The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Mohamed Khayet - One of the best experts on this subject based on the ideXlab platform.
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application of a porous composite hydrophobic Hydrophilic Membrane in desalination by air gap and liquid gap Membrane distillation a comparative study
Separation and Purification Technology, 2014Co-Authors: M. Essalhi, Mohamed KhayetAbstract:Abstract A first attempt was carried out comparing the two Membrane distillation (MD) configurations, liquid gap (LGMD) and air gap (AGMD), using a porous composite hydrophobic/Hydrophilic Membrane, the same system and the same MD operating parameters. The surface modified Membrane was prepared by the phase inversion technique in a single casting step using a fluorinated surface modifying macromolecule (SMM). Different Membrane characterization techniques were applied. MD experiments were performed at different feed temperatures and sodium chloride aqueous solutions. The permeate fluxes were found to be slightly higher (2.2–6.5%) for LGMD compared to that of AGMD although the resistance to mass transfer in LGMD is higher due to the presence of the liquid permeate layer between the Membrane and the cooling solid surface. This observed enhancement is attributed partly to the small established distance between the liquid/vapor interfaces at both side of the hydrophobic thin top-layer of the Membrane in LGMD configuration, and the higher thermal conductivity of water, which is an order of magnitude higher than that of air, resulting in higher heat transfer coefficient of the permeate in LGMD. The salt rejection factors were found to be almost similar for both MD variants and higher than 99.61%. Compared to AGMD, the thermal efficiency is higher for LGMD, whereas the specific internal heat loss is lower. A linear increase of the thermal efficiency with the feed inlet temperature was observed for both MD configurations. The global heat transfer coefficient and the heat transfer of the permeate Membrane side were also found to be greater for LGMD. The temperature polarization effect was found to be slightly higher for AGMD, whereas the concentration polarization effect was slightly higher for LGMD due to its higher permeate flux. In general, the LGMD proved to be more attractive than AGMD for desalination when using bi-layered hydrophobic/Hydrophilic Membranes.
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Application of a porous composite hydrophobic/Hydrophilic Membrane in desalination by air gap and liquid gap Membrane distillation: A comparative study
Separation and Purification Technology, 2014Co-Authors: M. Essalhi, Mohamed KhayetAbstract:Abstract A first attempt was carried out comparing the two Membrane distillation (MD) configurations, liquid gap (LGMD) and air gap (AGMD), using a porous composite hydrophobic/Hydrophilic Membrane, the same system and the same MD operating parameters. The surface modified Membrane was prepared by the phase inversion technique in a single casting step using a fluorinated surface modifying macromolecule (SMM). Different Membrane characterization techniques were applied. MD experiments were performed at different feed temperatures and sodium chloride aqueous solutions. The permeate fluxes were found to be slightly higher (2.2–6.5%) for LGMD compared to that of AGMD although the resistance to mass transfer in LGMD is higher due to the presence of the liquid permeate layer between the Membrane and the cooling solid surface. This observed enhancement is attributed partly to the small established distance between the liquid/vapor interfaces at both side of the hydrophobic thin top-layer of the Membrane in LGMD configuration, and the higher thermal conductivity of water, which is an order of magnitude higher than that of air, resulting in higher heat transfer coefficient of the permeate in LGMD. The salt rejection factors were found to be almost similar for both MD variants and higher than 99.61%. Compared to AGMD, the thermal efficiency is higher for LGMD, whereas the specific internal heat loss is lower. A linear increase of the thermal efficiency with the feed inlet temperature was observed for both MD configurations. The global heat transfer coefficient and the heat transfer of the permeate Membrane side were also found to be greater for LGMD. The temperature polarization effect was found to be slightly higher for AGMD, whereas the concentration polarization effect was slightly higher for LGMD due to its higher permeate flux. In general, the LGMD proved to be more attractive than AGMD for desalination when using bi-layered hydrophobic/Hydrophilic Membranes.
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surface segregation of fluorinated modifying macromolecule for hydrophobic Hydrophilic Membrane preparation and application in air gap and direct contact Membrane distillation
Journal of Membrane Science, 2012Co-Authors: M. Essalhi, Mohamed KhayetAbstract:A fluorinated surface modifying macromolecule (SMM) was synthesized and blended into the casting solution of polyetherimide used as host polymer. A composite porous hydrophobic/Hydrophilic Membrane was prepared by the phase inversion technique in a single casting step. The Membrane was characterized by different techniques. During Membrane formation, SMM migrates to the top Membrane surface increasing its hydrophobicity and decreasing its pore size, nodule size and roughness parameters. The thickness of the porous hydrophobic top layer was found to be around 4 mu m. The Membrane was used for desalination by air gap Membrane distillation and direct contact Membrane distillation. The experiments were performed for different sodium chloride aqueous solutions and various operating conditions. The water production rate was found to be high for direct contact Membrane distillation because of the low resistance to mass transport achieved by the diminution of the water vapour transport path length through the hydrophobic thin top-layer of the Membrane.
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Surface segregation of fluorinated modifying macromolecule for hydrophobic/Hydrophilic Membrane preparation and application in air gap and direct contact Membrane distillation
Journal of Membrane Science, 2012Co-Authors: M. Essalhi, Mohamed KhayetAbstract:A fluorinated surface modifying macromolecule (SMM) was synthesized and blended into the casting solution of polyetherimide used as host polymer. A composite porous hydrophobic/Hydrophilic Membrane was prepared by the phase inversion technique in a single casting step. The Membrane was characterized by different techniques. During Membrane formation, SMM migrates to the top Membrane surface increasing its hydrophobicity and decreasing its pore size, nodule size and roughness parameters. The thickness of the porous hydrophobic top layer was found to be around 4 mu m. The Membrane was used for desalination by air gap Membrane distillation and direct contact Membrane distillation. The experiments were performed for different sodium chloride aqueous solutions and various operating conditions. The water production rate was found to be high for direct contact Membrane distillation because of the low resistance to mass transport achieved by the diminution of the water vapour transport path length through the hydrophobic thin top-layer of the Membrane.
Pascal E. Saikaly - One of the best experts on this subject based on the ideXlab platform.
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Temporal changes in extracellular polymeric substances on hydrophobic and Hydrophilic Membrane surfaces in a submerged Membrane bioreactor
Water research, 2016Co-Authors: Gerald Matar, Graciela Gonzalez-gil, Husnul Maab, Suzana Pereira Nunes, Pierre Le-clech, Johannes S. Vrouwenvelder, Pascal E. SaikalyAbstract:Membrane surface Hydrophilic modification has always been considered to mitigating biofouling in Membrane bioreactors (MBRs). Four hollow-fiber ultrafiltration Membranes (pore sizes ∼0.1 μm) differing only in hydrophobic or Hydrophilic surface characteristics were operated at a permeate flux of 10 L/m(2) h in the same lab-scale MBR fed with synthetic wastewater. In addition, identical Membrane modules without permeate production (0 L/m(2) h) were operated in the same lab-scale MBR. Membrane modules were autopsied after 1, 10, 20 and 30 days of MBR operation, and total extracellular polymeric substances (EPS) accumulated on the Membranes were extracted and characterized in detail using several analytical tools, including conventional colorimetric tests (Lowry and Dubois), liquid chromatography with organic carbon detection (LC-OCD), fluorescence excitation - emission matrices (FEEM), fourier transform infrared (FTIR) and confocal laser scanning microscope (CLSM). The transMembrane pressure (TMP) quickly stabilized with higher values for the hydrophobic Membranes than Hydrophilic ones. The sulfonated polysulfone (SPSU) Membrane had the highest negatively charged Membrane surface, accumulated the least amount of foulants and displayed the lowest TMP. The same type of organic foulants developed with time on the four Membranes and the composition of biopolymers shifted from protein dominance at early stages of filtration (day 1) towards polysaccharides dominance during later stages of MBR filtration. Nonmetric multidimensional scaling of LC-OCD data showed that biofilm samples clustered according to the sampling event (time) regardless of the Membrane surface chemistry (hydrophobic or Hydrophilic) or operating mode (with or without permeate flux). These results suggest that EPS composition may not be the dominant parameter for evaluating Membrane performance and possibly other parameters such as biofilm thickness, porosity, compactness and structure should be considered in future studies for evaluating the development and impact of biofouling on Membrane performance.
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Evolution and accumulation of organic foulants on hydrophobic and Hydrophilic Membrane surfaces in a submerged Membrane bioreactor
2015Co-Authors: Gerald Matar, Graciela Gonzalez-gil, Husnul Maab, Suzana Pereira Nunes, Johannes S. Vrouwenvelder, Pascal E. SaikalyAbstract:Membrane surface modification is attracting more attention to mitigate biofouling in Membrane bioreactors (MBRs). Five Membranes differing in chemistry and hydrophobic/Hydrophilic potential were run in parallel in a lab-scale MBR under the same conditions. Membranes were sampled after 1, 10, 20 and 30 days of MBR operation with synthetic wastewater. Subsequently, accumulated organic foulants were characterised using several chemical analytical tools. Results showed similar development of organic foulants with time, illustrating that Membrane surface chemistry did not affect the selection of specific organic foulants. Multivariate analysis showed that biofilm samples clustered according to the day of sampling. The composition of organic foulants shifted from protein-like substances towards humics and polysaccharides-like substances. We propose that to control biofouling in MBRs, one should focus less on the Membrane surface chemistry.
Abdul Wahab Mohammad - One of the best experts on this subject based on the ideXlab platform.
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Effect of solution chemistry on flux decline during high concentration protein ultrafiltration through a Hydrophilic Membrane
Chemical Engineering Journal, 2010Co-Authors: Ying Pei Lim, Abdul Wahab MohammadAbstract:Abstract The potential use of ultrafiltration (UF) in food industry has been well established. However there have been very few in-depth studies in understanding the fouling phenomena during the UF of food proteins, especially the random-coil type. In this study, the influence of solution chemistry on the extent of fouling and the associate fouling mechanism during UF has been investigated using concentrated gelatin with a Hydrophilic regenerated cellulose acetate Membrane (30 kDa MWCO). It was found that there was insignificant fouling under static condition, but severe fouling was observed during the dynamic filtration. The maximum flux decline rate was obtained at the isoelectric point (IEP) of gelatin, suggesting complementary electrostatically driven fouling. Addition of salt increased flux at pH values near the IEP but had a negative effect at pH above or below the IEP. The experimental data showed that both protein–protein and protein–Membrane interactions influenced the gelatin ultrafiltration performance. The experimental data were fitted well into the fouling models thereby demonstrating that the solution chemistry influenced the fouling mechanism in gelatin ultrafiltration.
M. Essalhi - One of the best experts on this subject based on the ideXlab platform.
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application of a porous composite hydrophobic Hydrophilic Membrane in desalination by air gap and liquid gap Membrane distillation a comparative study
Separation and Purification Technology, 2014Co-Authors: M. Essalhi, Mohamed KhayetAbstract:Abstract A first attempt was carried out comparing the two Membrane distillation (MD) configurations, liquid gap (LGMD) and air gap (AGMD), using a porous composite hydrophobic/Hydrophilic Membrane, the same system and the same MD operating parameters. The surface modified Membrane was prepared by the phase inversion technique in a single casting step using a fluorinated surface modifying macromolecule (SMM). Different Membrane characterization techniques were applied. MD experiments were performed at different feed temperatures and sodium chloride aqueous solutions. The permeate fluxes were found to be slightly higher (2.2–6.5%) for LGMD compared to that of AGMD although the resistance to mass transfer in LGMD is higher due to the presence of the liquid permeate layer between the Membrane and the cooling solid surface. This observed enhancement is attributed partly to the small established distance between the liquid/vapor interfaces at both side of the hydrophobic thin top-layer of the Membrane in LGMD configuration, and the higher thermal conductivity of water, which is an order of magnitude higher than that of air, resulting in higher heat transfer coefficient of the permeate in LGMD. The salt rejection factors were found to be almost similar for both MD variants and higher than 99.61%. Compared to AGMD, the thermal efficiency is higher for LGMD, whereas the specific internal heat loss is lower. A linear increase of the thermal efficiency with the feed inlet temperature was observed for both MD configurations. The global heat transfer coefficient and the heat transfer of the permeate Membrane side were also found to be greater for LGMD. The temperature polarization effect was found to be slightly higher for AGMD, whereas the concentration polarization effect was slightly higher for LGMD due to its higher permeate flux. In general, the LGMD proved to be more attractive than AGMD for desalination when using bi-layered hydrophobic/Hydrophilic Membranes.
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Application of a porous composite hydrophobic/Hydrophilic Membrane in desalination by air gap and liquid gap Membrane distillation: A comparative study
Separation and Purification Technology, 2014Co-Authors: M. Essalhi, Mohamed KhayetAbstract:Abstract A first attempt was carried out comparing the two Membrane distillation (MD) configurations, liquid gap (LGMD) and air gap (AGMD), using a porous composite hydrophobic/Hydrophilic Membrane, the same system and the same MD operating parameters. The surface modified Membrane was prepared by the phase inversion technique in a single casting step using a fluorinated surface modifying macromolecule (SMM). Different Membrane characterization techniques were applied. MD experiments were performed at different feed temperatures and sodium chloride aqueous solutions. The permeate fluxes were found to be slightly higher (2.2–6.5%) for LGMD compared to that of AGMD although the resistance to mass transfer in LGMD is higher due to the presence of the liquid permeate layer between the Membrane and the cooling solid surface. This observed enhancement is attributed partly to the small established distance between the liquid/vapor interfaces at both side of the hydrophobic thin top-layer of the Membrane in LGMD configuration, and the higher thermal conductivity of water, which is an order of magnitude higher than that of air, resulting in higher heat transfer coefficient of the permeate in LGMD. The salt rejection factors were found to be almost similar for both MD variants and higher than 99.61%. Compared to AGMD, the thermal efficiency is higher for LGMD, whereas the specific internal heat loss is lower. A linear increase of the thermal efficiency with the feed inlet temperature was observed for both MD configurations. The global heat transfer coefficient and the heat transfer of the permeate Membrane side were also found to be greater for LGMD. The temperature polarization effect was found to be slightly higher for AGMD, whereas the concentration polarization effect was slightly higher for LGMD due to its higher permeate flux. In general, the LGMD proved to be more attractive than AGMD for desalination when using bi-layered hydrophobic/Hydrophilic Membranes.
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surface segregation of fluorinated modifying macromolecule for hydrophobic Hydrophilic Membrane preparation and application in air gap and direct contact Membrane distillation
Journal of Membrane Science, 2012Co-Authors: M. Essalhi, Mohamed KhayetAbstract:A fluorinated surface modifying macromolecule (SMM) was synthesized and blended into the casting solution of polyetherimide used as host polymer. A composite porous hydrophobic/Hydrophilic Membrane was prepared by the phase inversion technique in a single casting step. The Membrane was characterized by different techniques. During Membrane formation, SMM migrates to the top Membrane surface increasing its hydrophobicity and decreasing its pore size, nodule size and roughness parameters. The thickness of the porous hydrophobic top layer was found to be around 4 mu m. The Membrane was used for desalination by air gap Membrane distillation and direct contact Membrane distillation. The experiments were performed for different sodium chloride aqueous solutions and various operating conditions. The water production rate was found to be high for direct contact Membrane distillation because of the low resistance to mass transport achieved by the diminution of the water vapour transport path length through the hydrophobic thin top-layer of the Membrane.
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Surface segregation of fluorinated modifying macromolecule for hydrophobic/Hydrophilic Membrane preparation and application in air gap and direct contact Membrane distillation
Journal of Membrane Science, 2012Co-Authors: M. Essalhi, Mohamed KhayetAbstract:A fluorinated surface modifying macromolecule (SMM) was synthesized and blended into the casting solution of polyetherimide used as host polymer. A composite porous hydrophobic/Hydrophilic Membrane was prepared by the phase inversion technique in a single casting step. The Membrane was characterized by different techniques. During Membrane formation, SMM migrates to the top Membrane surface increasing its hydrophobicity and decreasing its pore size, nodule size and roughness parameters. The thickness of the porous hydrophobic top layer was found to be around 4 mu m. The Membrane was used for desalination by air gap Membrane distillation and direct contact Membrane distillation. The experiments were performed for different sodium chloride aqueous solutions and various operating conditions. The water production rate was found to be high for direct contact Membrane distillation because of the low resistance to mass transport achieved by the diminution of the water vapour transport path length through the hydrophobic thin top-layer of the Membrane.
Ajay Mandal - One of the best experts on this subject based on the ideXlab platform.
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Optimal synthesis, characterization and antifouling performance of Pluronic F127/bentonite-based super-Hydrophilic polyvinyl chloride ultrafiltration Membrane for enhanced oilfield produced water treatment
Journal of Industrial and Engineering Chemistry, 2020Co-Authors: Tausif Ahmad, Chandan Guria, Ajay MandalAbstract:Abstract Pluronic F127 (PF127-) and PF127/bentonite-blended PVC ultrafiltration Membranes are prepared in salt coagulation baths involving NaCl, KCl, NH4Cl, MgCl2 and CaCl2. Saturated KCl-coagulation bath delivers super-Hydrophilic Membrane with improved surface-porosity (10.64 %), pore density (49.26 μm−2), roughness (51.12 nm) and Hydrophilicity (contact angle
