Calcium dodecyl sulfate precipitation from solutions containing sodium chloride

Gerbacia, William

doi:10.1016/0021-9797(83)90440-x

Cited by 16 publications

(8 citation statements)

References 12 publications

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“…To account for this, it is assumed that the mixture of Ca2+ and Na+ can be translated into an "equivalent" Na+ concentration. For any value of [Ca2+]un and [Na+]un, cmcDs can be calculated from eq [17][18][19][20]. There is a corresponding unbound Na+ concentration, [Na+]", that gives the same value of cmcDs in a NaDS + NaCl solution (without added divalent counterion).…”

Section: Resultsmentioning

confidence: 99%

Hardness tolerance of anionic surfactant solutions. 2. Effect of added nonionic surfactant

Stellner¹,

Scamehorn²

1989

Langmuir

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77fractional counterion binding of Na+ on a micelle electrical potential at the micelle surface, V W cohesive energy difference per molecule between the micellar and singly dispersed state, J/molecule zi valence of species i ocao fractional counterion binding of Ca2+ on a micelle Precipitation of anionic surfactant by calcium has been studied in the presence of added nonionic surfactant and added NaCl. A model is developed that can predict the precipitation boundary as a function of surfactant composition and concentration of added NaCl. The model uses a solubility product relationship between anionic surfactant monomer and unbound calcium and a regular solution theory description of monomer-micelle equilibrium and considers counterion binding of divalent and monovalent counterions onto the micelles. The model works well at moderate NaCl concentrations but is less accurate at high NaCl concentrations. Calculatiom from the model c o n f i i that mixed micelle formation is responsible for increased hardness tolerance in anionic surfactant solutions when nonionic surfactant is added.

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Section: Resultsmentioning

confidence: 99%

Hardness tolerance of anionic surfactant solutions. 2. Effect of added nonionic surfactant

Stellner¹,

Scamehorn²

1989

Langmuir

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“…Gerbacia (26) observed that addition of nonionic surfactants increases the hardness tolerance of solutions of anionic surfactants. Nishikido et al (27) showed that the Krafft temperature of solutions of anionic and nonionic surfactants was lower than that of solutions of anionic surfactant only.…”

Section: Resultsmentioning

confidence: 99%

Surfactant precipitation in aqueous solutions containing mixtures of anionic and nonionic surfactants

Stellner

Scamehorn

1986

J Americ Oil Chem Soc

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The salinity tolerance (precipitation phase boundary) is measured for a mixed anionic/nonionic surfactant system above the CMC. For any total surfactant concentration, the salinity tolerance is shown to increase as the percentage of nonionic surfactant in the system is increased. A model is developed which can predict the phase boundaries for the mixed surfactant system from the pure anionic surfactant phase boundary and information about mixed micelle formation. In the model, precipitation is viewed as a solubility product relationship between the anionic surfactant monomer and the total unassociated counterion. The reason that salinity tolerance (or counterion concentration necessary to cause precipitation) increases with addition of nonionic surfactant is that mixed micelle formation reduces the anionic surfactant monomer concentration. For the experimental studies, sodium dodecyl sulfate is the anionic surfactant, a polyethoxylated nonylphenol is the nonionic surfactant, and sodium chloride is the added salt.

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“…Surfactant Solubility. Investigations of the effect of divalent ions on dodecyl sulfate surface aggregates are limited by the precipitation of the hydrated divalent surfactant salt in a large region of the bulk solution phase diagram. , The low Krafft temperature of Mn(DS) 2 enabled us to measure the surface aggregate structure over a broad range of Mn 2+ concentration (up to 0.44 M) in 1 mM SDS and to achieve a high ratio of divalent to monovalent ions. The Krafft temperatures of Ca(DS) 2 and Mg(DS) 2 are above room temperature, so the range of accessible concentrations is more restricted in these cases.…”

Section: Methodsmentioning

confidence: 99%

Weak Influence of Divalent Ions on Anionic Surfactant Surface-Aggregation

1997

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The aggregated structure of sodium dodecyl sulfate (SDS) adsorbed to the graphite−solution interface has been determined in the presence of the divalent ions: Mg2+, Mn2+, and Ca2+. Divalent ions are expected to alter the electrostatic interactions between charged headgroups and thus to cause changes from the structure formed with monovalent ions. However, atomic force microscopy reveals that the adsorbed structures are long (μm) and thin (∼5 nm) and thus very similar in appearance to those observed in the presence of only monovalent counterions. Energetic considerations suggest that under most conditions the aggregates are hemicylinders, although not necessarily of constant curvature. When Mn2+ is added at constant low SDS concentration, the narrow dimension of the structure (the period) decreases linearly with solution Debye length down to a limiting period of about 5 nm. When Mg2+ is added at constant low SDS concentration, the period decreases slightly and then remains roughly constant. This suggests that the aggregate diameter increases. For both of these ions, force measurements suggests that there is a transition from a thin layer to a thicker layer as the divalent ion is added. At surfactant concentrations several times greater than the critical micelle concentration, the addition of divalent ions has no observable effect on the adsorption. We did not observe a transition to a flat layer at any of the conditions examined.

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Calcium dodecyl sulfate precipitation from solutions containing sodium chloride

Cited by 16 publications

References 12 publications

Hardness tolerance of anionic surfactant solutions. 2. Effect of added nonionic surfactant

Hardness tolerance of anionic surfactant solutions. 2. Effect of added nonionic surfactant

Surfactant precipitation in aqueous solutions containing mixtures of anionic and nonionic surfactants

Weak Influence of Divalent Ions on Anionic Surfactant Surface-Aggregation

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