Effect of surfactant hydrophobicity and charge type on membrane distillation performance (original) (raw)
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Evolution of Membrane Surface Properties for Membrane Distillation: A Mini Review
Journal of Applied Membrane Science & Technology
To date, the membrane development for membrane distillation (MD) application is growing in line with the increasing volume of various types of wastewaters discharged into environment. MD is a liquid-vapor separation process and a hydrophobic membrane is used to retain the liquid. Theoretically, the hydrophobic membrane can achieve 100% rejection of non-volatile components that dissolved in feed liquids. As a result, MD has received significant attention in water recovery from saline water as well as wastewaters. Nevertheless, in addition to the scaling problem due to salts, the hydrophobicity property of membrane becomes a concern when dealing with challenging wastewaters which contain various types of low surface tension components such as oils, grease, alcohols, organics and surfactants. The membrane pore wetting due to salts deposition fouling and low surface tension components subsequently reduces the flux and even fails the liquid-vapor separation process. This article briefly ...
Desalination, 2003
Surfactants are present in almost all aqueous solutions-either as additives for different purposes, or because they occur naturally. Because of the common occurrence of surfactants in process water it is important to know how they behave in membrane processes. Ultrafiltration membranes allow almost complete passage of surfactant monomers, but reject micelles almost completely. Concentration polarisation during ultraflltration of surfactant solutions is therefore mainly influenced by the presence ofmicelles. Operating parameters, e.g. the tmnsmembrane pressure and the concentration of surfactant, as well as the pure water flux of the membrane, have a marked influence on the performance of hydrophilic membranes, as shown in this investigation. A distinct difference between the interaction of a non-ionic surfactant with hydrophilic and hydrophobic membranes was observed. The hydrophobic membrane showed a flux reduction already at concentrations below the critical micelle concentration (CMC), whereas no flux reduction was observed for a hydrophilic membrane with the same nominal molecular weight cutoff , below the CMC.
Towards practical implementations of membrane distillation
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Practical/industrial application MD energy source MD " extreme " application a b s t r a c t Membrane distillation, which combines thermal desalination and porous hydrophobic membrane as non-wetting contact media, is currently gaining increasing important in membrane processes. However, the vast researches and reported publications of membrane distillation (MD) are less followed by its practical/industrial applications. This paper review analyzes the reasons for MD has not widely being implemented in practical/industrial applications. In addition, the strategies towards practical application are presented. Thus, this review will complement previous review of MD papers.
Journal of Industrial and Engineering Chemistry, 2020
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Influence of module orientation and geometry in the membrane distillation of oily seawater
Desalination, 2017
To improve the mechanistic understanding for advancing the design and engineering of the membrane distillation (MD) modules, the objective of the current study was to investigate via both experiments and simulations the impact of (i) module orientation, (ii) module geometry, and (iii) an oily feed on the permeate flux and pore wetting propensity of direct contact membrane distillation (DCMD). Three module orientations and four feed channel geometries were investigated via experiments and simulations for oily feeds. Two key highlights emanated from this study. Firstly, module orientation mattered for DCMD, particularly in view of the formation of natural thermal convective currents and when the particle density of the particulate foulants varied. Particulate foulants with density much lesser and greater than water only deposited when the membrane was oriented respectively atop and beneath the feed. Secondly, the lack of consideration of convection currents, oil coalescence and the corresponding cake-enhanced temperature polarization in the simulations caused disagreement with the experimental results, which underscores the importance of these factors. This highlights that the optimization of MD modules particularly for treating oily feeds requires more mechanistic studies, especially in view of the thermal gradients, rather than relying on analogy with pressure-driven filtration processes.
Membrane distillation: theory and experiments
Journal of Membrane Science, 1996
A theoretical approach is presented that describes membrane distillation processes due to the simultaneous action (in a proactive or in a counteractive way) of temperature and concentration differences through porous hydrophobic membranes. The model developed emphasizes the importance of the boundary layers, shows the existence of a coupling term between the two thermodynamic forces acting on the system, and permits the definition and characterization of the so-called steady states. In order to check the model, two membranes have been studied in different experimental conditions. The influence of some relevant parameters, such as solution concentration, stirring rate, mean temperature and temperature difference has been considered and the theoretical predictions of the model have been applied to the obtained results. The accordance may be considered good.
Potential of membrane distillation - a comprehensive review
International Journal of Water, 2013
Membrane distillation (MD) is a recent and unique separation technology, in use in the process industry. The process of separation in MD involves the simultaneous heat and mass transfer through a hydrophobic semi permeable membrane, using thermal energy. Consequently a separation of the feed solution into two components-the permeate or product and the retentate or the return stream occurs. MD utilises low grade or alternative energy, e.g., solar energy, geothermal energy, etc., as a source and is the most cost effective separation technology. Hence the process has come to acquire the attention and interest of researchers, experimentalists and theoreticians all over the world. This article is a comprehensive review of the prominent research in the field of MD technology, including its basic principle, MD configurations, area of applications, membrane characteristics and modules, experimental studies involving the effect of main operating parameters, MD energy and economic, fouling and long-term performance.
Use of additives to enhance the selectivity of liquid surfactant membranes
Journal of Membrane Science, 1989
This study is aimed at attempting to improve both the selectivity and the permeation rates for the separation of 1-methylnaphthalene from dodecane using aqueous surfactant membranes. This enhancement is achieved by adding various water-soluble chemical compounds ("additives") to the water phase. Seven different additives were tried in this study and their efficacy was determined by carrying out mass transfer permeation experiments to determine both the rates of transfer and the selectivity of separation. In line with our previous work (Sharma et al. [ 51; Krishna et al. [ 6]), we have corrected the mass transfer coefficients for emulsion breakage, and found these coefficients, and the selectivity, to correlate well with the work of transfer of the additivecontaining surfactant system. The increase in selectivity in the presence of the additive has been shown to be due to the relative increase in the activity coefficient of 1-methylnaphthalene in the aqueous solution with respect to that of dodecane. The presence of the additive increases the selectivity by about one order of magnitude, and the present study should aid in the development of a viable liquid membrane separation process for the selective removal of aromatics from kerosene, a process which is required for the production of aviation turbine fuel from crudes having a high aromatic content in the lighter distillates.
Nature Environment and Pollution Technology
Hydrophobic membranes prepared using Poly (tetrafluoroethylene) (PTFE) along with Poly (1,4-phenylene ether ether-sulfone) and zinc oxide nanoparticle was used in membrane distillation. To examine seawater purification, prepared polymeric membranes were evaluated, tested, and used in a lab-scale direct contact membrane distillation arrangement. These membranes which are synthesized using the electrospinning method have good mechanical and thermal stability. To understand prepared membranes’ desalination performance, the physicochemical properties of the seawater were analyzed before and after membrane distillation. The salt rejection remained at 99% and the highest energy efficiency of the system observed is 67.3%.
Membrane distillation: A comprehensive review
Desalination
Membrane Distillation (MD) is a thermally-driven separation process, in which only vapour molecules transfer through a microporous hydrophobic membrane. The driving force in the MD process is the vapour pressure difference induced by the temperature difference across the hydrophobic membrane. This process has various applications, such as desalination, wastewater treatment and in the food industry. This review addresses membrane characteristics, membrane-related heat and mass transfer concepts, fouling and the effects of operating condition. State of the art research results in these different areas will be presented and discussed.