The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Enrico Drioli - One of the best experts on this subject based on the ideXlab platform.
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ectfe Membrane fabrication via tips method using atbc diluent for Vacuum Membrane Distillation
Desalination, 2019Co-Authors: Yuchun Cai, Enrico Drioli, Naser Tavajohi Hassankiadeh, Yangming Cheng, Xiaozu Wang, Zhaohui Wang, Zhaoliang CuiAbstract:Abstract Poly (ethylene chlorotrifluoroethylene) (ECTFE) Membrane presents interesting properties for microfiltration (MF) and Membrane Distillation (MD). In this paper, ECTFE is prepared via thermally induced phase separation (TIPS) process using acetyl tributyl citrate (ATBC) as an environmentally friendly diluent. Phase diagram of the ECTFE/ATBC system is measured, and the effects of ECTFE concentration and quenching bath temperature on the Membrane structure, properties and performance are investigated, by characterizing with scanning electron microscope (SEM), pure water flux, contact angle, mechanical properties, mean pore size and porosity. The results show that the ECTFE Membranes prepared with ATBC as diluent possessed spherulite structure, high hydrophobicity and liquid entry pressure of water (LEPw), promising permeate flux, salt rejection and mechanical strength in Vacuum Membrane Distillation (VMD). The permeate flux reached to 22.3 L/(m2.h) with salt rejection rate of 99.9%. These results indicated that ECTFE Membranes prepared with green diluent ATBC is an interesting candidate for VMD operation.
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enhanced fouling and wetting resistance of composite hyflon ad poly vinylidene fluoride Membrane in Vacuum Membrane Distillation
Separation and Purification Technology, 2019Co-Authors: Yongxing Zhang, Enrico Drioli, Xiaozu Wang, Zhaohui Wang, Zhaoliang Cui, Jingyi Cao, Shouyong Zhou, Shuaifei ZhaoAbstract:Abstract Membrane fouling and pore wetting are the key problems affecting the separation performance of Membrane Distillation (MD). They can become more severe with increasing the operation time, which will have a negative impact on heat and mass transfers. In this paper, solutions containing CaCO3, humid acid (HA), and/or silica sols (SiO2) were used as the feed with different Hyflon AD/polyvinylidene fluoride (PVDF) composite Membranes for Vacuum Membrane Distillation (VMD). The evolutions of flux and salt rejection during the concentration process were examined, and the Membranes with different properties were compared. The results showed that the original Membrane was more prone to be fouled and wetted even at low concentration factors. In the single-component systems, CaCO3 impacts the Membrane performance most severely. With the hybrid component solutions, the flux declines for the composite Membranes were lower than that of the original Membrane. Compared with the single-component systems, the practical situation is more likely close to the hybrid-component system where fouling and wetting were easier to happen. Overall, the composite Membranes showed enhanced fouling and wetting resistance and maintained stable salt rejections. Particularly, the composite Membrane with smaller pore sizes (M-40L) performed best among all the Membranes, suggesting its high potential for practical VMD applications.
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tubular hydrophobic ceramic Membrane with asymmetric structure for water desalination via Vacuum Membrane Distillation process
Desalination, 2018Co-Authors: Xianfu Chen, Enrico Drioli, Zhaohui Wang, Kaiyun Fu, Feng Xiong, Dong DingAbstract:Abstract A porous ceramic Membrane without water wetting is essential for the application of water desalination in Membrane Distillation. In this study, we report a hydrophobic tubular asymmetric alumina Membrane that was modified by grafting hexadecyltrimethoxysilane (C16) molecules. The grafting efficiency and hydrophobicity of the grafted Membrane were characterized by its morphology, contact angle and FTIR spectrum, as well as the changes in terms of nitrogen permeance and pure water flux over various pressures. Four kinds of tubular asymmetric alumina Membranes were employed in the Vacuum Membrane Distillation (VMD) process. The effects of Membrane thickness and pore size on the water flux or salt retention were investigated. The mass transport resistance in substrate was non-negligible and sometimes could be the main contributor to the total mass transport resistance. The Membrane with a top layer thickness of 20 μm, pore size of 150 nm and support pore size of 3.2 μm was appropriate in the VMD process. After >1000 min desalination, the permeate flux and salt rejection were maintained as high as at the beginning, i.e., approximately 30 kg·m−2·h−1 and 99.9%, respectively.
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optimization of novel composite Membranes for water and mineral recovery by Vacuum Membrane Distillation
Desalination, 2017Co-Authors: Zhaoliang Cui, Enrico Drioli, Xiaozu Wang, Zhaohui Wang, Yongxing Zhang, Shuaifei ZhaoAbstract:Abstract In mining industries, the process combining ultrafiltration (UF) and reverse osmosis (RO) is often used for wastewater treatment, but RO brine discharge is a big issue. Membrane Distillation (MD) has been proposed to solve this problem by significantly increasing the water recovery ratio, and recovering minerals. However, Membranes with high hydrophobicity targeting for MD, particularly for Vacuum Membrane Distillation (VMD) are still scarce. Hyflon AD is a novel candidate for fabricating Membranes for MD. In this paper, the effects of Membrane fabrication parameters, such as coating time, heat treatment and pre-filling were investigated and optimized. Membrane morphology, mechanical properties and VMD performance of the composite Membranes were tested. The results showed that the hydrophobicity and elongation at break of the Membrane were significantly improved after coating. The coating polymer concentration, coating time, heat treatment temperature and heat treatment time for the Membrane coated by Hyflon AD40L and Hyflon AD40H, respectively were optimized. Monovalent alcohols can be excellent pre-filling agents to improve Membrane performance. Separation performance of the Membrane coated by Hyflon AD40H was better than that of the one coated by Hyflon AD40L.
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enhancing wetting resistance of poly vinylidene fluoride Membranes for Vacuum Membrane Distillation
Desalination, 2017Co-Authors: Yongxing Zhang, Enrico Drioli, Xiaozu Wang, Zhaohui Wang, Zhaoliang Cui, Shuaifei ZhaoAbstract:Abstract Composite Membranes were fabricated by coating three types of highly hydrophobic perfluorinated copolymers (commercial name: Hyflon AD) on poly(vinylidene fluoride) hollow fibers. The Membrane properties, including morphologies, pore sizes, porosities, liquid entry pressures (LEPs), mechanical strength, and separation performance (flux, rejection and wettability) in Vacuum Membrane Distillation (VMD) were systematically characterized and investigated. The properties of the fabricated Membranes, including pore sizes, pore size distributions, porosities, and LEPs were significantly affected by the viscosity of the coating polymer solution. Coating solutions with lower viscosities caused smaller pore sizes, narrower pore size distributions, lower porosities, higher LEPs and less flux decline in VMD. Particularly, LEP of the Membrane coated with a lower viscosity solution (0.46 MPa) was two times higher than that of the uncoated Membrane (0.23 MPa). As a result, the anti-wetting property of the composite Membrane after coating was significantly enhanced compared with that of the original Membrane. The coated composite hollow fiber Membranes also showed improved hydrophobicity, mechanical strength and separation performance (water flux and salt rejection). The water contact angle of the Membrane increased from 94 to 145° after coating with a lower viscosity solution.
Takeshi Matsuura - One of the best experts on this subject based on the ideXlab platform.
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modeling of pore wetting in Vacuum Membrane Distillation
Journal of Membrane Science, 2019Co-Authors: Hooman Chamani, Takeshi Matsuura, Dipak Rana, Christopher Q LanAbstract:Abstract In this work simulation results for the pore wetting of Vacuum Membrane Distillation (VMD) are reported, considering heat and mass balance at liquid/vapor interface when steady state is achieved. Two cases were studied. In case 1, the system is in isothermal condition. In case 2, heat enters only from the pore inlet and is removed at the liquid/vapor interface as liquid vaporizes. The simulation has shown that the liquid/vapor boundary may remain inside the pore at the steady state condition, which means the partial pore wetting is possible. The significant temperature drop from the pore entrance to the liquid/vapor interface has also been predicted. It was found from case 2 simulation that VMD is possible in a wider range of pore radius, r, than the Laplace equation predicts. As well, the possibility of VMD for the contact angle (θ) below 90° was justified.
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the heat and mass transfer of Vacuum Membrane Distillation effect of active layer morphology with and without support material
Separation and Purification Technology, 2016Co-Authors: Yifan Yang, Dipak Rana, Takeshi MatsuuraAbstract:Abstract The aim of this research was the analysis of heat and mass transfer in Vacuum Membrane Distillation (VMD), specifically for a dead-end feed set-up. The influence of support material on the supported Membranes VMD performance was identified. A mathematical model was proposed to evaluate the Membrane/feed interface temperature, Membrane tortuosity, Membrane mass transfer coefficient, and temperature polarization coefficient (TPC). The model was solved by an excel solver based on experimental results of feed temperature, system pressure and the evaporative fluxes. The SEM images showed that the thickness of unsupported Membrane was reduced by 42% after the VMD test. Pore shrinkage and tortuosity increase were also expected during this pore collapsing process. On the other hand, the cross-sectional views of the supported Membranes did not show significant changes. These results show that the support material can help prevent the Membrane pore channel structure from collapsing during the VMD experiment. TPC is close to unity at low feed temperatures. However, it decreases with an increase in evaporation flux as the feed temperature increases, or when a high flux supported Membrane is applied.
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study on structure and Vacuum Membrane Distillation performance of pvdf Membranes ii influence of molecular weight
Chemical Engineering Journal, 2015Co-Authors: Zuolong Che, Takeshi Matsuura, Dipak Rana, Derek MengAbstract:Abstract Membranes were prepared from three poly(vinylidene fluoride) (PVDF) of different molecular weights by the phase inversion process. The Membranes were characterized by scanning electron microscopy, gas permeation tests, contact angle (CA) and liquid entry pressure of water (LEPw) measurements, and further subjected to the test of flux for Vacuum Membrane Distillation (VMD) in a scenario that is applicable for cooling processes. The results showed that the increase in PVDF molecular weight increased the viscosity and thermodynamic instability of the casting solution significantly. Regarding characterization and performance testing, the Membrane prepared from the intermediate molecular weight of Kynar® MG 15 polymer showed the highest VMD flux (325 g/m 2 h) at the feed temperature of 27 °C and the lowest LEPw (622 kPa) due to the largest pore size (49.8 nm) observed among all the tested Membranes. The highest flux of this particular Membrane seems also due to the thinnest finger-like and sponge-like layer.
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Effects of superhydrophobic SiO2 nanoparticles on the performance of PVDF flat sheet Membranes for Vacuum Membrane Distillation
Desalination, 2015Co-Authors: Johnson E. Efome, Takeshi Matsuura, Dipak Rana, Mohammadali Baghbanzadeh, Christopher Q LanAbstract:Abstract Polyvinylidene fluoride (PVDF)/SiO2 flat sheet composite Membranes were prepared for Vacuum Membrane Distillation (VMD) by the phase inversion immersion precipitation process. The effect of blending superhydrophobic SiO2 nanoparticles into the PVDF dope solution was studied. The concentration of the nanoparticles in the dope solution was varied at different wt.% (1, 2, 4, 6, 7, 8 and 10 wt.%). The prepared Membranes were characterized by scanning electron microscopy, water contact angle, porosity, liquid entry pressure of water, Fourier transformed infrared spectroscopy, and VMD at feed temperature of 27 °C. The nanoparticles enhanced the Membrane performance through a reduction in the sponge-like layer thickness and an increase in surface pore size, leading to increased vapour flux with a maximum at 7 wt.%. The salt rejection was greater than 99.98% when a 35 g/L NaCl solution was used as feed. At this concentration, the smallest thickness of the sponge-like layer and largest macro-voids were also achieved. Beyond 7 wt.%, the sponge-like layer became predominant and the flux was reduced. With a vapour flux increase of up to 4 times (from 0.7 to 2.9 kg/m2 h) when compared to the neat Membrane, this nanocomposite Membrane could be of great potential in the desalination process through VMD.
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Study on the structure and Vacuum Membrane Distillation performance of PVDF composite Membranes: I. Influence of blending
Separation and Purification Technology, 2014Co-Authors: Zoulong Chen, Takeshi Matsuura, Dipak Rana, Yifan Yang, Christopher Q LanAbstract:Abstract In this study Membranes were fabricated from the blend of high (H) and low (L) molecular weights poly(vinylidene fluoride) by the phase inversion process. The Membranes so fabricated were characterized by scanning electron microscopy, gas permeation tests, contact angle (CA) and liquid entry pressure of water (LEPw) measurement, and further subjected to Vacuum Membrane Distillation (VMD) in a scenario that was applicable for cooling processes, where the feed water temperature was maintained at 27 °C. It was found that the H:L mixing ratio did not affect the Membrane surface hydrophobicity (as reflected by the CA) significantly. The water vapor flux of VMD was found to be the highest at the intermediate range of H:L ratio, i.e., 4:6, at which the thickness of the sponge-like layer showed a minimum, the pore size showed a maximum, the finger-like macro-voids formed a more orderly single-layer structure, and the LEPw showed a minimum.
Shuaifei Zhao - One of the best experts on this subject based on the ideXlab platform.
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enhanced fouling and wetting resistance of composite hyflon ad poly vinylidene fluoride Membrane in Vacuum Membrane Distillation
Separation and Purification Technology, 2019Co-Authors: Yongxing Zhang, Enrico Drioli, Xiaozu Wang, Zhaohui Wang, Zhaoliang Cui, Jingyi Cao, Shouyong Zhou, Shuaifei ZhaoAbstract:Abstract Membrane fouling and pore wetting are the key problems affecting the separation performance of Membrane Distillation (MD). They can become more severe with increasing the operation time, which will have a negative impact on heat and mass transfers. In this paper, solutions containing CaCO3, humid acid (HA), and/or silica sols (SiO2) were used as the feed with different Hyflon AD/polyvinylidene fluoride (PVDF) composite Membranes for Vacuum Membrane Distillation (VMD). The evolutions of flux and salt rejection during the concentration process were examined, and the Membranes with different properties were compared. The results showed that the original Membrane was more prone to be fouled and wetted even at low concentration factors. In the single-component systems, CaCO3 impacts the Membrane performance most severely. With the hybrid component solutions, the flux declines for the composite Membranes were lower than that of the original Membrane. Compared with the single-component systems, the practical situation is more likely close to the hybrid-component system where fouling and wetting were easier to happen. Overall, the composite Membranes showed enhanced fouling and wetting resistance and maintained stable salt rejections. Particularly, the composite Membrane with smaller pore sizes (M-40L) performed best among all the Membranes, suggesting its high potential for practical VMD applications.
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relating water vapor transfer to ammonia recovery from biogas slurry by Vacuum Membrane Distillation
Separation and Purification Technology, 2018Co-Authors: Xing Yang, Mikel Duke, Yanli Zhang, Shuaifei ZhaoAbstract:Abstract As the byproduct of biogas production, biogas slurry with high content of ammonia nitrogen may cause serious environmental problems (e.g. eutrophication). Ammonia recovery from biogas slurry is of great importance in minimizing the environmental impacts and maximizing the benefits. This study explores the role of water vapor transfer in ammonia recovery from biogas slurry by Vacuum Membrane Distillation. The overall mass transfer coefficients, ammonia separation factors and ammonia fluxes are used to evaluate ammonia separation performance. Effects of various operating parameters including the feed temperature, flow rate, initial pH of biogas slurry and Vacuum pressure on ammonia separation performance are investigated and discussed. Ammonia separation performance is dominated by the initial pH of biogas slurry. Optimizing operational parameters can effectively increase the overall mass transfer coefficient, but does not necessarily improve the ammonia separation factor. Water flux has an important impact on the overall ammonia transfer coefficient. An interesting S curve logistic model can well fit the relationship between the water flux and the overall ammonia transfer coefficient, suggesting that there is an optimal water flux. A relatively high concentration aqueous ammonia (up to 1.0 mol-N/L, much higher than the value in feed biogas slurry
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optimization of novel composite Membranes for water and mineral recovery by Vacuum Membrane Distillation
Desalination, 2017Co-Authors: Zhaoliang Cui, Enrico Drioli, Xiaozu Wang, Zhaohui Wang, Yongxing Zhang, Shuaifei ZhaoAbstract:Abstract In mining industries, the process combining ultrafiltration (UF) and reverse osmosis (RO) is often used for wastewater treatment, but RO brine discharge is a big issue. Membrane Distillation (MD) has been proposed to solve this problem by significantly increasing the water recovery ratio, and recovering minerals. However, Membranes with high hydrophobicity targeting for MD, particularly for Vacuum Membrane Distillation (VMD) are still scarce. Hyflon AD is a novel candidate for fabricating Membranes for MD. In this paper, the effects of Membrane fabrication parameters, such as coating time, heat treatment and pre-filling were investigated and optimized. Membrane morphology, mechanical properties and VMD performance of the composite Membranes were tested. The results showed that the hydrophobicity and elongation at break of the Membrane were significantly improved after coating. The coating polymer concentration, coating time, heat treatment temperature and heat treatment time for the Membrane coated by Hyflon AD40L and Hyflon AD40H, respectively were optimized. Monovalent alcohols can be excellent pre-filling agents to improve Membrane performance. Separation performance of the Membrane coated by Hyflon AD40H was better than that of the one coated by Hyflon AD40L.
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enhancing wetting resistance of poly vinylidene fluoride Membranes for Vacuum Membrane Distillation
Desalination, 2017Co-Authors: Yongxing Zhang, Enrico Drioli, Xiaozu Wang, Zhaohui Wang, Zhaoliang Cui, Shuaifei ZhaoAbstract:Abstract Composite Membranes were fabricated by coating three types of highly hydrophobic perfluorinated copolymers (commercial name: Hyflon AD) on poly(vinylidene fluoride) hollow fibers. The Membrane properties, including morphologies, pore sizes, porosities, liquid entry pressures (LEPs), mechanical strength, and separation performance (flux, rejection and wettability) in Vacuum Membrane Distillation (VMD) were systematically characterized and investigated. The properties of the fabricated Membranes, including pore sizes, pore size distributions, porosities, and LEPs were significantly affected by the viscosity of the coating polymer solution. Coating solutions with lower viscosities caused smaller pore sizes, narrower pore size distributions, lower porosities, higher LEPs and less flux decline in VMD. Particularly, LEP of the Membrane coated with a lower viscosity solution (0.46 MPa) was two times higher than that of the uncoated Membrane (0.23 MPa). As a result, the anti-wetting property of the composite Membrane after coating was significantly enhanced compared with that of the original Membrane. The coated composite hollow fiber Membranes also showed improved hydrophobicity, mechanical strength and separation performance (water flux and salt rejection). The water contact angle of the Membrane increased from 94 to 145° after coating with a lower viscosity solution.
Guicheng Liu - One of the best experts on this subject based on the ideXlab platform.
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superhydrophobic alumina hollow ceramic Membrane modified by tio2 nanorod array for Vacuum Membrane Distillation
Journal of The Taiwan Institute of Chemical Engineers, 2020Co-Authors: Shuangshuang Dong, Manxiang Wang, Yanbin Yun, Woochul Yang, Guicheng LiuAbstract:Abstract Problematic fouling along with wetting of Membrane represent the main barriers for large-scale application of this technology. To solve the above problems and reinforce the anti-pollution and anti-wetting features of the distilling Membrane, a brand-new TiO2 nanorods and 1H,1H,2H,2H-perfluorodecylsilane-triethoxy (PDTS) modified alumina hollow ceramic Membrane with superhydrophobic surface and self-cleaning property was prepared for utilization in the Vacuum Membrane Distillation. To synthesize the novel Membrane, a seed layer was supported on the hollow ceramic Membrane by the immersion-calcination method. Then, the TiO2 nanorods were grown on the Membrane by hydrothermal method and annealed to strengthen the crystal structure. Finally, the nanorod-grown Membrane was immersed in an alcohol solution of PDTS for hydrophobic treatment. The resulted modified Membrane was applied to the Distillation process to treat 100 g L−1 of concentrated brine for 3 h. It was revealed that the modified Membrane possessed with a lower ionic conductivity under 20 µs.cm−1 of the permeated liquid and desirable surface superhydrophobicity at appropriate water contact angle of 152°, thus showing great promise for use in the Membrane Distillation process.
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zno nanorod array modified pvdf Membrane with superhydrophobic surface for Vacuum Membrane Distillation application
ACS Applied Materials & Interfaces, 2018Co-Authors: Manxiang Wang, Guicheng Liu, Sanghyup Lee, Lei Wang, Jianzhong Zheng, Tao Wang, Joong Kee LeeAbstract:The Vacuum Membrane Distillation (VMD) is a promising technology for lots of applications. To solve the Membrane fouling and wetting problems, in this paper, a novel ZnO nanorods 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDTS) modified poly(vinylidene fluoride) (PVDF) Membrane with a micro/nanoscale hierarchical structure and a superhydrophobic surface has been prepared and applied to the VMD process for distilling highly salty water, for the first time. Among these, a pyrolysis–adhesion method is created to obtain the ZnO seeds and fasten them on the PVDF substrate firmly. The novel modified Membrane shows a stable superhydrophobic surface with a water contact angle of 152°, easy cleaning property, excellent thermal and mechanical stability, because of the Cassie’s state caused by pocketing much air in the hydrophobized ZnO nanorods, the low surface energy of PDTS coating, and the strong adhesion between ZnO nanorods and PVDF Membrane, which has built an ideal structure for VMD application. After 8 h VM...
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ZnO Nanorod Array Modified PVDF Membrane with Superhydrophobic Surface for Vacuum Membrane Distillation Application
2018Co-Authors: Manxiang Wang, Guicheng Liu, Sanghyup Lee, Lei Wang, Jianzhong Zheng, Tao Wang, Yanbin Yun, Joong Kee LeeAbstract:The Vacuum Membrane Distillation (VMD) is a promising technology for lots of applications. To solve the Membrane fouling and wetting problems, in this paper, a novel ZnO nanorods 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDTS) modified poly(vinylidene fluoride) (PVDF) Membrane with a micro/nanoscale hierarchical structure and a superhydrophobic surface has been prepared and applied to the VMD process for distilling highly salty water, for the first time. Among these, a pyrolysis–adhesion method is created to obtain the ZnO seeds and fasten them on the PVDF substrate firmly. The novel modified Membrane shows a stable superhydrophobic surface with a water contact angle of 152°, easy cleaning property, excellent thermal and mechanical stability, because of the Cassie’s state caused by pocketing much air in the hydrophobized ZnO nanorods, the low surface energy of PDTS coating, and the strong adhesion between ZnO nanorods and PVDF Membrane, which has built an ideal structure for VMD application. After 8 h VMD of 200 g L–1 NaCl solution, compared to the virgin PVDF Membrane, the novel Membrane shows a similar permeate flux but a much higher quality permeated liquid because of its unique antifouling and antiwetting caused by the several microns gap between the feed and the Membrane. Due to its easy cleaning property, the novel Membrane also exhibits an excellent reusability
Corinne Cabassud - One of the best experts on this subject based on the ideXlab platform.
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Direct As(III) removal from brackish groundwater by Vacuum Membrane Distillation: Effect of organic matter and salts on Membrane fouling
Separation and Purification Technology, 2016Co-Authors: Thanh Duong Dao, Stéphanie Laborie, Corinne CabassudAbstract:Arsenic contamination of shallow ground water is being one of the biggest health threats in the world, particularly in Asia. In this work, Vacuum Membrane Distillation (VMD) was proposed as an advanced solution for arsenic removal. The case study concerned arsenic contamination in Vietnam, where drinking water resources present not only high arsenic concentration (1–3050 ppb) but also high salinity (5–15 g/L). For that reason, synthetic brackish solutions containing NaCl (10 g/L) and As(III) (at different concentrations – between 300 and 2000 ppb) were used as feed solution in this study. As a result, VMD was capable to satisfy As(III) rejection to meet the required standard in the permeate (MCL = 10 ppb). Salt rejection was also very high (>99.5%). The As(III) rejection rate was always stable at high level (>98.5%), irrespective of high feed As(III) concentrations (up to 2000 ppb). With VMD, a pre-oxidation step was not necessary to convert As(III) into As(V), as it is the case for other conventional treatment processes. Furthermore, no effect of organic matter (humic acid) and calcium on Membrane scaling and fouling phenomena was observed at the given concentration in this study.
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a new method for permeability measurement of hydrophobic Membranes in Vacuum Membrane Distillation process
Water Research, 2013Co-Authors: Than Duong Dao, Jeanpierre Mericq, Corinne Cabassud, Stéphanie LaborieAbstract:Abstract In this paper, a new method for permeability measurement of hydrophobic Membranes used in Vacuum Membrane Distillation, instead of common measurement methods, was proposed. As VMD is a pressure and temperature driven process, the idea of this work is to propose a new water vapour permeability measurement method based on variation of feed temperature at a fixed Vacuum pressure. This new method showed a greater stability and simplicity than the existing pressure variation method by not only allowing a wide range of feed temperature (25 °C ÷ 60 °C) to be scanned continuously, but also avoiding fluctuations of the system as observed in the pressure variation test. Permeabilities of two different kinds of hydrophobic Membranes were measured by this new method and also by the existing pressure variation test. A comparison between these two methods was also presented to assess the feasibility and applicability of this new method.
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evaluation of systems coupling Vacuum Membrane Distillation and solar energy for seawater desalination
Chemical Engineering Journal, 2011Co-Authors: Jeanpierre Mericq, Stéphanie Laborie, Corinne CabassudAbstract:Abstract Vacuum Membrane Distillation (VMD) is a hybrid Membrane-evaporative process which has been shown to be of interest for seawater desalination. The main drawback of this process is the relatively high energy requirement linked to the need to heat the feed water. A way to solve this problem could be the use of a renewable source such as solar energy to provide the heat energy required. Two solutions of solar energy use are investigated in this paper: salinity gradient solar ponds (SGSP) and solar collectors (SC). For each solution, two configurations were studied. The first was based on pre-heating the feed seawater before the Membrane process while the second used a Membrane module directly coupled with solar energy, i.e. a Membrane submerged in an SGSP or an SC integrated at the surface of the Membrane module. VMD process simulations were carried out for the four different configurations with VMD modelling software previously developed and adapted to the different combinations. Simulation results showed that immersing the Membrane module directly in an SGSP could induce marked concentration and temperature polarisation phenomena that reduced fluxes. Turbulence had to be created in the feed seawater to reduce polarisations and this option was difficult to combine with an SGSP. The most interesting solution seemed to be the use of SC. High fluxes of 140 L h −1 m −2 could be reached (for a Vacuum pressure of 500 Pa and a Membrane with a Knudsen permeability of 1.85 × 10 −5 s mol 1/2 m −1 kg −1/2 ).
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Vacuum Membrane Distillation of seawater reverse osmosis brines
Water Research, 2010Co-Authors: Jeanpierre Mericq, Stéphanie Laborie, Corinne CabassudAbstract:Abstract Seawater desalination by Reverse Osmosis (RO) is an interesting solution for drinking water production. However, because of limitation by the osmotic pressure, a high recovery factor is not attainable. Consequently, large volumes of brines are discharged into the sea and the flow rate produced (permeate) is limited. In this paper, Vacuum Membrane Distillation (VMD) is considered as a complementary process to RO to further concentrate RO brines and increase the global recovery of the process. VMD is an evaporative technology that uses a Membrane to support the liquid–vapour interface and enhance the contact area between liquid and vapour in comparison with conventional Distillation. This study focuses on VMD for the treatment of RO brines. Simulations were performed to optimise the operating conditions and were completed by bench-scale experiments using actual RO brines and synthetic solutions up to a salt concentration of 300 g L−1. Operating conditions such as a highly permeable Membrane, high feed temperature, low permeate pressure and a turbulent fluid regime allowed high permeate fluxes to be obtained even for a very high salt concentration (300 g L−1). For the Membrane studied, temperature and concentration polarisation were shown to have little effect on permeate flux. After 6 to 8 h, no organic fouling or biofouling was observed for RO brines. At high salt concentrations, scaling occurred (mainly due to calcium precipitation) but had only a limited impact on the permeate flux (24% decrease for a permeate specific volume of 43L m−2 for the highest concentration of salt). Calcium carbonate and calcium sulphate precipitated first due to their low solubility and formed mixed crystal deposits on the Membrane surface. These phenomena only occurred on the Membrane surface and did not totally cover the pores. The crystals were easily removed simply by washing the Membrane with water. A global recovery factor of 89% can be obtained by coupling RO and VMD.
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Vacuum Membrane Distillation for an integrated seawater desalination process
Desalination and Water Treatment, 2009Co-Authors: Jeanpierre Mericq, Stéphanie Laborie, Corinne CabassudAbstract:Seawater desalination by reverse osmosis (RO) is widely used for drinking water production. In order to reduce the volume of brines and to increase recovery, a new approach is proposed in the frame of the European MEDINA project. It lies on a combination of RO and Vacuum Membrane Distillation (VMD) in order to over concentrated RO retentates and to reduce their volume. Indeed, VMD can be used for concentrated salty solutions, because concentration polarization and temperature polarization might be non limiting even for quite high salt concentrations. The objective of this paper is to provide some first trends on the feasibility of using VMD for enhancing the global process recovery. The approach is firstly based on simulations for highly concentrated solutions using a VMD modeling based on Knudsen diffusion through the Membrane which was improved to take into account highly concentrated waters. The model was validated by experimental results obtained with different salty solutions and with both flat-sheet...
