The Experts below are selected from a list of 9054 Experts worldwide ranked by ideXlab platform

Isiah M. Warner - One of the best experts on this subject based on the ideXlab platform.

  • open tubular capillary electrochromatography electrospray ionization mass spectrometry using Polymeric Surfactant as a stationary phase coating
    Electrophoresis, 2004
    Co-Authors: Xiaofeng Zhu, Serigne Thiam, Mary W Kamande, Constantina P Kapnissi, Simon M Mwongela, Isiah M. Warner
    Abstract:

    We describe the use of the Polymeric Surfactant poly(sodium undecylenic sulfate) (poly-SUS) as a stationary phase coating in open-tubular capillary electrochromatography (OT-CEC) coupled with electrospray ionization-mass spectrometry (ESI-MS) for the analysis of beta-blocker and benzodiazepine analytes. The production of a Polymeric Surfactant coating on the capillary inner wall involves (i) adsorption of the cationic polymer poly(diallyldimethylammonium chloride) (PDADMAC) to the inner surface of capillary, and (ii) adsorption of the negatively charged poly-SUS onto the cationic polymer layer via strong physical interaction of the two polymer layers. As compared with micellar electrokinetic chromatography (MEKC) coupled with ESI-MS, the main advantage of this proposed method is minimization of introduction of the monomeric or Polymeric Surfactant into the mass spectrometer, thus avoiding the interference of the nonvolatile micelle in ESI-MS. The effects of buffer pH and applied voltage on the separation of the analytes are also discussed. Under optimum conditions, four of the five beta-blockers and four benzodiazepines are separated.

  • separation of achiral and chiral analytes using Polymeric Surfactants with ionic liquids as modifiers in micellar electrokinetic chromatography
    Analytical Chemistry, 2003
    Co-Authors: Simon M Mwongela, Abdulqawi Numan, Nicole L Gill, Rezik A Agbaria, Isiah M. Warner
    Abstract:

    In this study, we report the use of ionic liquids as modifiers in the separation of achiral and chiral analytes in micellar electrokinetic chromatography. In this investigation, Polymeric Surfactants and ionic liquids were added to a low-conducting buffer solution. The Polymeric Surfactants used in this study were poly(sodium N-undecylelinic sulfate) and poly(sodium oleyl-l-leucylvalinate). The ionic liquids used in this study were chosen because of their high conductivity, hydrophobicity, and good solvating properties. Thus, it was expected that these ionic liquids would have the ability to assist in the separation of hydrophobic mixtures while maintaining adequate background current. Three analyte mixtures were separated using various buffer combinations of Polymeric Surfactant and ionic liquids. The ionic liquids were shown to improve the resolution and peak efficiency of the analytes while maintaining adequate background current.

  • open tubular capillary electrochromatography using a Polymeric Surfactant coating
    Electrophoresis, 2003
    Co-Authors: Mary W Kamande, Xiaofeng Zhu, Constantina P Kapnissi, Cevdet Akbay, Isiah M. Warner
    Abstract:

    A stable polyelectrolyte multilayer (PEM) coating was investigated for use in open-tubular capillary electrochromatography (o-CEC). In this approach, the PEM consisted of the cationic polymer of a quaternary ammonium salt, poly(diallyldimethylammonium chloride) and the anionic Polymeric Surfactant, poly(sodium undecylenic sulfate). Both the cationic and anionic polymers were physically adsorbed to the surface of a fused-silica capillary by use of a simple coating procedure. This procedure involved an alternate rinse of the positively and negatively charged polymers. The performance of the PEM coating as a dynamic stationary phase was evaluated by use of electrochromatographic experiments and showed good selectivity for both phenols and benzodiazepines. Reproducibility of the PEM coating was also evaluated by calculating the relative standard deviations (RSDs) of the electroosomotic flow (EOF). The run-to-run and capillary-to-capillary RSD values of the EOF were less than 1.5%. The endurance of the coating was more than 100 runs. The importance of the PEM coating was illustrated by comparing separations on a bare uncoated capillary with the coated capillary. In addition, the chromatographic performance using o-CEC and micellar electrokinetic chromatography (MEKC) was compared for the separation of benzodiazepines.

  • Capillary Electrochromatography of Cholesterol and Its Ester Derivatives
    Analytical Chemistry, 2000
    Co-Authors: Serigne Thiam, Charles W Henry, Shahab A Shamsi, James W. Robinson, Isiah M. Warner
    Abstract:

    Separation of cholesterol and its ester derivatives using micellar electrokinetic chromatography is a challenge due to the extreme hydrophobicity of these compounds. In this work, an isocratic capillary electrochromatography (CEC) method has been developed to separate a complex mixture of cholesterol and its 12-ester derivatives. The proportions of mobile phase (tetrahydrofuran, acetonitrile, water), as well as the effects of acid modifiers, buffer concentrations, voltage, and temperature on the separation of cholesterol derivatives were investigated. Addition of a Polymeric Surfactant, poly(sodium N-undecanoyl-l-glycinate), to the mobile phase reduced migration time and improved resolution of the analytes. The CEC method developed allows baseline separation of a complex mixture of cholesterol and 12 ester derivatives in less than 40 min. Finally, the method is applied to the characterization of cholesterol, cholesterol linoleate, and cholesterol oleate extracted from atherosclerotic plaque deposits in th...

  • Capillary Electrochromatography of Cholesterol and Its Ester Derivatives
    Analytical Chemistry, 2000
    Co-Authors: Serigne Thiam, Charles W Henry, Shahab A Shamsi, James W. Robinson, Isiah M. Warner
    Abstract:

    Separation of cholesterol and its ester derivatives using micellar electrokinetic chromatography is a challenge due to the extreme hydrophobicity of these compounds. In this work, an isocratic capillary electrochromatography (CEC) method has been developed to separate a complex mixture of cholesterol and its 12-ester derivatives. The proportions of mobile phase (tetrahydrofuran, acetonitrile, water), as well as the effects of acid modifiers, buffer concentrations, voltage, and temperature on the separation of cholesterol derivatives were investigated. Addition of a Polymeric Surfactant, poly(sodium N-undecanoyl-l-glycinate), to the mobile phase reduced migration time and improved resolution of the analytes. The CEC method developed allows baseline separation of a complex mixture of cholesterol and 12 ester derivatives in less than 40 min. Finally, the method is applied to the characterization of cholesterol, cholesterol linoleate, and cholesterol oleate extracted from atherosclerotic plaque deposits in th...

Ajay Mandal - One of the best experts on this subject based on the ideXlab platform.

  • oil in water nanoemulsion stabilized by Polymeric Surfactant characterization and properties evaluation for enhanced oil recovery
    European Polymer Journal, 2018
    Co-Authors: Narendra Kumar, Ajay Mandal
    Abstract:

    Abstract Nanoemulsions are kinetically stable colloidal dispersion of oil and aqueous phase with droplet size

  • rheological properties and performance evaluation of synthesized anionic Polymeric Surfactant for its application in enhanced oil recovery
    Polymer, 2017
    Co-Authors: Sudhir Kumar, Ajay Mandal
    Abstract:

    Abstract Polymeric Surfactant is an attractive alternative to conventional Surfactant-polymer system for application in enhanced oil recovery, as it plays dual role of reduction of interfacial tension (IFT) and improvement of mobility ratio. The present paper deals with the synthesis and rheological characterization of a novel Polymeric Surfactant derived from Jatropha oil. Molecular aggregation of polymer in aqueous solution has been confirmed by DLS studies, which increases with increase in concentration. The viscosity results indicate the good shear stability of system at higher shear rate as well as higher temperature for application in conventional oil reservoir. The Polymeric solutions show peculiar behaviour with shear thinning nature at low shear rate and shear thickening nature at higher shear rate because of its unique molecular properties. The viscoelastic properties of the solutions were investigated and it has been found that storage modulus (G′) and loss modulus (G″) follow the Maxwellian fluid behavior. Specific frequency (SF) indicated by the crossing point between G′ and G″ on the viscoelastic curve represents the point of transition between elastic and viscous phases of the Polymeric Surfactant system. The effect of silica nanoparticle on polymer viscosity was also studied and it has been found that introduction of silica nanoparticle dramatically increases the polymer viscosity and stability of the solution with respect to temperature.

  • synthesis and evaluation of physicochemical properties of anionic Polymeric Surfactant derived from jatropha oil for application in enhanced oil recovery
    Journal of Industrial and Engineering Chemistry, 2016
    Co-Authors: Sudhir Kumar, Neha Saxena, Ajay Mandal
    Abstract:

    Abstract In this study an attention has been paid to synthesize polymer grafted anionic Surfactant (PMES) derived from nonedible vegetable oil (Jatropha) for its application in enhanced oil recovery (EOR). The Polymeric Surfactant was prepared by reacting acrylamide monomer with methyl ester sulfonate (MES) synthesized from Jatropha oil by free radical polymerization mechanism. Polymeric Surfactant with properties of both Surfactant and polymer can control the mobility ratio and reduce interfacial tension (IFT), which are desirable for EOR. The synthesized Polymeric Surfactant was characterized through FTIR, 1 H NMR, FESEM, EDX, TGA, DLS analysis. The effectiveness of PMES for chemically enhanced oil recovery process was investigated by measurement of physiochemical properties of its aqueous solution viz. reduction of IFT, wettability alteration and rheological behaviour. Rheological studies shows shear thinning behaviour with apparent viscosity comparable to conventional polymers. The IFT between crude oil and aqueous PMES solution at its critical micelle concentration (CMC) was observed as 2.74 mN/m, which was further reduced to 0.37 mN/m on addition of 2.5 wt% NaCl. Core flooding experiments were conducted in sandpack system, to study the EOR efficiency using the synthesized Polymeric Surfactant and more than 26% additional recovery was observed after usual water flooding. Higher recoveries at higher temperature were observed because of swelling of crude oil and lowering of IFT.

  • surface tension dynamic light scattering and rheological studies of a new Polymeric Surfactant for application in enhanced oil recovery
    Journal of Petroleum Science and Engineering, 2016
    Co-Authors: Nilanjan Pal, K R Babu, Ajay Mandal
    Abstract:

    Abstract The present paper deals with the synthesis of a new Polymeric Surfactant (PMES) and characterization of its aqueous solution for application in enhanced oil recovery. The synthesized Polymeric Surfactant possesses properties of both Surfactant and polymer. Surface tension, particle size distribution and rheological properties of the Polymeric Surfactant have been studied and analyzed under the influence of various factors. IFT was found to decrease with concentration of PMES and salt addition. The reduction of surface tension at optimum salinity is comparable to any commercial Surfactant. DLS measurement showed that hydrodynamic particle diameter generally increased with concentration of PMES due to aggregation of molecules and decreased with salt addition due to disaggregation of molecules. Viscosity was found to increase with increase with PMES concentration but decreased with temperature rise and salt addition. Analysis of rheological data showed that Polymeric Surfactant behaved ideally up to a critical shear rate of 50 s −1 but exhibited shear-thinning or pseudoplastic behavior at higher shear rates. Its viscoelastic properties were studied and showed that storage modulus G′ and loss modulus G″ increased with increasing PMES concentration. Specific frequency (SF) indicated by the crossing point between G′ and G″ on the viscoelastic curve represents the point of transition between elastic and viscous phases of the Polymeric Surfactant system.

  • synthesis and characterization of a new Polymeric Surfactant for chemical enhanced oil recovery
    Korean Journal of Chemical Engineering, 2016
    Co-Authors: K R Babu, V K Saxena, Nilanjan Pal, Ajay Mandal
    Abstract:

    Chemical enhanced oil recovery methods are field proven techniques that improve efficiency and effectiveness of oil recovery. We have synthesized Polymeric Surfactant from vegetable oil (castor oil) for application in chemical enhanced oil recovery. First, an eco-friendly Surfactant, sodium methyl ester sulfonate (SMES) was synthesized from castor oil, and then the Polymeric Surfactant (PMES) was produced by graft co-polymerization reaction using different Surfactant to acrylamide ratios. The synthesized PMES was characterized by FTIR, FE-SEM, EDX, TGA, DLS analysis. The performance of PMES as a chemical agent for enhanced oil recovery was studied by measuring the interfacial tension (IFT) between crude oil and PMES solution, rheological behavior and contact angle against sandstone surface. Addition of sodium chloride in PMES solution reduced the IFT to an ultra-low value (2.0×10-3mN/m). Core flooding experiments were conducted in sandpack system, and 26.5%, 27.8% and 29.1% additional recovery of original oil in place (OOIP) was obtained for 0.5, 0.6 and 0.7mass% of PMES solutions, respectively, after conventional water flooding.

Serigne Thiam - One of the best experts on this subject based on the ideXlab platform.

  • open tubular capillary electrochromatography electrospray ionization mass spectrometry using Polymeric Surfactant as a stationary phase coating
    Electrophoresis, 2004
    Co-Authors: Xiaofeng Zhu, Serigne Thiam, Mary W Kamande, Constantina P Kapnissi, Simon M Mwongela, Isiah M. Warner
    Abstract:

    We describe the use of the Polymeric Surfactant poly(sodium undecylenic sulfate) (poly-SUS) as a stationary phase coating in open-tubular capillary electrochromatography (OT-CEC) coupled with electrospray ionization-mass spectrometry (ESI-MS) for the analysis of beta-blocker and benzodiazepine analytes. The production of a Polymeric Surfactant coating on the capillary inner wall involves (i) adsorption of the cationic polymer poly(diallyldimethylammonium chloride) (PDADMAC) to the inner surface of capillary, and (ii) adsorption of the negatively charged poly-SUS onto the cationic polymer layer via strong physical interaction of the two polymer layers. As compared with micellar electrokinetic chromatography (MEKC) coupled with ESI-MS, the main advantage of this proposed method is minimization of introduction of the monomeric or Polymeric Surfactant into the mass spectrometer, thus avoiding the interference of the nonvolatile micelle in ESI-MS. The effects of buffer pH and applied voltage on the separation of the analytes are also discussed. Under optimum conditions, four of the five beta-blockers and four benzodiazepines are separated.

  • Capillary Electrochromatography of Cholesterol and Its Ester Derivatives
    Analytical Chemistry, 2000
    Co-Authors: Serigne Thiam, Charles W Henry, Shahab A Shamsi, James W. Robinson, Isiah M. Warner
    Abstract:

    Separation of cholesterol and its ester derivatives using micellar electrokinetic chromatography is a challenge due to the extreme hydrophobicity of these compounds. In this work, an isocratic capillary electrochromatography (CEC) method has been developed to separate a complex mixture of cholesterol and its 12-ester derivatives. The proportions of mobile phase (tetrahydrofuran, acetonitrile, water), as well as the effects of acid modifiers, buffer concentrations, voltage, and temperature on the separation of cholesterol derivatives were investigated. Addition of a Polymeric Surfactant, poly(sodium N-undecanoyl-l-glycinate), to the mobile phase reduced migration time and improved resolution of the analytes. The CEC method developed allows baseline separation of a complex mixture of cholesterol and 12 ester derivatives in less than 40 min. Finally, the method is applied to the characterization of cholesterol, cholesterol linoleate, and cholesterol oleate extracted from atherosclerotic plaque deposits in th...

  • Capillary Electrochromatography of Cholesterol and Its Ester Derivatives
    Analytical Chemistry, 2000
    Co-Authors: Serigne Thiam, Charles W Henry, Shahab A Shamsi, James W. Robinson, Isiah M. Warner
    Abstract:

    Separation of cholesterol and its ester derivatives using micellar electrokinetic chromatography is a challenge due to the extreme hydrophobicity of these compounds. In this work, an isocratic capillary electrochromatography (CEC) method has been developed to separate a complex mixture of cholesterol and its 12-ester derivatives. The proportions of mobile phase (tetrahydrofuran, acetonitrile, water), as well as the effects of acid modifiers, buffer concentrations, voltage, and temperature on the separation of cholesterol derivatives were investigated. Addition of a Polymeric Surfactant, poly(sodium N-undecanoyl-l-glycinate), to the mobile phase reduced migration time and improved resolution of the analytes. The CEC method developed allows baseline separation of a complex mixture of cholesterol and 12 ester derivatives in less than 40 min. Finally, the method is applied to the characterization of cholesterol, cholesterol linoleate, and cholesterol oleate extracted from atherosclerotic plaque deposits in th...

Galip Akay - One of the best experts on this subject based on the ideXlab platform.

  • Process intensification in particle technology: flow induced phase inversion in the intensive emulsification of epoxy polymer melts in water
    Journal of Materials Science, 2002
    Co-Authors: L Tong, Galip Akay
    Abstract:

    The flow induced phase inversion phenomenon is applied to the phase inversion emulsification of high molecular weight epoxy polymer melt to obtain sub-micron particles. It is found that molecular Surfactants could not be used to obtain the initial [water-in-polymer melt] emulsion. Polymeric Surfactants, hydrophobically modified water soluble polymers have to be used for this purpose. The molecular structure of the Polymeric Surfactant is important in obtaining smaller emulsion droplets for a given polymer melt. Depending on the processing history, either a ‘powdery dispersion’ containing 10 wt% water or water continuous dispersion can be obtained. Sub-micron epoxy particles can be obtained, even at relatively low Polymeric Surfactant concentrations, by subjecting the [water-in-polymer melt] emulsion to very high deformation rates using a model static mixer called Multiple Expansion Contraction Static Mixer. This mixer is essentially a series of short capillaries separated by flow dividers. In order to provide constant flow rate at very high pressures, an injection moulding machine is used.

  • Process intensification in particle technology: flow induced phase inversion in the intensive emulsification of epoxy polymer melts in water
    Journal of Materials Science, 2002
    Co-Authors: L Tong, Galip Akay
    Abstract:

    The flow induced phase inversion phenomenon is applied to the phase inversion emulsification of high molecular weight epoxy polymer melt to obtain sub-micron particles. It is found that molecular Surfactants could not be used to obtain the initial [water-in-polymer melt] emulsion. Polymeric Surfactants, hydrophobically modified water soluble polymers have to be used for this purpose. The molecular structure of the Polymeric Surfactant is important in obtaining smaller emulsion droplets for a given polymer melt. Depending on the processing history, either a ‘powdery dispersion’ containing 10 wt% water or water continuous dispersion can be obtained. Sub-micron epoxy particles can be obtained, even at relatively low Polymeric Surfactant concentrations, by subjecting the [water-in-polymer melt] emulsion to very high deformation rates using a model static mixer called Multiple Expansion Contraction Static Mixer. This mixer is essentially a series of short capillaries separated by flow dividers. In order to provide constant flow rate at very high pressures, an injection moulding machine is used.

L Tong - One of the best experts on this subject based on the ideXlab platform.

  • Process intensification in particle technology: flow induced phase inversion in the intensive emulsification of epoxy polymer melts in water
    Journal of Materials Science, 2002
    Co-Authors: L Tong, Galip Akay
    Abstract:

    The flow induced phase inversion phenomenon is applied to the phase inversion emulsification of high molecular weight epoxy polymer melt to obtain sub-micron particles. It is found that molecular Surfactants could not be used to obtain the initial [water-in-polymer melt] emulsion. Polymeric Surfactants, hydrophobically modified water soluble polymers have to be used for this purpose. The molecular structure of the Polymeric Surfactant is important in obtaining smaller emulsion droplets for a given polymer melt. Depending on the processing history, either a ‘powdery dispersion’ containing 10 wt% water or water continuous dispersion can be obtained. Sub-micron epoxy particles can be obtained, even at relatively low Polymeric Surfactant concentrations, by subjecting the [water-in-polymer melt] emulsion to very high deformation rates using a model static mixer called Multiple Expansion Contraction Static Mixer. This mixer is essentially a series of short capillaries separated by flow dividers. In order to provide constant flow rate at very high pressures, an injection moulding machine is used.

  • Process intensification in particle technology: flow induced phase inversion in the intensive emulsification of epoxy polymer melts in water
    Journal of Materials Science, 2002
    Co-Authors: L Tong, Galip Akay
    Abstract:

    The flow induced phase inversion phenomenon is applied to the phase inversion emulsification of high molecular weight epoxy polymer melt to obtain sub-micron particles. It is found that molecular Surfactants could not be used to obtain the initial [water-in-polymer melt] emulsion. Polymeric Surfactants, hydrophobically modified water soluble polymers have to be used for this purpose. The molecular structure of the Polymeric Surfactant is important in obtaining smaller emulsion droplets for a given polymer melt. Depending on the processing history, either a ‘powdery dispersion’ containing 10 wt% water or water continuous dispersion can be obtained. Sub-micron epoxy particles can be obtained, even at relatively low Polymeric Surfactant concentrations, by subjecting the [water-in-polymer melt] emulsion to very high deformation rates using a model static mixer called Multiple Expansion Contraction Static Mixer. This mixer is essentially a series of short capillaries separated by flow dividers. In order to provide constant flow rate at very high pressures, an injection moulding machine is used.