Energetics of clouding and size effects in non-ionic surfactant mixtures: The influence of alkyl chain length and NaCl addition

Molina-Bolı́var, J.A.; Hierrezuelo, J. M.; Ruiz, C. Carnero

doi:10.1016/j.jct.2012.08.002

Cited by 26 publications

(21 citation statements)

References 51 publications

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“…The formation of clusters or aggregates of micelles at the cloud point is obviously guided by thermodynamic principles. At the phase separation temperature, the clouding components release their solvated water molecules and separate out from solution this can be considered as the limit of solubility [6][7][8]20,21]. As phase separation is a reversible process, the chemical potential of species should be equal between surfactant-rich and surfactant-poor phases.…”

Section: Thermodynamic Parameters At the Cloud Pointmentioning

confidence: 99%

“…As phase separation is a reversible process, the chemical potential of species should be equal between surfactant-rich and surfactant-poor phases. The standard Gibbs energy of phase separation (or clouding) 0 CP G  , can then be evaluated using the well-known equation [6][7][8]20,21]:…”

Section: Thermodynamic Parameters At the Cloud Pointmentioning

confidence: 99%

“…The negative values of T S  indicate that the association process overrides the dehydration step because the formation of larger aggregates involves the release of heat and increases the system's order [7,8]. Therefore, the driving force for the phase separation process is the tendency of dehydrated micelles to transfer from the solvent environment to a surfactant-rich phase.…”

Section: Thermodynamic Parameters At the Cloud Pointmentioning

confidence: 99%

“…Recent studies carried out in our laboratory [7,8] have demonstrated that it is possible to modulate the phase behavior of ethoxylated surfactants by mixing them with other non-ionic surfactants of a different nature. In particular, we are interested in carbohydrate-based surfactants, which are mainly characterized as having hydrophilic sugar headgroups in their polar moiety.…”

Section: Introductionmentioning

confidence: 99%

“…Separate studies with surfactants having the same nonpolar tail and varied polar headgroups as well as having the same headgroup with varying nonpolar tail in the presence and absence of additives are required to understand the involved physicochemical processes guiding the overall thermodynamics of clouding. In a previous publication we have studied the influence of the length of the hydrocarbon chain of sugar surfactants in phase separation of mixed micelles [8].…”

Section: Introductionmentioning

confidence: 99%

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An Energetic Analysis of the Phase Separation in Non-Ionic Surfactant Mixtures: The Role of the Headgroup Structure

Hierrezuelo

Molina-Bolı́var

Ruiz

2014

Entropy

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Abstract:The main goal of this paper was to examine the effect of the hydrophilic surfactant headgroup on the phase behavior of non-ionic surfactant mixtures. Four mixed systems composed of an ethoxylated plus sugar-based surfactants, each having the same hydrophobic tail, were investigated. We found that the hydrophilicity of the surfactant inhibits the tendency of the system to phase separate, which is sensitive to the presence of NaCl. Applying a classical phase separation thermodynamic model, the corresponding energy parameters were evaluated. In all cases, the parameters were found to depend on the type of nonionic surfactant, its concentration in the micellar solution and the presence of NaCl in the medium. The experimental results can be explained by assuming the phase separation process takes place as a result of reduced hydration of the surfactant headgroup caused by a temperature increase. The enthalpy-entropy compensation plot exhibits excellent linearity. We found that all the mixed surfactant systems coincided on the same straight line, the compensation temperature being lower in the presence of NaCl.

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Section: Thermodynamic Parameters At the Cloud Pointmentioning

confidence: 99%

Section: Thermodynamic Parameters At the Cloud Pointmentioning

confidence: 99%

Section: Thermodynamic Parameters At the Cloud Pointmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

An Energetic Analysis of the Phase Separation in Non-Ionic Surfactant Mixtures: The Role of the Headgroup Structure

Hierrezuelo

Molina-Bolı́var

Ruiz

2014

Entropy

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Extracting Membrane Proteins from Their Native Environment

Popot

2018

Membrane Proteins in Aqueous Solutions

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Sodium Alkyl Ether Sulfonates (SAES): Dual Anionic‐Nonionic Behavior in Synthetic Brine Having High Salinity and Hardness

Al-Faraji

Al-Maamari

Aoudia

2014

J Surfact & Detergents

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Due to the presence of non‐sulfonated residual alkyl ether (AE), sodium alkyl ether sulfonate (SAES) may exhibit clear point‐cloud point solubilization behavior in brine. Accordingly, the effect of temperature on the compatibility of iC17EOxS (x = 7 and 10), nC17EO10S, along with their analogous nonionic surfactants iC17EOxH (x = 7 and 10) and nC17EO10, in addition to iC9EO14 in brine has been investigated. Depending on their molecular structures, these surfactants exhibited concentration‐dependent clear point and cloud point solubilization behavior. The cloud point was associated with the AE component whereas the clear point was attributed to the sulfonated one. Interestingly, an increase in the cloud point of the nonionic component with respect to the corresponding nonionic AE (100 % active) was observed. Adding iC9EO14 (100 % active) to iC17EO7S (xan = 0.0–0.362) resulted in a significant decrease in the clear point of iC17EO7S from above 100 °C to below 22 °C with a concomitant increase in iC17EO7/iC9EO14 mixture cloud point from 68 °C. (xan = 0) to 72 °C (xan = 0.325). This relatively modest increase by 4 °C was attributed to the interrelationship of different competitive mechanisms, namely an increase in mixed micelle charge with increasing xan, the dehydration of OE groups via ion (SO3−)‐dipole (O → CH2) interactions, and possible shielding of SO3− groups by iC9EO14 nearby extended EO groups. To the best of our knowledge, this is the first instance where dual anionic‐nonionic solubilization behavior of SAES in brine characterized by high salinity and hardness is being reported.

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Energetics of clouding and size effects in non-ionic surfactant mixtures: The influence of alkyl chain length and NaCl addition

Cited by 26 publications

References 51 publications

An Energetic Analysis of the Phase Separation in Non-Ionic Surfactant Mixtures: The Role of the Headgroup Structure

An Energetic Analysis of the Phase Separation in Non-Ionic Surfactant Mixtures: The Role of the Headgroup Structure

Extracting Membrane Proteins from Their Native Environment

Sodium Alkyl Ether Sulfonates (SAES): Dual Anionic‐Nonionic Behavior in Synthetic Brine Having High Salinity and Hardness

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