Production of calcium nitrate crystals via membrane distillation crystallization using polyvinylidene fluoride/sorbitan trioleate membranes

2021 ◽  
Vol 32 (5) ◽  
pp. 1463-1471
Author(s):  
Mohammad Nasiraee ◽  
Seyed Mahmoud Mousavi ◽  
Ehsan Saljoughi ◽  
Shirin Kiani ◽  
Kourosh Razmgar
Keyword(s):  
Polyvinylidene Fluoride ◽  
Calcium Nitrate ◽  
Membrane Distillation

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).

Superhydrophobic dual layer functionalized titanium dioxide/polyvinylidene fluoride- co -hexafluoropropylene (TiO 2 /PH) nanofibrous membrane for high flux membrane distillation

2017 ◽  
Vol 537 ◽  
pp. 140-150 ◽  
Author(s):  
Seyed Mahdi Seyed Shahabadi ◽  
Hesamoddin Rabiee ◽  
Seyed Mojtaba Seyedi ◽  
Amir Mokhtare ◽  
Jonathan A. Brant
Keyword(s):  
Titanium Dioxide ◽  
Polyvinylidene Fluoride ◽  
Membrane Distillation ◽  
Nanofibrous Membrane ◽  
High Flux

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.                                                                                               

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.

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