Thermodynamic properties of rhamnolipid micellization and adsorption

Mańko, Diana; Zdziennicka, Anna; Jańczuk, Bronisław

doi:10.1016/j.colsurfb.2014.04.020

Cited by 67 publications

(92 citation statements)

References 50 publications

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“…However, the maximal Gibbs surface excess concentration of SDS is practically constant in the range of RL concentration corresponding to the unsaturated monolayer at the water–air interface of individual RL (Fig. 3a) [19]. On the other hand, the same relation is observed for RL (Fig.…”

Section: Methodsmentioning

confidence: 69%

“…The ratio of the number of water molecules contacted with RL and SDS molecules is equal to 1.67. The Gibbs standard free energy of mono-rhamnolipid adsorption calculated from the Langmuir equation is equal to −85.04 kJ/mol [19] and SDS −52.1 kJ/mol [20]. The ratio of free energies is equal to 1.63.…”

Section: Methodsmentioning

confidence: 99%

“…The “real” sum was obtained from the data presented in Fig. 3a, b and the “hypothetical” one on the basis of surface excess concentration of individual surfactants [19, 20]. In the case of “real” isotherm Γ SDS + Γ RL increases from (line 5) to a maximum at the concentration being close to the first one corresponding to the saturated monolayer of RL in the absence of SDS [19].…”

Section: Methodsmentioning

confidence: 99%

“…3a, b and the “hypothetical” one on the basis of surface excess concentration of individual surfactants [19, 20]. In the case of “real” isotherm Γ SDS + Γ RL increases from (line 5) to a maximum at the concentration being close to the first one corresponding to the saturated monolayer of RL in the absence of SDS [19]. This maximum is lower than that of ( is a limiting Gibbs surface excess concentration of SDS in the absence of RL at the water–air interface) [20].…”

Section: Methodsmentioning

confidence: 99%

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Adsorption and Aggregation Activity of Sodium Dodecyl Sulfate and Rhamnolipid Mixture

Mańko

Zdziennicka

Jańczuk

2016

J Surfact & Detergents

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Measurements of the surface tension, density and viscosity of sodium dodecyl sulfate (SDS) and rhamnolipid (RL) mixtures were carried out in aqueous solution. From the obtained results, composition of mixed surface layer at the water–air interface, mixed micelles, parameter of intermolecular interactions, activity of SDS and RL in the surface layer and micelles, Gibbs standard free energy of adsorption and micellization as well as Gibbs free energy of SDS and RL mixing in the surface layer and micelles were established. These parameters were discussed in the light of independent adsorption of SDS and RL and the size of their molecules as well as the area in contact with water molecules. A correlation between the number of water molecules in contact with those of SDS and RL and standard free energy of adsorption as well as micellization of these surfactants was observed. A correlation between the apparent and partial molar volumes of RL and SDS in their mixture and size of surfactant molecules as well as the average distance between molecules was also found. The parameter of intermolecular interactions indicates that there is a synergetic effect in the reduction of water surface tension and micelle formation.Electronic supplementary materialThe online version of this article (doi:10.1007/s11743-016-1916-6) contains supplementary material, which is available to authorized users.

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Section: Methodsmentioning

confidence: 69%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Adsorption and Aggregation Activity of Sodium Dodecyl Sulfate and Rhamnolipid Mixture

Mańko

Zdziennicka

Jańczuk

2016

J Surfact & Detergents

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“…10,14,16,17,20 Thus, a need still exists to fully characterize the aggregation properties of these surfactants in solution as well as to probe the chemical microenvironments within these aggregates, especially at concentrations below ~20 mM. Toward this end, we report the combined use of surface tensiometry, fluorescence spectroscopy, 21,22 fluorescence quenching, 23,24 and DLS combined with all-atom molecular dynamics (MD) simulations to better understand the aggregation properties of anionic monorhamnolipids in aqueous solution at basic pH.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Aggregate Structure in Solutions of Anionic Monorhamnolipids: Experimental and Computational Results

et al. 2017

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The evolution of solution aggregates of the anionic form of the native monorhamnolipid (mRL) mixture produced by Pseudomonas aeruginosa ATCC 9027 is explored at pH 8.0 using both experimental and computational approaches. Experiments utilizing surface tension measurements, dynamic light scattering, and both steady-state and time-resolved fluorescence spectroscopy reveal solution aggregation properties. All-atom molecular dynamics simulations on self-assemblies of the most abundant monorhamnolipid molecule, L-rhamnosyl-β-hydroxydecanoyl-β-hydroxydecanoate (Rha-C10-C10), in its anionic state explore the formation of aggregates and the role of hydrogen bonding, substantiating the experimental results. At pH 8.0, at concentrations above the critical aggregation concentration of 201 μM but below ~7.5 mM, small premicelles exist in solution; above ~7.5 mM, micelles with hydrodynamic radii of ~2.5 nm dominate, although two discrete populations of larger lamellar aggregates (hydrodynamic radii of ~10 and 90 nm) are also present in solution in much smaller number densities. The critical aggregation number for the micelles is determined to be ~26 monomers/micelle using fluorescence quenching measurements, with micelles gradually increasing in size with monorhamnolipid concentration. Molecular dynamics simulations on systems with between 10 and 100 molecules of Rha-C10-C10 indicate the presence of stable premicelles of seven monomers with the most prevalent micelle being ~25 monomers and relatively spherical. A range of slightly larger micelles of comparable stability can also exist that become increasing elliptical with increasing monomer number. Intermolecular hydrogen bonding is shown to play a significant role in stabilization of these aggregates. In total, the computational results are in excellent agreement with the experimental results.

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Characterization of a biosurfactant produced by Peruvian strain Pseudomonas aeruginosa 6K‐11

Obregon‐Maldonado,

Merino‐Rafael,

Gutiérrez‐Moreno

2024

J of Chemical Tech & Biotech

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BACKGROUNDThe oil industry has a big impact on the environment by itself and by using chemically synthesized surfactants. Biosurfactants are an ecofriendly alternative, especially rhamnolipids produced by Pseudomonas aeruginosa. Rhamnolipids in a determined concentration decrease the liquid surface tension, and this allows access oil hydrocarbon to be degraded. The objective of this research is to characterize the biosurfactant produced by the native strain P. aeruginosa 6K‐11 by determining its critical micelle concentration (CMC), Krafft point, and emulsifying activity.RESULTSExperiments were initially performed with rhamnolipid produced by P. aeruginosa 6K‐11 growing on Siegmund‐Wagner medium with 1% of waste oil as carbon source and at 31.26 °C, 186 rpm after 42 h of incubation. After that, the biosurfactant was purified according to acid precipitation methodology. The first conductivity measurement, 34 μS/cm, was obtained with 12.5 g/L of rhamnolipid by using an APERA conductivity meter. The rhamnolipid CMC was 5.86 g/L due to the conductivity measurements graph and 0.49 was the dissociation degree. The equations of both lines were found by the method of least squares. The rhamnolipid has produced 1.97 Units of Emulsifying Activity (UEA) and 50% stability was observed based on the E24 Index. The highest conductivity achieved under 39 °C, as calculated from a conductivity against temperature graph, was the Krafft point.CONCLUSIONThese findings give important parameters to characterize the P. aeruginosa 6K‐11 biosurfactant activity that can be used to accelerate oil biodegradation in bioremediation processes. © 2024 Society of Chemical Industry (SCI).

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Thermodynamic properties of rhamnolipid micellization and adsorption

Cited by 67 publications

References 50 publications

Adsorption and Aggregation Activity of Sodium Dodecyl Sulfate and Rhamnolipid Mixture

Adsorption and Aggregation Activity of Sodium Dodecyl Sulfate and Rhamnolipid Mixture

Evolution of Aggregate Structure in Solutions of Anionic Monorhamnolipids: Experimental and Computational Results

Characterization of a biosurfactant produced by Peruvian strain Pseudomonas aeruginosa 6K‐11

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