Role of alkanols in micellar growth: A viscometric study

Kumar, Sanjeev; Kirti,; Kumari, Krishna; Kabir-ud-Din, †

doi:10.1007/bf02541031

Cited by 10 publications

(12 citation statements)

References 23 publications

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“…Self association of surfactant molecules into spherical micelles becomes apparent around the critical micelle concentration (cmc) . The spherical micelles show unidimensional (the so-called rod-shaped micelles) growth in certain systems on increasing the surfactant concentration and/or depending upon appropriate conditions of salinity, temperature, and presence of suitable additives (salt, − alcohol, − amine, ,− or hydrocarbon 21,32-38 ). Here micellar growth is achieved by forming rodlike micelles of increasing length.…”

Section: Introductionmentioning

confidence: 99%

Micellar Growth in the Presence of Salts and Aromatic Hydrocarbons: Influence of the Nature of the Salt

1999

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Viscosity measurements under Newtonian flow conditions have been performed at 40 °C to study the effect of aromatic hydrocarbons (benzene, toluene, or o-xylene) on aqueous micellar solutions of 0.1 M cetylpyridinium bromide (CPB) containing different salts. Two series of salts, viz. (i) inorganic (KX; X ) Cl, Br, or NO3) and (ii) symmetrical quaternary ammonium (R4NBr; R ) H, CH3, C2H5, n-C3H7, or n-C4H9), were used to explore the effect of their nature and concentration. The hydrocarbons had marginal effect on viscosity when added to CPB solutions having no salt. However, in the presence of salts, the viscosity behavior was quite different (synergistic effect). Relative viscosity (ηr) versus concentration of hydrocarbon plots were constructed for various fixed salt concentrations. Most of the time, after reaching a maximum value, ηr decreased on further addition of hydrocarbons, showing a peaked behavior. The peak position (maximum) as well as the viscosity at the maximum, ηr max , was found to be dependent on the nature/ concentration of salts, hydrocarbons, and counterions. However, the viscosity behavior was different with the R4N salts having a longer alkyl (R) part (the synergism progressively diminished). The effect of concentration of salt was reversed and peaked behavior was also lost. This reversal and change in behavior have been explained in terms of the salting-in nature of these salts as compared to the salting-out nature of the salts of series i.

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Section: Introductionmentioning

confidence: 99%

Micellar Growth in the Presence of Salts and Aromatic Hydrocarbons: Influence of the Nature of the Salt

1999

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“…We are engaged in a systematic study of effects of addition of salts and organic molecules singly/jointly on micellar growth in aqueous ionic surfactant solutions. − Our investigations have primarily been concerned with how viscosity measurements can be used to study the micellar growth/shape transition and how the combined presence of salt−organics influences the viscosity and overall organization of surfactant molecules.…”

Section: Introductionmentioning

confidence: 99%

Synergistic Effect of Salts and Organic Additives on the Micellar Association of Cetylpyridinium Chloride

1997

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Viscosity measurements under Newtonian flow conditions have been made to study the effect of organic additives on the micellar association of 0.2 M cetylpyridinium chloride (CPC) in aqueous medium at 30°C containing different fixed concentrations of potassium salts (mainly KCl). 1-Hexanol (C6OH) and n-heptylamine (C7NH2) were used as the organic additives, and relative viscosity (ηr) vs [additive] plots were constructed for various KCl concentrations (0-2 M). In each case, after reaching a maximum, the |ηr| decreased on further addition of the additive (i.e., a peaked behavior). An interesting phenomenon of progressive shifting of the peak position toward lower [additive] was observed with increase in KCl concentration. This peak shift was found to be dependent on nature of the counterion but almost independent on the co-ion nature. The start of viscosity decrease at lower [additive] may be due to the fact that in the presence of KCl (because of its salting-out nature), the palisade layer gets saturated earlier and the excess content begins to solubilize inside the micellar coresthe evidence to this effect is provided by performing identical experiments with n-hexane and n-octane. Availability of the additive in the micellar interior could provided more flexibility as well as swelling (of higher degree of sphericity), which forms the basis of viscosity decrease. For a constant CPC content, a well-defined linear relationship was found to exist between [KCl] and [additive] at the viscosity maximum (η r max ); these results could be helpful to tune viscosities of surfactant formulations.

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“…Surfactants with smaller a tend to form larger, less curved, or even inverted aggregates. For ionic surfactants, the area shrinking effect may be obtained by salt (with common counter-ion) addition (13,14) or organic compound solubilization (6,7,(15)(16)(17).…”

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“…More studies are needed to increase understanding of the effect of hydrocarbons on the properties of micellar systems and micellar growth. In the last few years, the authors have reported micellar growth processes in the presence of various alcohols and amines (7,(15)(16)(17). These reports have shown how these compounds can be used to vary the area per ionic group (a), a parameter of overriding importance for such growth processes.…”

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Effects of various hydrocarbons on micellar growth

Kumar

David

Kabir-ud-Din

1997

J Americ Oil Chem Soc

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The effect of aliphatic and aromatic hydrocarbons on surfactant micellar growth has been investigated by viscosity measurements at 40°C. Aqueous and aqueous KBr (0.1 M) solutions of 0.1 M cetylpyridinium bromide (CPB) showed that the viscosity behavior changed substantially in the presence of KBr. This is attributed to favorable conditions produced by KBr that assist micellar growth by addition of hydrocarbons. Reasons for the effectiveness of the solubilized hydrocarbons are suggested and supported by theoretical arguments. The causes of viscosity decrease at higher aromatic hydrocarbon concentrations are also explained. Micellar growth with soluble aromatic/aliphatic hydrocarbons could also be initiated if a moderate salt concentration is present in CPB micellar solutions. The chainlength, solubilization site, and molar volume of the soluble hydrocarbons all affect the bulk viscosity of the solution. Such surfactant and hydrocarbon combinations may find use in micellar-enhanced ultrafiltration of benzene and its derivatives, but it should be kept in mind that micellar shape may change and be more curved at higher benzene derivative concentrations. JAOCS 74, 797-801 (1997).

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Role of alkanols in micellar growth: A viscometric study

Cited by 10 publications

References 23 publications

Micellar Growth in the Presence of Salts and Aromatic Hydrocarbons: Influence of the Nature of the Salt

Micellar Growth in the Presence of Salts and Aromatic Hydrocarbons: Influence of the Nature of the Salt

Synergistic Effect of Salts and Organic Additives on the Micellar Association of Cetylpyridinium Chloride

Effects of various hydrocarbons on micellar growth

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