The Experts below are selected from a list of 72 Experts worldwide ranked by ideXlab platform

Gerd Buntkowsky - One of the best experts on this subject based on the ideXlab platform.

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation.
    Journal of Physical Chemistry B, 2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048–2.35 mol kg–1). A change in speciation near 0.2 mol kg–1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes–Einstein equation using additional measured solution viscosities. The concentration of r...

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation.
    The journal of physical chemistry. B, 2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048-2.35 mol kg-1). A change in speciation near 0.2 mol kg-1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes-Einstein equation using additional measured solution viscosities. The concentration of reverse micelles and unaggregated C10E6 was calculated from the freezing point depression results using the aggregation numbers obtained from ratio of self-diffusion coefficients. These concentrations indicate that the reverse micelles become smaller in average size and increase in number with increasing temperature without an increase in unaggregated C10E6.

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation
    2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly­(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048–2.35 mol kg–1). A change in speciation near 0.2 mol kg–1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes–Einstein equation using additional measured solution viscosities. The concentration of reverse micelles and unaggregated C10E6 was calculated from the freezing point depression results using the aggregation numbers obtained from ratio of self-diffusion coefficients. These concentrations indicate that the reverse micelles become smaller in average size and increase in number with increasing temperature without an increase in unaggregated C10E6

Markus M. Hoffmann - One of the best experts on this subject based on the ideXlab platform.

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation.
    Journal of Physical Chemistry B, 2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048–2.35 mol kg–1). A change in speciation near 0.2 mol kg–1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes–Einstein equation using additional measured solution viscosities. The concentration of r...

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation.
    The journal of physical chemistry. B, 2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048-2.35 mol kg-1). A change in speciation near 0.2 mol kg-1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes-Einstein equation using additional measured solution viscosities. The concentration of reverse micelles and unaggregated C10E6 was calculated from the freezing point depression results using the aggregation numbers obtained from ratio of self-diffusion coefficients. These concentrations indicate that the reverse micelles become smaller in average size and increase in number with increasing temperature without an increase in unaggregated C10E6.

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation
    2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly­(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048–2.35 mol kg–1). A change in speciation near 0.2 mol kg–1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes–Einstein equation using additional measured solution viscosities. The concentration of reverse micelles and unaggregated C10E6 was calculated from the freezing point depression results using the aggregation numbers obtained from ratio of self-diffusion coefficients. These concentrations indicate that the reverse micelles become smaller in average size and increase in number with increasing temperature without an increase in unaggregated C10E6

Sarah Bothe - One of the best experts on this subject based on the ideXlab platform.

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation.
    Journal of Physical Chemistry B, 2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048–2.35 mol kg–1). A change in speciation near 0.2 mol kg–1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes–Einstein equation using additional measured solution viscosities. The concentration of r...

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation.
    The journal of physical chemistry. B, 2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048-2.35 mol kg-1). A change in speciation near 0.2 mol kg-1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes-Einstein equation using additional measured solution viscosities. The concentration of reverse micelles and unaggregated C10E6 was calculated from the freezing point depression results using the aggregation numbers obtained from ratio of self-diffusion coefficients. These concentrations indicate that the reverse micelles become smaller in average size and increase in number with increasing temperature without an increase in unaggregated C10E6.

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation
    2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly­(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048–2.35 mol kg–1). A change in speciation near 0.2 mol kg–1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes–Einstein equation using additional measured solution viscosities. The concentration of reverse micelles and unaggregated C10E6 was calculated from the freezing point depression results using the aggregation numbers obtained from ratio of self-diffusion coefficients. These concentrations indicate that the reverse micelles become smaller in average size and increase in number with increasing temperature without an increase in unaggregated C10E6

Torsten Gutmann - One of the best experts on this subject based on the ideXlab platform.

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation.
    Journal of Physical Chemistry B, 2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048–2.35 mol kg–1). A change in speciation near 0.2 mol kg–1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes–Einstein equation using additional measured solution viscosities. The concentration of r...

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation.
    The journal of physical chemistry. B, 2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048-2.35 mol kg-1). A change in speciation near 0.2 mol kg-1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes-Einstein equation using additional measured solution viscosities. The concentration of reverse micelles and unaggregated C10E6 was calculated from the freezing point depression results using the aggregation numbers obtained from ratio of self-diffusion coefficients. These concentrations indicate that the reverse micelles become smaller in average size and increase in number with increasing temperature without an increase in unaggregated C10E6.

  • Combining Freezing Point Depression and Self-Diffusion Data for Characterizing Aggregation
    2018
    Co-Authors: Markus M. Hoffmann, Sarah Bothe, Torsten Gutmann, Gerd Buntkowsky
    Abstract:

    The Colligative Property freezing point depression is evaluated as a means for estimating the extent of aggregation for solutions of poly­(ethylene oxide) alcohol (C10E6) nonionic surfactant in cyclohexane. Combined with additional measurements of self-diffusion coefficients, it is shown that both unaggregated C10E6 as well as reverse micelles are significantly present for the entire range of measured C10E6 concentration (0.048–2.35 mol kg–1). A change in speciation near 0.2 mol kg–1 is indicated by the results from both freezing point depression and self-diffusion coefficient measurements. It is shown that average reverse micelle radii and aggregation numbers obtained from the ratio of solvent and C10E6 self-diffusion coefficients are consistent with prior reported results. However, unreasonably small radii for the reverse micelles as well as for the cyclohexane were obtained from analysis of the results by the Stokes–Einstein equation using additional measured solution viscosities. The concentration of reverse micelles and unaggregated C10E6 was calculated from the freezing point depression results using the aggregation numbers obtained from ratio of self-diffusion coefficients. These concentrations indicate that the reverse micelles become smaller in average size and increase in number with increasing temperature without an increase in unaggregated C10E6

Wilhelmsen Øivind - One of the best experts on this subject based on the ideXlab platform.

  • Ice formation and growth in supercooled water–alcohol mixtures: Theory and experiments with dual fiber sensors
    'Elsevier BV', 2020
    Co-Authors: Wahl, Markus Solberg, Aasen Ailo, Hjelme, Dag Roar, Wilhelmsen Øivind
    Abstract:

    Increased knowledge on fluid-solid phase transitions is needed, both when they are undesired and can impair processes operation, and when strict control is required in fields such as food technology, the pharmaceutical industry and cryogenic CO2 capture. We present experimental results and theoretical predictions for the solid-formation and melting temperatures of ice in four binary water–alcohol mixtures containing methanol, ethanol, 1-propanol and 1-butanol. A dual fiber sensor set-up with a fiber Bragg grating sensor and a thin-core interferometer is used to detect the solid-formation. The predictions of melting temperatures with the cubic plus association equation of state combined with an ice model are in good agreement with experiments, but deviations are observed at higher alcohol concentrations. The measured degree of supercooling displays a highly non-linear dependence on the alcohol concentration. A heterogeneous nucleation model is developed to predict the solid-formation temperatures of the binary alcohol–water mixtures. The predictions from this model are in reasonable agreement with the measurements, but follow a qualitatively different trend that results in systematic deviations. In particular, the predicted degree of supercooling is found to be an essentially Colligative Property that increases smoothly with alcohol concentration. Experimental results are also presented for the growth rate of ice crystals in water–ethanol mixtures. For pure water, the measured crystal growth rate is 10.2 cm/s at 16 K supercooling. This is in excellent agreement with previous results from the literature. The crystal growth rate observed in ethanol–water mixtures however, can be orders of magnitude lower, where a mixture with 2% mole fraction ethanol has a growth rate of 2 mm/s. Further work is required to explain the large reduction in crystal growth rate with increasing alcohol concentration and to reproduce the behavior of the solid-formation temperatures with heterogeneous nucleation theory

  • Ice formation and growth in supercooled water–alcohol mixtures: Theory and experiments with dual fiber sensors
    'Elsevier BV', 2020
    Co-Authors: Wahl, Markus Solberg, Aasen Ailo, Hjelme, Dag Roar, Wilhelmsen Øivind
    Abstract:

    Increased knowledge on fluid-solid phase transitions is needed, both when they are undesired and can impair processes operation, and when strict control is required in fields such as food technology, the pharmaceutical industry and cryogenic CO2 capture. We present experimental results and theoretical predictions for the solid-formation and melting temperatures of ice in four binary water–alcohol mixtures containing methanol, ethanol, 1-propanol and 1-butanol. A dual fiber sensor set-up with a fiber Bragg grating sensor and a thin-core interferometer is used to detect the solid-formation. The predictions of melting temperatures with the cubic plus association equation of state combined with an ice model are in good agreement with experiments, but deviations are observed at higher alcohol concentrations. The measured degree of supercooling displays a highly non-linear dependence on the alcohol concentration. A heterogeneous nucleation model is developed to predict the solid-formation temperatures of the binary alcohol–water mixtures. The predictions from this model are in reasonable agreement with the measurements, but follow a qualitatively different trend that results in systematic deviations. In particular, the predicted degree of supercooling is found to be an essentially Colligative Property that increases smoothly with alcohol concentration. Experimental results are also presented for the growth rate of ice crystals in water–ethanol mixtures. For pure water, the measured crystal growth rate is 10.2 cm/s at 16 K supercooling. This is in excellent agreement with previous results from the literature. The crystal growth rate observed in ethanol–water mixtures however, can be orders of magnitude lower, where a mixture with 2% mole fraction ethanol has a growth rate of 2 mm/s. Further work is required to explain the large reduction in crystal growth rate with increasing alcohol concentration and to reproduce the behavior of the solid-formation temperatures with heterogeneous nucleation theory.publishedVersio