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.

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 contact angle study of different greywater sources with hydrophobic membranes

2020 ◽  
Vol 55 (3) ◽  
pp. 310-326
Author(s):  
Mohammad Ramezanianpour ◽  
Muttucumaru Sivakumar ◽  
Natalie Osborn ◽  
Ying Zhang ◽  
Hakim Kawa
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Pure Water ◽  
Membrane Distillation ◽  
Hydrophobic Membrane ◽  
Flat Sheet ◽  
Hydrophobic Membranes ◽  
Different Types ◽  
The Impact ◽  
Surface Tension Forces

Abstract The wetting phenomenon is a major problem in the membrane distillation (MD) process, and it is the main reason that limits MD being used in wastewater reclamation. Active surfactant in the detergents reduces the contact angle between the liquid and the hydrophobic membrane surface, which could result in wetting. Extensive laboratory research was conducted using commercial hydrophobic flat-sheet membranes to identify the impact of anionic surfactants and surface tension forces on these membranes. The aim of this paper is to find a suitable membrane for pure water production from greywater using MD, as well as to provide a relationship between surfactant concentration and the contact angle for different types of membrane. The absorbance of each sample was measured by a spectrophotometer prior to the contact angle test on four different types of hydrophobic membranes. It was concluded that the polypropylene membrane would be unsuitable for the treatment of greywater directly due to the loss of surface tension forces upon the addition of an anionic surfactant. However, the polytetrafluoroethylene membrane could be effective in this process while the concentration of surfactant in the feed source is kept constant. The results from the experimental tests proposed a relationship between the contact angle of a water droplet on the surface of a flat-sheet membrane and the concentration of surfactant in the solution.

scholarly journals Modeling and Simulation of Fabricated Graphene Nanoplates/Polystyrene Nanofibrous Membrane for DCMD

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2987 ◽  
Author(s):  
Ahmad Abdullah ◽  
Abdulaziz Al-Qahatani ◽  
Mohammed Alquraish ◽  
Colin Bailey ◽  
Ahmed El-Shazly ◽  
...  
Keyword(s):  
Contact Angle ◽  
Composite Membrane ◽  
Pure Water ◽  
Weight Percent ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Hot Water ◽  
Hydrophobic Nature ◽  
Porosity Characterization ◽  
Graphene Nanoplates

Membrane distillation is an active technique that provides pure water with very good rejection and could be applied to water of extremely high salinity. The low productivity of membrane distillation needs intensive efforts to be competitive with other desalination techniques. In this current study, a composite (PS/GNP) membrane, which is composed of polystyrene (PS) based and 0.25% weight percent graphene nanoplates (GNP) has been fabricated via electrospinning and compared with the blank PS membrane. SEM, FTIR, contact angle and porosity characterization have been performed, and the results show that the validity of the predefined conditions, and the contact angle of the composite membrane, which is found to be 91.68°, proved the hydrophobic nature of the composite membrane. A numerical simulation using Ansys 2020 software has been introduced to study the performance of the fabricated composite membrane when used in direct contact membrane distillation (DCMD). The numerical model has been validated with experimental work from the literature and showed an excellent match. The blank PS and composite PS/GNP membranes have been investigated and compared at different operating conditions, i.e., hot water supply temperature and system flow rate. The results show that the composite PS/GNP membrane outperforms the blank PS membrane at all studied operating conditions.

Effect of Hydrophobicity Degree on PVDF Hollow Fiber Membranes for Textile Wastewater Treatment Using Direct Contact Membrane Distillation

2013 ◽  
Vol 65 (4) ◽  
Author(s):  
N. M. Mokhtar ◽  
W. J. Lau ◽  
P. S. Goh
Keyword(s):  
Contact Angle ◽  
Hollow Fiber ◽  
Direct Contact ◽  
Polyvinylidene Fluoride ◽  
Textile Wastewater ◽  
Membrane Distillation ◽  
Hollow Fiber Membranes ◽  
Hydrophobic Membrane ◽  
Direct Contact Membrane Distillation ◽  
Fiber Membranes

The objectives of this study are to study the effect of hydrophobicity degree of  polyvinylidene fluoride (PVDF) hollow fiber membranes blended with different types of additives i.e. ethylene glycol (EG) and polyvinylpyrrolidone (PVP) on textile wastewater application. The degree of hydrophobicity of each membrane was analyzed using contact angle goniometer. The membrane morphology and gas permeability were characterized prior to filtration experiment. Both membranes were tested using direct contact membrane distillation (DCMD) system and their performances were evaluated with respect to water flux and dye removal. This study revealed that the membrane with higher contact angle has greater stability in terms of flux and dye rejection compared to the membrane with low hydrophobic property. This is mainly due to the low surface energy obtained by the highly hydrophobic membrane that prevented the liquids from both sides to penetrate through membrane pores.

Coupled Phenomena Membrane Distillation and Osmotic Distillation through a Porous Hydrophobic Membrane

1995 ◽  
Vol 30 (6) ◽  
pp. 993-1011 ◽  
Author(s):  
M. P. Godino ◽  
L. Peña ◽  
J. M. Ortiz De Zárate ◽  
J. I. Mengual
Keyword(s):  
Membrane Distillation ◽  
Hydrophobic Membrane ◽  
Osmotic Distillation

scholarly journals A Simple Method to Create Superhydrophobic Aluminium Surfaces

2012 ◽  
Vol 706-709 ◽  
pp. 2874-2879 ◽  
Author(s):  
R. Jafari ◽  
Masoud Farzaneh
Keyword(s):  
Contact Angle ◽  
Stearic Acid ◽  
Synergistic Effects ◽  
Low Cost ◽  
Contact Angle Hysteresis ◽  
Spray Coating ◽  
Superhydrophobic Surfaces ◽  
Water Contact ◽  
Simple Method ◽  
Static Contact

Superhydrophobic surfaces were prepared using a very simple and low-cost method by spray coating. A high static water contact angle of about 154° was obtained by deposition of stearic acid on an aluminium alloy. However, this coating demonstrated a high contact angle hysteresis (~ 30º). On the other hand, superhydrophobic surfaces with a static contact angle of about 162º and 158º, and a low contact angle hysteresis of about 3º and 5º were respectively obtained by incorporating nanoparticles of SiO2and CaCO3in stearic acid. The excellent resulting hydrophobicity is attributed to the synergistic effects of micro/nanoroughness and low surface energy. A study of the wettability of these surfaces at temperatures ranging from 20 to-10 °C showed that the superhydrophobic surface becomes rather hydrophobic at supercooled temperatures.

scholarly journals Analysis and optimization of a new cylindrical air gap membrane distillation system

2019 ◽  
Vol 20 (1) ◽  
pp. 361-371 ◽  
Author(s):  
Vandita T. Shahu ◽  
S. B. Thombre
Keyword(s):  
Flow Rate ◽  
Membrane Separation ◽  
Negative Impact ◽  
Membrane Distillation ◽  
Air Gap ◽  
Cylindrical Shape ◽  
Hydrophobic Membrane ◽  
Tube Heat Exchanger ◽  
Whole Process ◽  
Air Gap Membrane Distillation

Abstract Membrane distillation is a rate-governed non-isothermal membrane separation technique that utilizes trans-membrane temperature difference for evaporating water and thereby separating it from brackish feed for reproducing fresh water. A novel design of a cylindrical air gap membrane distillation module is presented. The module is fabricated in a way similar to a shell and tube heat exchanger. A PTFE hydrophobic membrane is used and is formed in a cylindrical shape. Design of experiments (DOE) is used to design the experiments statistically and to identify the significant operating parameters. Experiments were performed according to the Taguchi design approach using an L16 orthogonal array. Optimization of the whole process is performed by response surface methodology. It is shown that the feed temperature and feed flow rate have a positive effect, whereas the salinity has a negative impact on flux. The maximum value of flux achieved with this system is 3.6 kg/m2 hr. A high value of flux of 2.6 kg/m2 hr was achieved under optimum conditions at a temperature of 45 °C and a flow rate of 1.5 lpm with a salinity of 5 g/litre.

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