scholarly journals Exploiting the Interplay between Liquid-Liquid Demixing and Crystallization of the PVDF Membrane for Membrane Distillation

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
N. I. M. Nawi ◽  
M. R. Bilad ◽  
N. A. H. M. Nordin ◽  
M. O. Mavukkandy ◽  
Z. A. Putra ◽  
...  
Keyword(s):  
Polyvinylidene Fluoride ◽  
Water Flux ◽  
High Water ◽  
Membrane Distillation ◽  
Degree Of Crystallinity ◽  
Solution Temperature ◽  
Hydrophobic Membrane ◽  
Sem Images ◽  
Cold Temperatures ◽  
Dope Solution

Membrane distillation (MD) purifies water by transporting its vapor through a hydrophobic membrane. An ideal MD membrane poses high water flux and high fouling, scaling, and wetting resistances. In this study, we develop polyvinylidene fluoride (PVDF) membranes for MD by focusing on reduction of PVDF degree of crystallinity. We explore the roles of dope solution temperature in dictating the phase separation mechanisms as well as the structure and the performance of semicrystalline PVDF membranes. DSC spectra show that higher dope solution temperature depresses crystallinity via formation of imperfect crystal. Such findings were also supported by FTIR and XRD results. The SEM images reveal formation of spherulite-like morphology in the membrane matrices for membranes prepared from high temperature dope solutions. A good balance between solid-liquid and liquid-liquid phase separations that offers low degree of crystallinity was found at a dope solution temperature of 60°C (PVDF-60), which showed the MD flux of 18 l/m2 h (vs. 6 l/m2 h for temperature of 25°C, as a benchmark) and nearly complete salt rejection when run at hot and cold temperatures of 65°C and 25°C, respectively. The PVDF-60 shows a high wetting resistance and stable MD flux of 10.5 l/m2 h over a 50 h test for treating brine solution as the feed (70 g NaCl/l).

scholarly journals Desalination by Membrane Distillation Using Electrospun Membranes

2019 ◽  
Vol 26 (1) ◽  
pp. 35-42
Author(s):  
Mustafa Hussein Al-Furaiji ◽  
Khairi R Kalash
Keyword(s):  
Polyvinylidene Fluoride ◽  
High Performance ◽  
Water Flux ◽  
Feed Solution ◽  
High Water ◽  
Membrane Distillation ◽  
Electrospinning Process ◽  
Nanofiber Membrane ◽  
Electrospun Membranes ◽  
Highly Porous

Electrospinning is a novel technique that can be used to produce highly porous fibers with highly tunable properties. In this research, this technique is adopted to prepare the electrospun nanofiber membrane for membrane distillation application. A custom-built electrospinning setup was made to prepare the nanofibers membrane. Polyvinylidene fluoride (PVDF) polymer was used in the electrospinning process due to its high hydrophobicity. Electrospun (PVDF) nanofibers were tested in direct contact membrane distillation (DCMD) process using 0.6 M sodium chloride as a feed solution. The resulting nanofiber membrane exhibited high performance in DCMD (i.e. relatively high water flux and high salt rejection). It has been found that the prepared membrane has a uniform and fibrous structure as indicated by the scanning electron microscopy (SEM). Relatively thin fibers with a diameter of 250 nm were produced during the Electrospinning process.

scholarly journals Triple-Layer Nanofiber Membranes for Treating High Salinity Brines Using Direct Contact Membrane Distillation

Membranes ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 60 ◽  
Author(s):  
Mustafa Al-Furaiji ◽  
Jason T. Arena ◽  
Jian Ren ◽  
Nieck Benes ◽  
Arian Nijmeijer ◽  
...  
Keyword(s):  
Direct Contact ◽  
Polyvinylidene Fluoride ◽  
Water Flux ◽  
Feed Solution ◽  
High Water ◽  
Membrane Distillation ◽  
Pvdf Membrane ◽  
Direct Contact Membrane Distillation ◽  
Triple Layer ◽  
Layer Membrane

A composite, three-layered membrane for membrane distillation was prepared from electrospun polyvinylidene fluoride (PVDF) nanofibers supported by commercial polyethersulfone (PES) nanofiber based nonwoven from E.I. duPont de Nemours company (DuPont). The membranes were tested in direct contact membrane distillation (DCMD) using a 5.0 M sodium chloride brine as a feed solution. The triple layer membrane combines the hydrophobicity of PVDF and the robustness of the PES. The triple layer membrane demonstrated excellent performance in DCMD (i.e., relatively high water flux compared to the commercial PVDF membrane and a complete salt rejection of the brine) with mechanical properties imparted by the PES layer. This work is the first to demonstrate the use of a commercially produced nanofiber nonwoven for membrane distillation.

Morphological Study of Fabricated PVDF Based Hydrophobic Membrane for Different Additives and Coagulation Bath Temperature

2021 ◽  
Vol 18 (3) ◽  
pp. 39-47
Author(s):  
Meenakshi Yadav ◽  
Sushant Upadhyaya ◽  
Kailash Singh ◽  
Manish Vashishtha
Keyword(s):  
Contact Angle ◽  
Water Content ◽  
Temperature Difference ◽  
Synergistic Effects ◽  
Weight Percent ◽  
Membrane Distillation ◽  
Coagulation Bath ◽  
Hydrophobic Membrane ◽  
Sem Micrograph ◽  
Dope Solution

The demand of membrane distillation (MD) has increased since last few decades for numerous applications. The membrane used in MD is hydrophobic; therefore, the focus has been emphasised on the development of a suitable membrane with desired microstructure. In this study, the flat sheet hydrophobic membrane of suitable properties has been casted with various additives such as water, ethane-di-ol, and propan-2-ol in dope solution using a non-solvent induced phase separation (NIPS) technique. The effect of water content in dope solution has been studied on casted membrane porosity and contact angle. The maximum contact angle and porosity were found to be 96° and 53.23% at 4 weight percent of water content in dope solution of PVDF polymer and di.methyl.acetamide as solvent. It was found that SEM micrograph when ethane-di-ol and propan-2-ol are used as an additive shows more finger-like pores and nodules, respectively, in the microstructure of the casted membrane. Furthermore, synergistic effects using water with other additives were also identified using SEM micrograph of casted membrane and it was observed that water with ethane-di-ol and propan-2-ol form contact angle of 98° and 105°, respectively, for 2 weight percent each additive in dope. In this study, the membrane was also cast by dissolving PVDF powder in di.methyl.acetamide solvent with lithium chloride and the effect of the temperature difference between coagulation bath and film temperature was investigated using an SEM micrograph. Overall, it was found that water content and temperature difference aid in developing hydrophobic porous membrane of desired properties for MD applications.

Development of Nano-Carbon Bucky-Paper Membranes for Membrane Distillation

2012 ◽  
Vol 724 ◽  
pp. 408-411 ◽  
Author(s):  
Jae Wuk Koo ◽  
Ji Hee Han ◽  
Sang Ho Lee ◽  
Jin Sik Sohn ◽  
June Seok Choi
Keyword(s):  
Polyvinylidene Fluoride ◽  
Membrane Distillation ◽  
Practical Implementation ◽  
Vapor Permeability ◽  
Feed Water ◽  
Hydrophobic Membrane ◽  
Salt Rejection ◽  
Multi Stage ◽  
And Performance ◽  
Bucky Paper

Membrane distillation (MD) is a special evaporation process to produce fresh water from seawater or contaminated water using membranes. MD has advantages over other evaporation technologies such as multi-stage flash vaporization (MSF) and multi-effect distillation (MED) due to its relatively low energy requirements, allowing the use of solar energy as its heat source. Nevertheless, lack of membrane materials for MD process hinders its practical implementation for desalination and water treatment. In this study, membranes made of carbon nanotube (CNT) are presented for MD. Flat sheet hydrophobic membranes made of polyvinylidene fluoride (PVDF) were selected as supports for bucky-paper membranes, allowing formation of CNT bucky-paper without chemical reactions. Laboratory-scale systems were used to evaluate their potential and performance in direct contact MD. Water permeability and salt rejection were analyzed for each case. D.I water and synthetic feed water were used for the lab-scale tests. It was demonstrated that the physical immobilization of CNT on a hydrophobic membrane changed led to an increase in vapor permeability while improving salt rejection.

Dual layer hollow fiber PVDF ultra-filtration membranes containing Ag nano-particle loaded zeolite with longer term anti-bacterial capacity in salt water

2016 ◽  
Vol 73 (9) ◽  
pp. 2159-2167 ◽  
Author(s):  
Huyan Shi ◽  
Lixin Xue ◽  
Ailin Gao ◽  
Qingbo Zhou
Keyword(s):  
Hollow Fiber ◽  
Polyvinylidene Fluoride ◽  
Sea Water ◽  
Hollow Fiber Membrane ◽  
Salt Water ◽  
Water Flux ◽  
Composite Membranes ◽  
High Water ◽  
Nano Particles ◽  
Ultra Filtration

Dual layer polyvinylidene fluoride (PVDF), antibacterial, hollow fiber, ultra-filtration composite membranes with antibacterial particles (silver (Ag) nano-particles loaded zeolite (Z-Ag)) in the outer layer were prepared with high water flux and desired pore sizes. The amounts of Ag+ released from the composite membranes, freshly made and stored in water and salt solution, were measured. The result indicated that dual layer PVDF antibacterial hollow fiber containing Z-Ag (M-1-Ag) still possessed the ability of continuous release of Ag+ even after exposure to water with high ionic content, showing a longer term resistance to bacterial adhesion and antibacterial activity than membrane doped with Z-Ag+ (M-1). Results from an anti-adhesion and bacteria killing test with Escherichia coli supported that the antibacterial efficiency of dual hollow fiber PVDF membranes with Z-Ag was much higher than those with Z-Ag+ after long time storage in water or exposure to phosphate buffered saline (PBS) solution. This novel hollow fiber membrane may find applications in constructing sea water pretreatment devices with long term antifouling capability for the desalination processes.

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.

A Novel Polyethersulfone Flat Sheet Membrane Prepared from a Lower Critical Solution Temperature System

2012 ◽  
Vol 538-541 ◽  
pp. 29-32
Author(s):  
Jing Diao ◽  
Jian Feng Xu ◽  
Song Tao Li ◽  
Xiao Hui Cao ◽  
Chun Yi Liu ◽  
...  
Keyword(s):  
Lower Critical Solution Temperature ◽  
Pure Water ◽  
Water Flux ◽  
Bath Temperature ◽  
Solution Temperature ◽  
Coagulation Bath ◽  
Sem Images ◽  
Critical Solution Temperature ◽  
Flat Sheet ◽  
Flat Sheet Membrane

Polyethersulfone (PES) flat sheet membranes were prepared via phase inversion induced by immersion precipitation from a novel lower critical solution temperature (LCST) system containing PES, 1-butanol and N, N-dimethylacetamide. And the effect of coagulation bath temperature on the properties and structure of PES membranes were investigated. The results show that the pure water flux increases and the tensile strength decreases as the coagulation temperature increases form 20°C to 50°C. Besides, the SEM images shows that all of the membranes prepared from a LCST system at different CBT own sponge-like structures.

Synthesis and Characterization of CTA/CA-Based Forward Osmosis Membranes with Hydrophilic Nano-Titanium Dioxide

2016 ◽  
Vol 867 ◽  
pp. 127-131 ◽  
Author(s):  
Xiu Ju Wang ◽  
Xin Lian Shi ◽  
Shu Fang Hou ◽  
Jian Hua Yang ◽  
Kai Li Zhou ◽  
...  
Keyword(s):  
Pure Water ◽  
Water Flux ◽  
Forward Osmosis ◽  
Bath Temperature ◽  
High Water ◽  
Cellulose Triacetate ◽  
Sem Images ◽  
Salt Rejection ◽  
Pure Water Flux ◽  
Nano Titanium Dioxide

In this paper, a novel nanocomposite forward osmosis membrane (nTiO2-CTA/CA) was fabricated by introducing nanotitaniumdi oxide (nTiO2) into the cellulose triacetate/cellulose acetate (CTA/CA)-based casting solution using phase inversion methods. Casting composite and preparation--nTiO2 content, blend temperature and coagulating bath temperature--were tested for their effects on pure water flux and salt rejection of membranes. Results revealed that the FO membrane prepared under optimized composition showed excellent desalination performance (high water flux = 5.38 L/m2·h and salt rejection > 97 %). Moreover, SEM images showed that addition of nTiO2 resulted in nanocomposite forward osmosis membrane with a smoother surface. The contact angle of the membranes decreased from 76o to 51° with increase nTiO2 concentration from 0% to 0.10%.

One-step nanotopography construction by polyaniline polymerization for a superhydrophobic nanofibrous membrane towards direct contact membrane distillation

2019 ◽  
Vol 6 (8) ◽  
pp. 2553-2564 ◽  
Author(s):  
Lingling Zhong ◽  
Zhigao Zhu ◽  
Yu Han ◽  
Qiao Wang ◽  
Dongmei Liu ◽  
...  
Keyword(s):  
Direct Contact ◽  
Water Flux ◽  
High Water ◽  
Membrane Distillation ◽  
Nanofibrous Membrane ◽  
Direct Contact Membrane Distillation ◽  
One Step ◽  
Nanofibrous Membranes

In situ polymerization of aniline is used to prepare superhydrophobic PVDF nanofibrous membranes for direct contact membrane distillation with high water flux and long wetting times.

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