scholarly journals Membrane distillation of saline and oily water using nearly superhydrophobic PVDF membrane incorporated with SiO2 nanoparticles

2018 ◽  
Vol 78 (12) ◽  
pp. 2532-2541 ◽  
Author(s):  
N. Hamzah ◽  
M. Nagarajah ◽  
C. P. Leo
Keyword(s):  
Polyvinylidene Fluoride ◽  
Volume Ratio ◽  
Sio2 Nanoparticles ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
Oil And Grease ◽  
Sem Images ◽  
Water Contact ◽  
Pvdf Membrane ◽  
Oily Water

Abstract Fat, oil and grease in wastewater generated from household kitchens, restaurants and food processing plants affect sewer systems, water resources and environment adversely. Hence, membrane distillation of saline and oily water was studied using a nearly superhydrophobic membrane developed in this work. Polyvinylidene fluoride (PVDF) membrane incorporated SiO2 nanoparticles was synthesized via phase inversion with dual baths and modified using hexadecyltrimethoxy silane. The volume ratio of silane to ethanol was varied between 1:200 to 1:25. The membrane characteristics were examined using a goniometer, a porometer, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The PVDF-SiO2 membrane modified using the volume ratio of 1:50 achieved the highest water contact angle of 141.6° and LEP of 2.642 bar. This membrane was further tested in membrane distillation to observe the permeate flux of distilled water, saline solution (1 M NaCl) as well as saline and oily solution (1 M NaCl; 1,000 ppm of palm oil). The modified PVDF/SiO2 showed high permeate flux which is nearly four times of the permeate flux of neat PVDF membrane, but still susceptible of salt and oil fouling as shown in SEM images.

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 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.

Performance of Surface Modification of Polyvinylidene Fluoride Hollow Fiber Membrane in Membrane Distillation

2013 ◽  
Vol 795 ◽  
pp. 137-140 ◽  
Author(s):  
Kok Chung Chong ◽  
Soon Onn Lai ◽  
K.M. Lee ◽  
Woei Jye Lau ◽  
B.S. Ooi
Keyword(s):  
Hollow Fiber ◽  
Polyvinylidene Fluoride ◽  
Hollow Fiber Membrane ◽  
Skin Layer ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
Fiber Membrane ◽  
Water And Wastewater Treatment ◽  
Pvdf Membrane ◽  
Different Temperatures

Membrane distillation (MD) is one of the novel separation methods used in water and wastewater treatment processes. MD is a thermal driven process which has the potential to be integrated with renewable energy source and can be operated at very low pressure. Polyvinylidene fluoride (PVDF) is a hydrophobic polymeric material which is commonly used to prepare MD membrane. In this study, surface modifying macromolecule (SMM) was added as additive into PVDF dope solution and then the hollow fiber membrane was prepared using phase inversion process. The membrane was characterized with respect to morphology and permeates flux at different temperatures. The results revealed that the PVDF membrane blended with SMM exhibited higher permeate flux than PVDF neat membrane did, mainly due to the better pore size distribution and thinner skin layer. This finding indicated the role of SMM in modifying the properties of PVDF membrane for MD process.

scholarly journals Electrospun Nanostructured Membrane Engineering Using Reverse Osmosis Recycled Modules: Membrane Distillation Application

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1601
Author(s):  
Jorge Contreras-Martínez ◽  
Carmen García-Payo ◽  
Mohamed Khayet
Keyword(s):  
Reverse Osmosis ◽  
Polyvinylidene Fluoride ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
Electrospinning Technique ◽  
Salt Rejection ◽  
Rejection Factor ◽  
Nanofibrous Membranes ◽  
Membrane Engineering ◽  
Desalination Plants

As a consequence of the increase in reverse osmosis (RO) desalination plants, the number of discarded RO modules for 2020 was estimated to be 14.8 million annually. Currently, these discarded modules are disposed of in nearby landfills generating high volumes of waste. In order to extend their useful life, in this research study, we propose recycling and reusing the internal components of the discarded RO modules, membranes and spacers, in membrane engineering for membrane distillation (MD) technology. After passive cleaning with a sodium hypochlorite aqueous solution, these recycled components were reused as support for polyvinylidene fluoride nanofibrous membranes prepared by electrospinning technique. The prepared membranes were characterized by different techniques and, finally, tested in desalination of high saline solutions (brines) by direct contact membrane distillation (DCMD). The effect of the electrospinning time, which is the same as the thickness of the nanofibrous layer, was studied in order to optimize the permeate flux together with the salt rejection factor and to obtain robust membranes with stable DCMD desalination performance. When the recycled RO membrane or the permeate spacer were used as supports with 60 min electrospinning time, good permeate fluxes were achieved, 43.2 and 18.1 kg m−2 h−1, respectively; with very high salt rejection factors, greater than 99.99%. These results are reasonably competitive compared to other supported and unsupported MD nanofibrous membranes. In contrast, when using the feed spacer as support, inhomogeneous structures were observed on the electrospun nanofibrous layer due to the special characteristics of this spacer resulting in low salt rejection factors and mechanical properties of the electrospun nanofibrous membrane.

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 A Comparison Study of Brine Desalination using Direct Contact and Air Gap Membrane Distillation

2019 ◽  
Vol 25 (11) ◽  
pp. 47-54
Author(s):  
Ahmed Shamil Khalaf ◽  
Asrar Abdullah Hassan
Keyword(s):  
Flow Rate ◽  
Direct Contact ◽  
Polyvinylidene Fluoride ◽  
Membrane Distillation ◽  
Air Gap ◽  
Feed Flow Rate ◽  
Permeate Flux ◽  
Air Gap Membrane Distillation ◽  
Flat Sheet ◽  
Feed Temperature

Membrane distillation (MD) is a hopeful desalination technique for brine (salty) water. In this research, Direct Contact Membrane Distillation (DCMD) and  Air Gap Membrane Distillation (AGMD) will be used. The sample used is from Shat Al –Arab water (TDS=2430 mg/l). A polyvinylidene fluoride (PVDF) flat sheet membrane was used as a flat sheet form with a plate and frame cell. Several parameters were studied, such as; operation time, feed temperature, permeate temperature, feed flow rate. The results showed that with time, the flux decreases because of the accumulated fouling and scaling on the membrane surface. Feed temperature and feed flow rate had a positive effect on the permeate flux, while permeate temperature had a reverse effect on permeate flux. It is noticeable that the flux in DCMD is greater than AGMD, at the same conditions. The flux in DCMD is 10.95LMH, and that in AGMD is 7.14 LMH.  In AGMD, the air gap layer made a high resistance. Here the temperature transport reduces in the permeate side of AGMD due to the air gap resistance. The heat needed for AGMD is lower than DCMD, this leads to low permeate flux because the temperature difference between the two sides is very small, so the driving force (vapor pressure) is low.                                                                                               

scholarly journals Characterization of the Initial Fouling Layer on the Membrane Surface in a Membrane Bioreactor: Effects of Permeation Drag

Membranes ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 121
Author(s):  
Shengli Wang ◽  
Xin Lu ◽  
Lanhe Zhang ◽  
Jingbo Guo ◽  
Haifeng Zhang
Keyword(s):  
Zeta Potential ◽  
Electron Donor ◽  
Energy Barrier ◽  
Polyvinylidene Fluoride ◽  
Membrane Bioreactor ◽  
Membrane Surface ◽  
Permeate Flux ◽  
Pvdf Membrane ◽  
Operating Modes

In this study, the properties of the initial fouling layer on the membrane surface of a bioreactor were investigated under different operating modes (with or without permeate flux) to improve the understanding of the effect of permeation drag on the formation of the initial fouling layer. It was found that protein was the major component in the two types of initial fouling layers, and that the permeation drag enhanced the tryptophan protein-like substances. The attraction of the initial foulants to the polyvinylidene fluoride (PVDF) membrane was ascribed to the high zeta potential and electron donor component (γ−) of the membrane. Thermodynamic analyses showed that the permeation drag-induced fouling layer possessed high hydrophobicity and low γ−. Due to permeation drag, a portion of the foulants overcame an energy barrier before they contacted the membrane surface, which itself possessed a higher fouling propensity. A declining trend of the cohesive strength among the foulants was found with the increasing development of both fouling layers.

Filtration of crude canola oil miscella utilizing PVDF membrane: the effects of pretreatments and operating conditions

2012 ◽  
Vol 8 (3) ◽  
Author(s):  
Razieh Niazmand ◽  
Reza Farhoosh ◽  
Seyed Mohammad Ali Razavi
Keyword(s):  
Canola Oil ◽  
Polyvinylidene Fluoride ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Permeate Flux ◽  
Pvdf Membrane ◽  
Flat Membrane ◽  
Temperature And Pressure ◽  
Increasing Temperature ◽  
Membrane Cell

Abstract This study was conducted on adding chemical agents (aqueous solutions of CaCl2, EDTA and SDS) to crude canola oil miscella before ultrafiltration through polyvinylidene fluoride (PVDF) membrane with MWCO 50 kDa in a magnetically stirred flat membrane cell. Operating conditions including pressures 2-5 bar and temperatures 25-55 °C were employed. Permeate flux of pretreated oil samples exhibited sharp risings with increasing temperature and pressure. Except for the oils pretreated with SDS, the rejection of free fatty acids (FFAs) decreased in all oil samples. Increasing the operating pressure to 4 bar decreased the rejection of FFAs. Pretreatment of the oils with SDS and EDTA resulted in higher amounts of phosphorous rejection, while increasing temperature decreased it. Reduction of color values (L, a, and b) of the oil samples was not considerable through 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.      

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