scholarly journals Factors Affecting Membrane Distillation Process for Seawater Desalination

2018 ◽  
Vol 22 (1) ◽  
Author(s):  
Ngo Thi Tra My ◽  
Vo Thi Yen Nhi ◽  
Bui Xuan Thanh
Keyword(s):  
Contact Angle ◽  
Membrane Separation ◽  
Membrane Distillation ◽  
Process Efficiency ◽  
Membrane Properties ◽  
Permeate Flux ◽  
Factors Affecting ◽  
Entry Pressure ◽  
Membrane Lifetime ◽  
Membrane Wetting

Membrane distillation (MD), a process based on the thermal principle, is a combination of distillation and membrane separation in the same unit. There are many factors that can affect the MD performance, but the membrane characteristics are the most important in this process. The changes in the membrane properties affect the process efficiency, the permeate flux as well as the membrane lifetime. Some of the membrane properties mentioned in this paper include liquid entry pressure (LEP), contact angle, pore size, porosity, thickness, thermal conductivity, support layer, tortuosity, etc. This review paper aims to evaluate the membrane properties in order to reduce membrane wetting and to improve desalination efficiency. From this review, it can be seen that the LEP and contact angle are the important factors which directly affect the hydrophobicity of the membrane. When LEP and the contact angle increase, the hydrophobicity of the membrane increases. Thus, the membrane is durable and the MD system works efficiently. The remaining factors indirectly affect the operation of the MD system through LEP and contact angle (hydrophobicity).

scholarly journals Theoretical and Experimental Desalination Using Ultrasound Assisted PVDF Membrane in Direct Contact Membrane Distillation

2019 ◽  
Vol 8 (6) ◽  
pp. 1229-1234
Keyword(s):  
Contact Angle ◽  
Pore Size ◽  
Transition Region ◽  
Direct Contact ◽  
Membrane Distillation ◽  
Membrane Properties ◽  
Permeate Flux ◽  
Pvdf Membrane ◽  
Direct Contact Membrane Distillation ◽  
Ultrasound Assisted

Desalination by the direct contact membrane distillation (DCMD) for prepared saline water and Ambazari lake water sample was investigated. The self-prepared ultrasound assisted polyvinylidene fluoride (PVDF) membrane by wet phase inversion method exhibited effects on membrane contact angle, pore size, and porosity and investigated performance of DCMD. Membrane properties are characterized and employed in theoretical model with assumptions for water vapor transport in the transition region. It is observed that similar pattern obtained for permeate flux from experimental results and simulated results for transition region. Effects of operating parameter on permeate flux also simulated and compared with experimental data. For this work mathematical models developed and simulated in Polymath. PVDF membrane exhibited its characteristics like contact angle, pore size and flux enhancement may be due to ultrasound assisted polymer solution preparation for membrane casting.

A review on membrane applications and transport mechanisms in vacuum membrane distillation

2017 ◽  
Vol 34 (1) ◽  
Author(s):  
Rakesh Baghel ◽  
Sushant Upadhyaya ◽  
Kailash Singh ◽  
Satyendra P. Chaurasia ◽  
Akhilendra B. Gupta ◽  
...  
Keyword(s):  
Membrane Fouling ◽  
Membrane Separation ◽  
Critical Evaluation ◽  
Experimental Studies ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
Separation Processes ◽  
Vacuum Membrane Distillation ◽  
Polarization Coefficient ◽  
The Impact

AbstractThe main aim of this article is to provide a state-of-the-art review of the experimental studies on vacuum membrane distillation (VMD) process. An introduction to the history of VMD is carried out along with the other membrane distillation configurations. Recent developments in process, characterization of membrane, module design, transport phenomena, and effect of operating parameters on permeate flux are discussed for VMD in detail. Several heat and mass transfer correlations obtained by various researchers for different VMD modules have been discussed. The impact of membrane fouling with its control in VMD is discussed in detail. In this paper, temperature polarization coefficient and concentration polarization coefficient are elaborated in detail. Integration of VMD with other membrane separation processes/industrial processes have been explained to improve the performance of the system and make it more energy efficient. A critical evaluation of the VMD literature is incorporated throughout this review.

scholarly journals Interplay of the Factors Affecting Water Flux and Salt Rejection in Membrane Distillation: A State-of-the-Art Critical Review

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2841
Author(s):  
Lin Chen ◽  
Pei Xu ◽  
Huiyao Wang
Keyword(s):  
Water Flux ◽  
Feed Solution ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Membrane Properties ◽  
Membrane Thickness ◽  
Membrane Pore ◽  
Factors Affecting ◽  
Term Operation ◽  
Salt Rejection

High water flux and elevated rejection of salts and contaminants are two primary goals for membrane distillation (MD). It is imperative to study the factors affecting water flux and solute transport in MD, the fundamental mechanisms, and practical applications to improve system performance. In this review, we analyzed in-depth the effects of membrane characteristics (e.g., membrane pore size and distribution, porosity, tortuosity, membrane thickness, hydrophobicity, and liquid entry pressure), feed solution composition (e.g., salts, non-volatile and volatile organics, surfactants such as non-ionic and ionic types, trace organic compounds, natural organic matter, and viscosity), and operating conditions (e.g., temperature, flow velocity, and membrane degradation during long-term operation). Intrinsic interactions between the feed solution and the membrane due to hydrophobic interaction and/or electro-interaction (electro-repulsion and adsorption on membrane surface) were also discussed. The interplay among the factors was developed to qualitatively predict water flux and salt rejection considering feed solution, membrane properties, and operating conditions. This review provides a structured understanding of the intrinsic mechanisms of the factors affecting mass transport, heat transfer, and salt rejection in MD and the intra-relationship between these factors from a systematic perspective.

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.

scholarly journals Membrane Distillation of Saline Water Contaminated with Oil and Surfactants

Membranes ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 988
Author(s):  
Wirginia Tomczak ◽  
Marek Gryta
Keyword(s):  
High Salinity ◽  
Sea Water ◽  
Saline Water ◽  
Sodium Dodecyl ◽  
Membrane Distillation ◽  
Process Efficiency ◽  
Feed Water ◽  
Permeate Flux ◽  
Low Concentration

Application of the membrane distillation (MD) process for the treatment of high-salinity solutions contaminated with oil and surfactants represents an interesting area of research. Therefore, the aim of this study is to investigate the effect of low-concentration surfactants in oil-contaminated high-salinity solutions on the MD process efficiency. For this purpose, hydrophobic capillary polypropylene (PP) membranes were tested during the long-term MD studies. Baltic Sea water and concentrated NaCl solutions were used as a feed. The feed water was contaminated with oil collected from bilge water and sodium dodecyl sulphate (SDS). It has been demonstrated that PP membranes were non-wetted during the separation of pure NaCl solutions over 960 h of the module exploitation. The presence of oil (100–150 mg/L) in concentrated NaCl solutions caused the adsorption of oil on the membranes surface and a decrease in the permeate flux of 30%. In turn, the presence of SDS (1.5–2.5 mg/L) in the oil-contaminated high-salinity solutions slightly accelerated the phenomenon of membrane wetting. The partial pores’ wetting accelerated the internal scaling and affected degradation of the membrane’s structure. Undoubtedly, the results obtained in the present study may have important implications for understanding the effect of low-concentration SDS on MD process efficiency.

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.      

Performance evaluation of ePTFE and PVDF flat-sheet module direct contact membrane distillation

2010 ◽  
Vol 62 (2) ◽  
pp. 347-352 ◽  
Author(s):  
Ching-Jung Chuang ◽  
Kuo-Lun Tung ◽  
Yang-Hsiang Fan ◽  
Chii-Dong Ho ◽  
James Huang
Keyword(s):  
Direct Contact ◽  
Polyvinylidene Fluoride ◽  
Membrane Distillation ◽  
Membrane Properties ◽  
Energy Integration ◽  
Permeate Flux ◽  
Increase Energy Efficiency ◽  
Module Design ◽  
Direct Contact Membrane Distillation ◽  
Flat Sheet

This paper reports experiments using a flat-sheet module with 0.18 ∼ 0.45 μm ePTFE (expanded polytetrafluoroethylene) and PVDF (polyvinylidene fluoride) membranes to show the effects of membrane properties, salt concentration and fluid hydrodynamics on the permeate flux and salt rejection of DCMD (direct contact membrane distillation). A theoretical prediction of the permeate flux was carried out, and was in close agreement with the experimental results. In addition, the energy integration of the process was also analyzed in order to evaluate module design to increase energy efficiency. According to the simulated results of the energy integration design, a combination of simultaneous cooling of the permeate stream and an additional heat exchanger to lower the temperature of the permeate stream not only enhances the MD flux, but also reduces energy consumption.

Investigation of Different Membrane Porosities on the Permeate Flux of Direct Contact Membrane Distillation

2021 ◽  
Vol 889 ◽  
pp. 85-90
Author(s):  
Asmaa Elrasheedy ◽  
Mohammed Rabie ◽  
Ahmed Hassan El-Shazly ◽  
Mohamed Bassyouni ◽  
Ahmed Abd El-Moneim ◽  
...  
Keyword(s):  
Contact Angle ◽  
Direct Contact ◽  
Solution Concentration ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
Hydrophobic Property ◽  
Water Contact ◽  
Direct Contact Membrane Distillation ◽  
Static Water ◽  
Membrane Porosity

In the present study the surface morphology of electrospun fibers at different polystyrene (PS) solution concentration was studied by SEM imaging to determine the best PS solution concentration yielding continuous uniform beadles fibers. Contact angle measurements of the optimum fabricatedPS-18 membrane confirmed the super hydrophobic property of the membrane that exhibited a static water contact angle of 145o. Numerical investigation of the performance of PS-18 membrane at different membrane thicknesses and porosities on direct contact membrane distillation showed that increasing the membrane porosity increases the permeate flux considerably.

scholarly journals Recent Developments in Nanomaterials-Modified Membranes for Improved Membrane Distillation Performance

Membranes ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 140 ◽  
Author(s):  
Saikat Sinha Ray ◽  
Harshdeep Singh Bakshi ◽  
Raghav Dangayach ◽  
Randeep Singh ◽  
Chinmoy Kanti Deb ◽  
...  
Keyword(s):  
Membrane Fouling ◽  
Membrane Separation ◽  
Interfacial Polymerization ◽  
Comprehensive Evaluation ◽  
Dip Coating ◽  
Membrane Distillation ◽  
Volatile Constituent ◽  
Volatile Components ◽  
Permeate Flux ◽  
Hydrophobic Membrane

Membrane distillation (MD) is a thermally induced membrane separation process that utilizes vapor pressure variance to permeate the more volatile constituent, typically water as vapor, across a hydrophobic membrane and rejects the less volatile components of the feed. Permeate flux decline, membrane fouling, and wetting are some serious challenges faced in MD operations. Thus, in recent years, various studies have been carried out on the modification of these MD membranes by incorporating nanomaterials to overcome these challenges and significantly improve the performance of these membranes. This review provides a comprehensive evaluation of the incorporation of new generation nanomaterials such as quantum dots, metalloids and metal oxide-based nanoparticles, metal organic frameworks (MOFs), and carbon-based nanomaterials in the MD membrane. The desired characteristics of the membrane for MD operations, such as a higher liquid entry pressure (LEPw), permeability, porosity, hydrophobicity, chemical stability, thermal conductivity, and mechanical strength, have been thoroughly discussed. Additionally, methodologies adopted for the incorporation of nanomaterials in these membranes, including surface grafting, plasma polymerization, interfacial polymerization, dip coating, and the efficacy of these modified membranes in various MD operations along with their applications are addressed. Further, the current challenges in modifying MD membranes using nanomaterials along with prominent future aspects have been systematically elaborated.

scholarly journals Phenol solutions treatment by using hydrophobized track-etched membranes

2020 ◽  
Vol 99 (3) ◽  
pp. 99-109
Author(s):  
A.B. Yeszhanov ◽  
◽  
S.S. Dosmagambetova ◽  
Keyword(s):  
Water Treatment ◽  
Water Flux ◽  
Membrane Distillation ◽  
Water Bodies ◽  
Permeate Flux ◽  
Sanitary Condition ◽  
Direct Contact Membrane Distillation ◽  
Membrane Characterization ◽  
Entry Pressure ◽  
Flux Measurements

Phenols are one of the most common surface water pollution. The discharge of phenolic waters into water bodies and streams sharply degrade their general sanitary condition, since these compounds have a toxic effect, and phenols can intensively absorb oxygen dissolved in water, which negatively affects the life of organisms in water bodies. Therefore, water treatment of phenols is an important environmental problem. In this study, the hydrophobic polyethylene terephthalate track-etched membranes (PET TeMs) were tested in water treatment from phenol by direct contact membrane distillation (DCMD). Hydrophobic PET TeMs were obtained by UV-graft polymerization of styrene, triethoxyvinylsilane with the addition of vinylimidazole (VIM), as well as by coating with fluorine-containing silanes. Scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and liquid entry pressure (LEP) analysis were used for membrane characterization. The contact angle after modification of PET TeMs was reached more than 130°. The efficiency of water purification from phenol was evaluated by water-flux measurements and fluorimetric method. The phenols solution was used at a concentration of 0.5, 1 and 2 g/l. The largest permeate flux of hydrophobized membranes was 1.1 kg/ m2•h.

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