16CA, 15CA and 14PVDF, 12PVDF, 10PVDF mats was adjusted by varying the collection period (15 min, 30 min, 60 min). The effects of electrospun CA and PVDF nanofiber diameter on the pore size and the thickness of the mats were compared in terms of filtration performance. 16CA with a nanofiber diameter of 319.02 nm had the largest first bubble point of 26.5 µm and mean flow pore size of 5.71 µm at 15 min with a thickness of 0.019 mm. The smallest first bubble point and mean flow pore values and the smallest pore size were achieved with the finest nanofibers of 10PVDF. Filtration performances were given as initial penetration and air flow resistance (ΔP). 16CA-60 min and 15CA-30 min mats both met the NIOSH requirements with their bulky structure. For PVDF, thinner nanofibers with smaller pores were produced compared to the CA nanofibers, and the NIOSH requirements were only achieved using double-layered, face-to-face 10PVDF-15 min nanofiber mats with the penetration of 1.85% and ΔP of 33.87 mmH2O.

Application of the ceramic membrane with hydrophobic skin layer to separation of activated sludge

1997 ◽  
Vol 35 (8) ◽  
pp. 137-144 ◽  
Author(s):  
Tsuyoshi Nomura ◽  
Takao Fujii ◽  
Motoyuki Suzuki
Keyword(s):  
Activated Sludge ◽  
Pore Size ◽  
Ceramic Membrane ◽  
Membrane Separation ◽  
Porous Ceramic ◽  
Porous Membrane ◽  
Skin Layer ◽  
Gas Permeation ◽  
Wide Range ◽  
Cake Layer

Porous membrane of poly(tetrafluoroethylene) (PTFE) was formed on the surface of porous ceramic tubes by means of heat treatment of the PTFE particles deposit layer prepared by filtering PTFE microparticles emulsified in aqueous phase. By means of inert gas permeation, pore size was determined and compared with scanning electron micrograph observation. Also rejection measurement of aqueous dextran solutions of wide range of molecular weights showed consistent results regarding the pore size. Since the membrane prepared by this method is stable and has unique features derived from PTFE, it is expected that the membrane has interesting applications in the field of water treatment. Membrane separation of activated sludge by this composite membrane and original ceramics membrane showed that the PTFE membrane gives better detachability of the cake layer formed on the membrane. This might be due to the hydrophobic nature of the PTFE skin layer.

scholarly journals The Modification of PVDF Membrane via Crosslinking with Chitosan and Glutaraldehyde as the Crosslinking Agent

2018 ◽  
Vol 18 (1) ◽  
pp. 1
Author(s):  
Romaya Sitha Silitonga ◽  
Nurul Widiastuti ◽  
Juhana Jaafar ◽  
Ahmad Fauzi Ismail ◽  
Muhammad Nidzhom Zainol Abidin ◽  
...  
Keyword(s):  
Contact Angle ◽  
Vinylidene Fluoride ◽  
Membrane Surface ◽  
Pure Water ◽  
Water Flux ◽  
Crosslinking Agent ◽  
Hydrophobic Properties ◽  
Pvdf Membrane ◽  
Pure Water Flux ◽  
Modified Membrane

Poly(vinylidene fluoride) (PVDF) has outstanding properties such as high thermal stability, resistance to acid solvents and good mechanical strength. Due to its properties, PVDF is widely used as a membrane matrix. However, PVDF membrane is hydrophobic properties, so as for specific applications, the surface of membrane needs to be modified to become hydrophilic. This research aims to modify PVDF membrane surface with chitosan and glutaraldehyde as a crosslinker agent. The FTIR spectra showed that the modified membrane has a peak at 1655 cm-1, indicating the imine group (–N=C)- that was formed due to the crosslink between amine group from chitosan and aldehyde group from glutaraldehyde. Results showed that the contact angle of the modified membrane decreases to 77.22° indicated that the membrane hydrophilic properties (< 90°) were enhanced. Prior to the modification, the contact angle of the PVDF membrane was 90.24°, which shows hydrophobic properties (> 90°). The results of porosity, Ɛ (%) for unmodified PVDF membrane was 55.39%, while the modified PVDF membrane has a porosity of 81.99%. Similarly, by modifying the PVDF membrane, pure water flux increased from 0.9867 L/m2h to 1.1253 L/m2h. The enhancement of porosity and pure water flux for the modified PVDF membrane was due to the improved surface hydrophilicity of PVDF membrane.

scholarly journals The influences of polydopamine immersion time on characteristics and performance of polyvinylidene fluoride ultrafiltration membrane

2018 ◽  
Vol 197 ◽  
pp. 09007
Author(s):  
Syawaliah Syawaliah ◽  
Nasrul Arahman ◽  
Medyan Riza ◽  
Sri Mulyati
Keyword(s):  
Polyvinylidene Fluoride ◽  
Water Flux ◽  
Sem Analysis ◽  
Inversion Method ◽  
Asymmetric Structure ◽  
Pvdf Membrane ◽  
Before And After ◽  
Poly Ethylene ◽  
And Performance ◽  
Phase Inversion Method

The Polyvinylidene Fluoride (PVDF) membrane has been prepared by phase inversion method using N,N-dimethylacetamide (DMAc) as solvent and Poly Ethylene Glycol (PEG) as additive. The fabricated membrane was modified by Polydopamine (PDA) coating in concentration of 0.5 mg/ml and immersion times of 2 hours, 6 hours, and 24 hours. The characteristics and performance of the PVDF membranes before and after the modification are studied in this paper. The result of the water flux experiment showed that the PDA-coated PVDF membranes showcased a higher flux than that of pure PVDF membrane. Scanning Electron Microscopy (SEM) analysis confirmed that the membrane had an asymmetric structure consisting of two layers. There was no significant influence on the addition of PDA to the morphology of the pore matrix because the modification was done by surface coating. Fourier Transform Infrared Spectroscopy (FTIR) analysis showed that PDA was successfully introduced on the surface of PVDF membrane with the appearance of O-H from cathecol and N-H peaks at wavenumber range of 3300-3600 cm-1. Modification with PDA increased the mechanical strength of the membrane which affirmed by the results of the tensile and elongation at break evaluation.

scholarly journals Preparation and Characterization of TiO2-PVDF/PMMA Blend Membranes Using an Alternative Non-Toxic Solvent for UF/MF and Photocatalytic Application

Molecules ◽  
2019 ◽  
Vol 24 (4) ◽  
pp. 724 ◽  
Author(s):  
Ouassila Benhabiles ◽  
Francesco Galiano ◽  
Tiziana Marino ◽  
Hacene Mahmoudi ◽  
Hakim Lounici ◽  
...  
Keyword(s):  
Phase Separation ◽  
Vinylidene Fluoride ◽  
Membrane Surface ◽  
Polymer Concentration ◽  
Inversion Method ◽  
Membrane Morphology ◽  
Photocatalytic Application ◽  
Poly Vinylidene Fluoride ◽  
Dope Solution ◽  
Phase Inversion Method

The approach of the present work is based on the use of poly (methylmethacrylate) (PMMA) polymer, which is compatible with PVDF and TiO2 nanoparticles in casting solutions, for the preparation of nano-composites membranes using a safer and more compatible solvent. TiO2 embedded poly (vinylidene fluoride) (PVDF)/PMMA photocatalytic membranes were prepared by phase inversion method. A non-solvent induced phase separation (NIPS) coupled with vapor induced phase separation (VIPS) was used to fabricate flat-sheet membranes using a dope solution consisting of PMMA, PVDF, TiO2, and triethyl phosphate (TEP) as an alternative non-toxic solvent. Membrane morphology was examined by scanning electron microscopy (SEM). Backscatter electron detector (BSD) mapping was used to monitor the inter-dispersion of TiO2 in the membrane surface and matrix. The effects of polymer concentration, evaporation time, additives and catalyst amount on the membrane morphology and properties were investigated. Tests on photocatalytic degradation of methylene blue (MB) were also carried out using the membranes entrapped with different concentrations of TiO2. The results of this study showed that nearly 99% MB removal can be easily achieved by photocatalysis using TiO2 immobilized on the membrane matrix. Moreover, it was observed that the quantity of TiO2 plays a significant role in the dye removal.

Novel Nanoparticles Incorporated Polyvinylidene Fluoride Ultrafiltration Membrane

2013 ◽  
Vol 746 ◽  
pp. 390-393
Author(s):  
Qiong Zhi Gao ◽  
Hong Qiang Li ◽  
Xing Rong Zeng
Keyword(s):  
Polyvinylidene Fluoride ◽  
Phase Inversion ◽  
Water Flux ◽  
Silver Ions ◽  
Inversion Method ◽  
Hybrid Films ◽  
Ultrafiltration Membranes ◽  
Pvdf Membrane ◽  
Basic Performance ◽  
Phase Inversion Method

In this study, polyvinylidene fluoride (PVDF) composite ultrafiltration membranes were prepared by a phase inversion method, N,N-dimethylacetamide (DMAc) was used as solvent and polyvinylpyrrolidone (PVP) was used as dispersant, nanoTiO2 and AgNO3 were used as addictive materials. With different doping content of nanoTiO2 and silver ions, those hybrid films have different functions and structure. The basic performance and photocatalytic properties of those ultrafiltration membranes were studied in detail. The experiment results show that adding nanosized TiO2 particles will make the porosity of PVDF membrane increase, adding silver ion with low content can not improve water flux and porosity of membranes, however, nanoTiO2 and silver ions doping together can effectively improve the photocatalytic degradation rate.

scholarly journals Membrane distillation crystallization using PVDF membrane incorporated with TiO2 nanoparticles and nanocellulose

2020 ◽  
Vol 20 (5) ◽  
pp. 1629-1642 ◽  
Author(s):  
Hoi-Fang Tan ◽  
Why-Ling Tan ◽  
N. Hamzah ◽  
M. H. K. Ng ◽  
B. S. Ooi ◽  
...  
Keyword(s):  
Pore Size ◽  
Tio2 Nanoparticles ◽  
Polyvinylidene Fluoride ◽  
Phase Inversion ◽  
Membrane Distillation ◽  
Coagulation Bath ◽  
Membrane Thickness ◽  
Permeate Flux ◽  
Sem Images ◽  
Pvdf Membrane

Abstract Polyvinylidene fluoride (PVDF) membrane was improved using TiO2 nanoparticles and nanocellulose for membrane distillation crystallization in this work. Besides the addition of TiO2 nanoparticles and nanocellulose, PVDF membrane was post-modified with octadecyltrichlorosilane after phase inversion using a dual coagulation bath. The addition of hydrophilic TiO2 nanoparticles and nanocellulose reduced membrane hydrophobicity, but the dispersed TiO2 nanoparticles assisted silane modification to improve surface hydrophobicity. Besides reducing the agglomeration of TiO2 nanoparticles, nanocellulose induced the formation of larger pore size and higher porosity as proven in SEM images and gravimetric measurement, respectively. The abundant moieties of nanocellulose accelerated the exchange between solvent and non-solvent during phase inversion for the formation of large pore size and porosity, but membrane thickness increased due to the thickening effects. The modified membrane showed higher water permeate flux in membrane distillation with salt rejection greater than 97%. Severe fouling in membrane distillation crystallization was not observed.

scholarly journals Improved salt rejection, hydrophilicity and mechanical properties of novel thermoplastic polymer/chitosan nanofibre membranes

2020 ◽  
Vol 15 ◽  
pp. 155892502092317
Author(s):  
Fahad S Al-Mubaddel ◽  
Hamad S AlRomaih ◽  
Mohammad Rezaul Karim ◽  
Monis Luqman ◽  
Maher M Al-Rashed ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Contact Angle ◽  
Polyvinylidene Fluoride ◽  
Phase Inversion ◽  
Water Flux ◽  
Tensile Tests ◽  
Membrane Properties ◽  
Inversion Method ◽  
Thermoplastic Polymer ◽  
Salt Rejection

The present study reports on the preparation of novel nanofibre membranes from the thermoplastic polymer polyvinylidene fluoride coated with chitosan to enhance membrane properties such as hydrophilicity, mechanical properties, water flux and salt rejection. Initially, a supporting layer was produced from polyvinylidene fluoride using phase inversion methods, followed by being coated with chitosan using either electrospinning or immersion methods. Two types of fabricated membranes with different coating methods were characterized and tested for physical and chemical performance using field-emission scanning electron microscopy, tensile tests, permeation tests (water flux and salt rejection) and contact angle measurements. It was found that the support membrane (polyvinylidene fluoride) produced by the phase inversion method that was coated with chitosan using electrospinning showed better performance, with a salt rejection up to 70% for MgSO4, a decreased the contact angle (52°) and improved the elongation at the breaking point (~82%).

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