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Misni Misran - One of the best experts on this subject based on the ideXlab platform.
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vesicles in fatty Acid Salt fatty Acid stabilized o w emulsion emulsion structure and rheology
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004Co-Authors: Boris B. Niraula, Tiong Ngiik Seng, Misni MisranAbstract:Abstract Texture and rheology properties of fatty Acid Salt-fatty Acid mixture stabilized oil–water (o/w) emulsions are being explored. While NaOH solution was introduced as aqueous phase, oil phase contained in it dissolved lauric Acid. When these oil and water phases are brought in contact, a portion of lauric Acid transforms into sodium laurate in situ via Acid–base reaction, the combination of which at a certain threshold concentration and above is believed to act as emulsifier in stabilizing the given o/w emulsion system. Light microscopy under cross polarizing conditions suggested that in addition to the formation of surfactant stabilized emulsion droplets, formation of molecular aggregates of vesicle type is imminent in these conditions, both the size and number density of which is found to be a function of emulsifier concentration ratio. The concentration of emulsifier (sodium laurate–lauric Acid) is being assessed in this work indirectly as a function of NaOH concentration, due to the problem associated with its quantification. Non or a very small number of vesicles was observed at NaOH concentration below 0.4 M, whilst in the presence of 0.4–0.8 M NaOH the vesicle population increased substantially. While vesicle population density decreased past 0.8 M NaOH, their size increased with NaOH concentration from 0.8 to 1 M. These observations suggested that sodium laurate–lauric Acid concentration ratio that corresponds to 0.6–0.8 M NaOH is the optimum NaOH concentration at which maximum vesicle number density is observed. As far as rheology properties are concerned, at any given γ , in the absence of NaOH, the η of the oil solubilized lauric Acid was found to be much lower than the η of corresponding sodium laurate–lauric Acid stabilized o/w emulsion. Though η( γ ) profiles of sodium laurate–lauric Acid stabilized o/w emulsion was not a linear function under the given sets of experimental conditions, at all conditions η strongly depended on sodium laurate–lauric Acid concentrations (concentration of NaOH in this case). What more is that at any given γ , the η was observed to be maximum at sodium laurate–lauric Acid concentration ratio that corresponded to 0.8 M NaOH, a situation which corresponds to the presence of the maximum vesicle number density. In addition to η, in the presence of 0.8 M NaOH, higher values of σY was observed, implying that at this particular NaOH concentration these emulsions possessed greater degree of emulsion structuring compared to other NaOH concentrations. These observations lead to the conclusion that sodium laurate concentration plays a great role in the formation of fatty Acid Salt vesicles, that under the given set of conditions sodium laurate–lauric Acid concentration corresponding to 0.8 M NaOH is the optimum concentration at which maximum number of vesicles are produced, and that rheology property of these emulsions depend not only on emulsion droplets but also on the vesicle number density and size. Test on oscillatory shear mode also suggested that much like o/w emulsions stabilized with other type surfactant, the viscoelastic properties of these sodium laurate–lauric Acid stabilized o/w emulsions depended highly on surfactant concentration. The fact that G″ response was dominant over G′ response at all measured frequency and sodium laurate–lauric Acid concentration, it is evident that viscous property dominated over elastic property in these emulsion. The good news is that improved elastic property is observed at sodium laurate–lauric Acid concentration that corresponded to 0.6–0.8 M NaOH. And not only, in the presence of 0.8 M NaOH, while G″ response of these samples was dominant over G′ response at low ϖ domain, the dynamic moduli crossed-over at around 2 Hz, past which the G′ response became dominant over G″. This implies that, at this particular surfactant concentration, emulsions stabilized with sodium laurate–laurate mixture displays an excellent viscoelastic property pertaining to emulsions used in pharmaceutical and cosmetic products. This further suggests that in the presence of 0.8 M NaOH these o/w emulsion both spread easily and stabilized better as well as possess long storage stability and shelf life. With these dynamic moduli responses it is not surprising that the δ of these sodium laurate–lauric Acid stabilized emulsions decreased with NaOH concentration from 0.4 to 0.8 M. The fact that these emulsion showed smallest δ in the presence of 0.8 M NaOH as opposed to other NaOH concentrations, it is evident that solid-like elastic property of these emulsions is enhanced and improved at this NaOH concentration. As far as oil type is concerned mineral oil based systems showed better rheology properties compared to corresponding paraffin oil based systems.
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Vesicles in fatty Acid Salt-fatty Acid stabilized o/w emulsion - Emulsion structure and rheology
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004Co-Authors: Boris B. Niraula, Tiong Ngiik Seng, Misni MisranAbstract:Texture and rheology properties of fatty Acid Salt-fatty Acid mixture stabilized oil-water (o/w) emulsions are being explored. While NaOH solution was introduced as aqueous phase, oil phase contained in it dissolved lauric Acid. When these oil and water phases are brought in contact, a portion of lauric Acid transforms into sodium laurate in situ via Acid-base reaction, the combination of which at a certain threshold concentration and above is believed to act as emulsifier in stabilizing the given o/w emulsion system. Light microscopy under cross polarizing conditions suggested that in addition to the formation of surfactant stabilized emulsion droplets, formation of molecular aggregates of vesicle type is imminent in these conditions, both the size and number density of which is found to be a function of emulsifier concentration ratio. The concentration of emulsifier (sodium laurate-lauric Acid) is being assessed in this work indirectly as a function of NaOH concentration, due to the problem associated with its quantification. Non or a very small number of vesicles was observed at NaOH concentration below 0.4M, whilst in the presence of 0.4-0.8M NaOH the vesicle population increased substantially. While vesicle population density decreased past 0.8M NaOH, their size increased with NaOH concentration from 0.8 to 1M. These observations suggested that sodium laurate-lauric Acid concentration ratio that corresponds to 0.6-0.8M NaOH is the optimum NaOH concentration at which maximum vesicle number density is observed. As far as rheology properties are concerned, at any given γ̇, in the absence of NaOH, the η of the oil solubilized lauric Acid was found to be much lower than the η of corresponding sodium laurate-lauric Acid stabilized o/w emulsion. Though η(γ̇) profiles of sodium laurate-lauric Acid stabilized o/w emulsion was not a linear function under the given sets of experimental conditions, at all conditions η strongly depended on sodium laurate-lauric Acid concentrations (concentration of NaOH in this case). What more is that at any given γ̇, the η was observed to be maximum at sodium laurate-lauric Acid concentration ratio that corresponded to 0.8M NaOH, a situation which corresponds to the presence of the maximum vesicle number density. In addition to η, in the presence of 0.8M NaOH, higher values of σYwas observed, implying that at this particular NaOH concentration these emulsions possessed greater degree of emulsion structuring compared to other NaOH concentrations. These observations lead to the conclusion that sodium laurate concentration plays a great role in the formation of fatty Acid Salt vesicles, that under the given set of conditions sodium laurate-lauric Acid concentration corresponding to 0.8M NaOH is the optimum concentration at which maximum number of vesicles are produced, and that rheology property of these emulsions depend not only on emulsion droplets but also on the vesicle number density and size. Test on oscillatory shear mode also suggested that much like o/w emulsions stabilized with other type surfactant, the viscoelastic properties of these sodium laurate-lauric Acid stabilized o/w emulsions depended highly on surfactant concentration. The fact that G″ response was dominant over G′ response at all measured frequency and sodium laurate-lauric Acid concentration, it is evident that viscous property dominated over elastic property in these emulsion. The good news is that improved elastic property is observed at sodium laurate-lauric Acid concentration that corresponded to 0.6-0.8M NaOH. And not only, in the presence of 0.8M NaOH, while G″ response of these samples was dominant over G′ response at low domain, the dynamic moduli crossed-over at around 2Hz, past which the G′ response became dominant over G″. This implies that, at this particular surfactant concentration, emulsions stabilized with sodium laurate-laurate mixture displays an excellent viscoelastic property pertaining to emulsions used in pharmaceutical and cosmetic products. This further suggests that in the presence of 0.8M NaOH these o/w emulsion both spread easily and stabilized better as well as possess long storage stability and shelf life. With these dynamic moduli responses it is not surprising that the δ of these sodium laurate-lauric Acid stabilized emulsions decreased with NaOH concentration from 0.4 to 0.8M. The fact that these emulsion showed smallest δ in the presence of 0.8M NaOH as opposed to other NaOH concentrations, it is evident that solid-like elastic property of these emulsions is enhanced and improved at this NaOH concentration. As far as oil type is concerned mineral oil based systems showed better rheology properties compared to corresponding paraffin oil based systems. © 2004 Elsevier B.V. All rights reserved.
Boris B. Niraula - One of the best experts on this subject based on the ideXlab platform.
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vesicles in fatty Acid Salt fatty Acid stabilized o w emulsion emulsion structure and rheology
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004Co-Authors: Boris B. Niraula, Tiong Ngiik Seng, Misni MisranAbstract:Abstract Texture and rheology properties of fatty Acid Salt-fatty Acid mixture stabilized oil–water (o/w) emulsions are being explored. While NaOH solution was introduced as aqueous phase, oil phase contained in it dissolved lauric Acid. When these oil and water phases are brought in contact, a portion of lauric Acid transforms into sodium laurate in situ via Acid–base reaction, the combination of which at a certain threshold concentration and above is believed to act as emulsifier in stabilizing the given o/w emulsion system. Light microscopy under cross polarizing conditions suggested that in addition to the formation of surfactant stabilized emulsion droplets, formation of molecular aggregates of vesicle type is imminent in these conditions, both the size and number density of which is found to be a function of emulsifier concentration ratio. The concentration of emulsifier (sodium laurate–lauric Acid) is being assessed in this work indirectly as a function of NaOH concentration, due to the problem associated with its quantification. Non or a very small number of vesicles was observed at NaOH concentration below 0.4 M, whilst in the presence of 0.4–0.8 M NaOH the vesicle population increased substantially. While vesicle population density decreased past 0.8 M NaOH, their size increased with NaOH concentration from 0.8 to 1 M. These observations suggested that sodium laurate–lauric Acid concentration ratio that corresponds to 0.6–0.8 M NaOH is the optimum NaOH concentration at which maximum vesicle number density is observed. As far as rheology properties are concerned, at any given γ , in the absence of NaOH, the η of the oil solubilized lauric Acid was found to be much lower than the η of corresponding sodium laurate–lauric Acid stabilized o/w emulsion. Though η( γ ) profiles of sodium laurate–lauric Acid stabilized o/w emulsion was not a linear function under the given sets of experimental conditions, at all conditions η strongly depended on sodium laurate–lauric Acid concentrations (concentration of NaOH in this case). What more is that at any given γ , the η was observed to be maximum at sodium laurate–lauric Acid concentration ratio that corresponded to 0.8 M NaOH, a situation which corresponds to the presence of the maximum vesicle number density. In addition to η, in the presence of 0.8 M NaOH, higher values of σY was observed, implying that at this particular NaOH concentration these emulsions possessed greater degree of emulsion structuring compared to other NaOH concentrations. These observations lead to the conclusion that sodium laurate concentration plays a great role in the formation of fatty Acid Salt vesicles, that under the given set of conditions sodium laurate–lauric Acid concentration corresponding to 0.8 M NaOH is the optimum concentration at which maximum number of vesicles are produced, and that rheology property of these emulsions depend not only on emulsion droplets but also on the vesicle number density and size. Test on oscillatory shear mode also suggested that much like o/w emulsions stabilized with other type surfactant, the viscoelastic properties of these sodium laurate–lauric Acid stabilized o/w emulsions depended highly on surfactant concentration. The fact that G″ response was dominant over G′ response at all measured frequency and sodium laurate–lauric Acid concentration, it is evident that viscous property dominated over elastic property in these emulsion. The good news is that improved elastic property is observed at sodium laurate–lauric Acid concentration that corresponded to 0.6–0.8 M NaOH. And not only, in the presence of 0.8 M NaOH, while G″ response of these samples was dominant over G′ response at low ϖ domain, the dynamic moduli crossed-over at around 2 Hz, past which the G′ response became dominant over G″. This implies that, at this particular surfactant concentration, emulsions stabilized with sodium laurate–laurate mixture displays an excellent viscoelastic property pertaining to emulsions used in pharmaceutical and cosmetic products. This further suggests that in the presence of 0.8 M NaOH these o/w emulsion both spread easily and stabilized better as well as possess long storage stability and shelf life. With these dynamic moduli responses it is not surprising that the δ of these sodium laurate–lauric Acid stabilized emulsions decreased with NaOH concentration from 0.4 to 0.8 M. The fact that these emulsion showed smallest δ in the presence of 0.8 M NaOH as opposed to other NaOH concentrations, it is evident that solid-like elastic property of these emulsions is enhanced and improved at this NaOH concentration. As far as oil type is concerned mineral oil based systems showed better rheology properties compared to corresponding paraffin oil based systems.
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Vesicles in fatty Acid Salt-fatty Acid stabilized o/w emulsion - Emulsion structure and rheology
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004Co-Authors: Boris B. Niraula, Tiong Ngiik Seng, Misni MisranAbstract:Texture and rheology properties of fatty Acid Salt-fatty Acid mixture stabilized oil-water (o/w) emulsions are being explored. While NaOH solution was introduced as aqueous phase, oil phase contained in it dissolved lauric Acid. When these oil and water phases are brought in contact, a portion of lauric Acid transforms into sodium laurate in situ via Acid-base reaction, the combination of which at a certain threshold concentration and above is believed to act as emulsifier in stabilizing the given o/w emulsion system. Light microscopy under cross polarizing conditions suggested that in addition to the formation of surfactant stabilized emulsion droplets, formation of molecular aggregates of vesicle type is imminent in these conditions, both the size and number density of which is found to be a function of emulsifier concentration ratio. The concentration of emulsifier (sodium laurate-lauric Acid) is being assessed in this work indirectly as a function of NaOH concentration, due to the problem associated with its quantification. Non or a very small number of vesicles was observed at NaOH concentration below 0.4M, whilst in the presence of 0.4-0.8M NaOH the vesicle population increased substantially. While vesicle population density decreased past 0.8M NaOH, their size increased with NaOH concentration from 0.8 to 1M. These observations suggested that sodium laurate-lauric Acid concentration ratio that corresponds to 0.6-0.8M NaOH is the optimum NaOH concentration at which maximum vesicle number density is observed. As far as rheology properties are concerned, at any given γ̇, in the absence of NaOH, the η of the oil solubilized lauric Acid was found to be much lower than the η of corresponding sodium laurate-lauric Acid stabilized o/w emulsion. Though η(γ̇) profiles of sodium laurate-lauric Acid stabilized o/w emulsion was not a linear function under the given sets of experimental conditions, at all conditions η strongly depended on sodium laurate-lauric Acid concentrations (concentration of NaOH in this case). What more is that at any given γ̇, the η was observed to be maximum at sodium laurate-lauric Acid concentration ratio that corresponded to 0.8M NaOH, a situation which corresponds to the presence of the maximum vesicle number density. In addition to η, in the presence of 0.8M NaOH, higher values of σYwas observed, implying that at this particular NaOH concentration these emulsions possessed greater degree of emulsion structuring compared to other NaOH concentrations. These observations lead to the conclusion that sodium laurate concentration plays a great role in the formation of fatty Acid Salt vesicles, that under the given set of conditions sodium laurate-lauric Acid concentration corresponding to 0.8M NaOH is the optimum concentration at which maximum number of vesicles are produced, and that rheology property of these emulsions depend not only on emulsion droplets but also on the vesicle number density and size. Test on oscillatory shear mode also suggested that much like o/w emulsions stabilized with other type surfactant, the viscoelastic properties of these sodium laurate-lauric Acid stabilized o/w emulsions depended highly on surfactant concentration. The fact that G″ response was dominant over G′ response at all measured frequency and sodium laurate-lauric Acid concentration, it is evident that viscous property dominated over elastic property in these emulsion. The good news is that improved elastic property is observed at sodium laurate-lauric Acid concentration that corresponded to 0.6-0.8M NaOH. And not only, in the presence of 0.8M NaOH, while G″ response of these samples was dominant over G′ response at low domain, the dynamic moduli crossed-over at around 2Hz, past which the G′ response became dominant over G″. This implies that, at this particular surfactant concentration, emulsions stabilized with sodium laurate-laurate mixture displays an excellent viscoelastic property pertaining to emulsions used in pharmaceutical and cosmetic products. This further suggests that in the presence of 0.8M NaOH these o/w emulsion both spread easily and stabilized better as well as possess long storage stability and shelf life. With these dynamic moduli responses it is not surprising that the δ of these sodium laurate-lauric Acid stabilized emulsions decreased with NaOH concentration from 0.4 to 0.8M. The fact that these emulsion showed smallest δ in the presence of 0.8M NaOH as opposed to other NaOH concentrations, it is evident that solid-like elastic property of these emulsions is enhanced and improved at this NaOH concentration. As far as oil type is concerned mineral oil based systems showed better rheology properties compared to corresponding paraffin oil based systems. © 2004 Elsevier B.V. All rights reserved.
Tiong Ngiik Seng - One of the best experts on this subject based on the ideXlab platform.
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vesicles in fatty Acid Salt fatty Acid stabilized o w emulsion emulsion structure and rheology
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004Co-Authors: Boris B. Niraula, Tiong Ngiik Seng, Misni MisranAbstract:Abstract Texture and rheology properties of fatty Acid Salt-fatty Acid mixture stabilized oil–water (o/w) emulsions are being explored. While NaOH solution was introduced as aqueous phase, oil phase contained in it dissolved lauric Acid. When these oil and water phases are brought in contact, a portion of lauric Acid transforms into sodium laurate in situ via Acid–base reaction, the combination of which at a certain threshold concentration and above is believed to act as emulsifier in stabilizing the given o/w emulsion system. Light microscopy under cross polarizing conditions suggested that in addition to the formation of surfactant stabilized emulsion droplets, formation of molecular aggregates of vesicle type is imminent in these conditions, both the size and number density of which is found to be a function of emulsifier concentration ratio. The concentration of emulsifier (sodium laurate–lauric Acid) is being assessed in this work indirectly as a function of NaOH concentration, due to the problem associated with its quantification. Non or a very small number of vesicles was observed at NaOH concentration below 0.4 M, whilst in the presence of 0.4–0.8 M NaOH the vesicle population increased substantially. While vesicle population density decreased past 0.8 M NaOH, their size increased with NaOH concentration from 0.8 to 1 M. These observations suggested that sodium laurate–lauric Acid concentration ratio that corresponds to 0.6–0.8 M NaOH is the optimum NaOH concentration at which maximum vesicle number density is observed. As far as rheology properties are concerned, at any given γ , in the absence of NaOH, the η of the oil solubilized lauric Acid was found to be much lower than the η of corresponding sodium laurate–lauric Acid stabilized o/w emulsion. Though η( γ ) profiles of sodium laurate–lauric Acid stabilized o/w emulsion was not a linear function under the given sets of experimental conditions, at all conditions η strongly depended on sodium laurate–lauric Acid concentrations (concentration of NaOH in this case). What more is that at any given γ , the η was observed to be maximum at sodium laurate–lauric Acid concentration ratio that corresponded to 0.8 M NaOH, a situation which corresponds to the presence of the maximum vesicle number density. In addition to η, in the presence of 0.8 M NaOH, higher values of σY was observed, implying that at this particular NaOH concentration these emulsions possessed greater degree of emulsion structuring compared to other NaOH concentrations. These observations lead to the conclusion that sodium laurate concentration plays a great role in the formation of fatty Acid Salt vesicles, that under the given set of conditions sodium laurate–lauric Acid concentration corresponding to 0.8 M NaOH is the optimum concentration at which maximum number of vesicles are produced, and that rheology property of these emulsions depend not only on emulsion droplets but also on the vesicle number density and size. Test on oscillatory shear mode also suggested that much like o/w emulsions stabilized with other type surfactant, the viscoelastic properties of these sodium laurate–lauric Acid stabilized o/w emulsions depended highly on surfactant concentration. The fact that G″ response was dominant over G′ response at all measured frequency and sodium laurate–lauric Acid concentration, it is evident that viscous property dominated over elastic property in these emulsion. The good news is that improved elastic property is observed at sodium laurate–lauric Acid concentration that corresponded to 0.6–0.8 M NaOH. And not only, in the presence of 0.8 M NaOH, while G″ response of these samples was dominant over G′ response at low ϖ domain, the dynamic moduli crossed-over at around 2 Hz, past which the G′ response became dominant over G″. This implies that, at this particular surfactant concentration, emulsions stabilized with sodium laurate–laurate mixture displays an excellent viscoelastic property pertaining to emulsions used in pharmaceutical and cosmetic products. This further suggests that in the presence of 0.8 M NaOH these o/w emulsion both spread easily and stabilized better as well as possess long storage stability and shelf life. With these dynamic moduli responses it is not surprising that the δ of these sodium laurate–lauric Acid stabilized emulsions decreased with NaOH concentration from 0.4 to 0.8 M. The fact that these emulsion showed smallest δ in the presence of 0.8 M NaOH as opposed to other NaOH concentrations, it is evident that solid-like elastic property of these emulsions is enhanced and improved at this NaOH concentration. As far as oil type is concerned mineral oil based systems showed better rheology properties compared to corresponding paraffin oil based systems.
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Vesicles in fatty Acid Salt-fatty Acid stabilized o/w emulsion - Emulsion structure and rheology
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004Co-Authors: Boris B. Niraula, Tiong Ngiik Seng, Misni MisranAbstract:Texture and rheology properties of fatty Acid Salt-fatty Acid mixture stabilized oil-water (o/w) emulsions are being explored. While NaOH solution was introduced as aqueous phase, oil phase contained in it dissolved lauric Acid. When these oil and water phases are brought in contact, a portion of lauric Acid transforms into sodium laurate in situ via Acid-base reaction, the combination of which at a certain threshold concentration and above is believed to act as emulsifier in stabilizing the given o/w emulsion system. Light microscopy under cross polarizing conditions suggested that in addition to the formation of surfactant stabilized emulsion droplets, formation of molecular aggregates of vesicle type is imminent in these conditions, both the size and number density of which is found to be a function of emulsifier concentration ratio. The concentration of emulsifier (sodium laurate-lauric Acid) is being assessed in this work indirectly as a function of NaOH concentration, due to the problem associated with its quantification. Non or a very small number of vesicles was observed at NaOH concentration below 0.4M, whilst in the presence of 0.4-0.8M NaOH the vesicle population increased substantially. While vesicle population density decreased past 0.8M NaOH, their size increased with NaOH concentration from 0.8 to 1M. These observations suggested that sodium laurate-lauric Acid concentration ratio that corresponds to 0.6-0.8M NaOH is the optimum NaOH concentration at which maximum vesicle number density is observed. As far as rheology properties are concerned, at any given γ̇, in the absence of NaOH, the η of the oil solubilized lauric Acid was found to be much lower than the η of corresponding sodium laurate-lauric Acid stabilized o/w emulsion. Though η(γ̇) profiles of sodium laurate-lauric Acid stabilized o/w emulsion was not a linear function under the given sets of experimental conditions, at all conditions η strongly depended on sodium laurate-lauric Acid concentrations (concentration of NaOH in this case). What more is that at any given γ̇, the η was observed to be maximum at sodium laurate-lauric Acid concentration ratio that corresponded to 0.8M NaOH, a situation which corresponds to the presence of the maximum vesicle number density. In addition to η, in the presence of 0.8M NaOH, higher values of σYwas observed, implying that at this particular NaOH concentration these emulsions possessed greater degree of emulsion structuring compared to other NaOH concentrations. These observations lead to the conclusion that sodium laurate concentration plays a great role in the formation of fatty Acid Salt vesicles, that under the given set of conditions sodium laurate-lauric Acid concentration corresponding to 0.8M NaOH is the optimum concentration at which maximum number of vesicles are produced, and that rheology property of these emulsions depend not only on emulsion droplets but also on the vesicle number density and size. Test on oscillatory shear mode also suggested that much like o/w emulsions stabilized with other type surfactant, the viscoelastic properties of these sodium laurate-lauric Acid stabilized o/w emulsions depended highly on surfactant concentration. The fact that G″ response was dominant over G′ response at all measured frequency and sodium laurate-lauric Acid concentration, it is evident that viscous property dominated over elastic property in these emulsion. The good news is that improved elastic property is observed at sodium laurate-lauric Acid concentration that corresponded to 0.6-0.8M NaOH. And not only, in the presence of 0.8M NaOH, while G″ response of these samples was dominant over G′ response at low domain, the dynamic moduli crossed-over at around 2Hz, past which the G′ response became dominant over G″. This implies that, at this particular surfactant concentration, emulsions stabilized with sodium laurate-laurate mixture displays an excellent viscoelastic property pertaining to emulsions used in pharmaceutical and cosmetic products. This further suggests that in the presence of 0.8M NaOH these o/w emulsion both spread easily and stabilized better as well as possess long storage stability and shelf life. With these dynamic moduli responses it is not surprising that the δ of these sodium laurate-lauric Acid stabilized emulsions decreased with NaOH concentration from 0.4 to 0.8M. The fact that these emulsion showed smallest δ in the presence of 0.8M NaOH as opposed to other NaOH concentrations, it is evident that solid-like elastic property of these emulsions is enhanced and improved at this NaOH concentration. As far as oil type is concerned mineral oil based systems showed better rheology properties compared to corresponding paraffin oil based systems. © 2004 Elsevier B.V. All rights reserved.
Jian Gang Lu - One of the best experts on this subject based on the ideXlab platform.
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Amino Acid-Salt-based complex absorbents for CO2 capture in a membrane contactor
Energy and Fuels, 2010Co-Authors: Jian Gang Lu, Fan Fan, Hui Zhang, Yan Ji, Cong LiuAbstract:Phosphate or borate as an activating agent was added into the aqueous glycinate to form amino Acid Salt-based complex absorbents. Capture of CO2 by the complex absorbents was studied theoretically and experimentally using a hollow fiber membrane contactor. Reaction mechanism concerning the activation effect of phosphate and borate was presented theoretically. A mathematical model was developed to simulate mass transfer of the membrane contactor. The effects of absorbent and gas CO2 concentrations on mass transfer flux and CO2 capture efficiency were investigated. Surface tension of the complex absorbents and operational stability of the membrane contactor were also discussed in this work. Results show that the activation follows the sequence B4O72− > PO43− > HPO42− > H2PO4−. The mathematical model was validated by comparing theoretical with experimental data. The mass transfer flux increased almost linearly with the increase of gas CO2 concentration. Surface tension data revealed that the complex absorbents could not wet the membrane micropores. The flux was basically kept constant during the prolonged period of operation. The complex absorbents modified by the phosphates and borates are good potential absorbents for CO2 capture.
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CO2 Capture using activated amino Acid Salt solutions in a membrane contactor
Separation Science and Technology, 2010Co-Authors: Jian Gang Lu, Hui Zhang, Yan Ji, Min Dong ChenAbstract:An activated solution based on amino Acid Salt was proposed as a CO2 absorbent. Piperazine (PZ) was selected as an activating agent and added into the aqueous glycine Salt to form the activated solution. A coupling process, which associated the activated solution with a PP hollow fiber membrane contactor, was set up. An experimental and theoretical analysis for CO2 capture was performed. The performances of CO2 capture by the coupling process were evaluated using the PZ activated solution and the non-activated glycine Salt solution. A numerical model for the simulation of the hollow fiber membrane gas–liquid mass transfer was developed. Typical parameters such as outlet gas phase CO2 concentration, capture efficiency, and mass transfer coefficient for the activated solution were determined experimentally. The effects of operation temperature and liquid CO2-loading on mass transfer coefficient and capture efficiency were discussed in this work. Axial and radial concentration profiles of CO2 in the fiber lumen and mass transfer flux were simulated by the model. Results show that the performances of the PZ activated glycine Salt solution are evidently better than that of the non-activated glycine Salt solution in the membrane contactor for CO2 capture. Elevation of the operation temperatures can enhance the overall mass transfer coefficient. The activated solution can maintain higher capture efficiency especially in the case of high CO2-loadings. The gas phase CO2 concentration with the activated solution is lower than that with the non-activated solution whether along axial or radial distances in the fiber lumen. The model simulation is validated with experimental data.
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Membrane contactor for CO2 absorption applying amino-Acid Salt solutions
Desalination, 2009Co-Authors: Jian Gang Lu, You Fei Zheng, Min Dong ChengAbstract:A novel composite solution based on amino-Acid Salt as a CO2 absorbent was proposed. Coupling process of membrane contactor and the composite solution was investigated. The performance of the coupling was experimentally compared between the single and composite solution. Overall mass transfer coefficients were determined. Effects of various factors such as flow rates and operation temperatures on mass transfer of membrane contactor were studied. Comparison of prediction for overall mass transfer coefficients using a resistance in series model with experimental values was performed. Results show that, performance of the composite solution is evidently better than that of the single solution. The overall mass transfer coefficient with the composite solution is much higher than that with the single solution. Higher operation temperature can enhance mass transfer of membrane contactor. Operation parameters such as flow rates can promote mass transfer, but the promotion is limited. Enhancement of mass transfer relies essentially on chemical reaction. Model values are in good agreement with experimental ones. © 2009 Elsevier B.V. All rights reserved.
Andrey Yaroslavtsev - One of the best experts on this subject based on the ideXlab platform.
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Electrocatalytic and transport properties of hybrid Nafion?? membranes doped with silica and cesium Acid Salt of phosphotungstic Acid in hydrogen fuel cells
Chemical Engineering Journal, 2015Co-Authors: Ekaterina Gerasimova, Aleksander Ukshe, Yury Dobrovolsky, E Safronova, Andrey YaroslavtsevAbstract:This work is devoted to preparation of a hybrid material based on Nafion?? 212 membrane doped with nanoparticles of silica and cesium Acid Salt of phosphotungstic heteropolyAcid. The benefits of this material are concerned with its increased conductivity at low humidity. Conductivity and properties of the membranes were studied as a function of relative humidity under the FC operating regime at room temperature. As compared with the commercial Nafion?? 212 membrane, the MEA based on this material shows a lower power density at 100% relative humidity of the supplied gases (hydrogen, air). As the relative humidity decreases, power density of the cell based on hybrid membrane increases and overruns the performance of the commercial Nafion?? 212 membrane at 100% RH. Explanation of the observed phenomena is proposed.
