TY - JOUR
T1 - Sodium lauryl ether sulfate micellization and water solubility enhancement towards naphthalene and pyrene
T2 - Effect of the degree of ethoxylation
AU - Aoudia, Mohamed
AU - Al-Haddabi, Butheina
AU - Al-Harthi, Zuleikha
AU - Al-Rubkhi, Aadel
N1 - Funding Information:
Acknowledgments We are very grateful for His Majesty Sultan Qaboos for the financial support of this work (Grant: SR/SCI/CHE/ 04/01).
PY - 2010/1
Y1 - 2010/1
N2 - The effect of ethoxylation on self-aggregation behavior in aqueous media of sodium lauryl ether sulfate (SLES), C12H25 (OCH 2CH2)xOSO3Na, where x = 1 (SLE1S), x = 2 (SLE2S), and x = (SLE3S) was investigated. CMCs were determined from the effect of surfactant concentration on (2,2' -bipyridine dichlororuthenium(II) hexahydrate (Ru(bipy)32+ ,2Cl- ) fluorescence emission. Aggregation numbers and micelle concentrations were estimated from the fluorescent quenching of (Ru(bipy)32+,2Cl-) by 9-methylanthracene. Interestingly, critical micelle concentrations (0.80 μM), average aggregation numbers (N = 43), and micelle concentrations ([M] = 40 lM) were found to be independent of the degree of ethoxylation. Water solubilization enhancement of naphthalene and pyrene by SLES was also investigated. Water solubility enhancement for naphthalene and pyrene was observed with increasing degrees of ethoxylation and follow the order SLE3S > SLE2S > SLE1S. The higher impact of oxyethylene (OE) groups on solubilization enhancement of naphthalene over pyrene was taken as an indication for a preferential distribution of the relatively polar organic naphthalene molecule at the outer layer of the micelle in close contact with the hydrated oxyethylene units, thereby allowing for a strong polycyclic aromatic hydrocarbon (PAH) - micelle interaction. On the other hand, pyrene molecule is preferentially distributed in the core of the micelle, relatively far away from the OE units located at the micelle-water interface for PAH-micelle interaction to occur. Water solubility enhancement for both PAHs was also was associated with an increase in SLES micelle size with the degree of ethoxylation as well as to the accessibility of the locus solubilization for the solute.
AB - The effect of ethoxylation on self-aggregation behavior in aqueous media of sodium lauryl ether sulfate (SLES), C12H25 (OCH 2CH2)xOSO3Na, where x = 1 (SLE1S), x = 2 (SLE2S), and x = (SLE3S) was investigated. CMCs were determined from the effect of surfactant concentration on (2,2' -bipyridine dichlororuthenium(II) hexahydrate (Ru(bipy)32+ ,2Cl- ) fluorescence emission. Aggregation numbers and micelle concentrations were estimated from the fluorescent quenching of (Ru(bipy)32+,2Cl-) by 9-methylanthracene. Interestingly, critical micelle concentrations (0.80 μM), average aggregation numbers (N = 43), and micelle concentrations ([M] = 40 lM) were found to be independent of the degree of ethoxylation. Water solubilization enhancement of naphthalene and pyrene by SLES was also investigated. Water solubility enhancement for naphthalene and pyrene was observed with increasing degrees of ethoxylation and follow the order SLE3S > SLE2S > SLE1S. The higher impact of oxyethylene (OE) groups on solubilization enhancement of naphthalene over pyrene was taken as an indication for a preferential distribution of the relatively polar organic naphthalene molecule at the outer layer of the micelle in close contact with the hydrated oxyethylene units, thereby allowing for a strong polycyclic aromatic hydrocarbon (PAH) - micelle interaction. On the other hand, pyrene molecule is preferentially distributed in the core of the micelle, relatively far away from the OE units located at the micelle-water interface for PAH-micelle interaction to occur. Water solubility enhancement for both PAHs was also was associated with an increase in SLES micelle size with the degree of ethoxylation as well as to the accessibility of the locus solubilization for the solute.
KW - Aggregation number
KW - Degree of ethoxylation
KW - Fluorescence quenching
KW - Micelle
KW - Solubilization
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U2 - 10.1007/s11743-009-1131-9
DO - 10.1007/s11743-009-1131-9
M3 - Article
AN - SCOPUS:77949425329
SN - 1097-3958
VL - 13
SP - 103
EP - 111
JO - Journal of Surfactants and Detergents
JF - Journal of Surfactants and Detergents
IS - 1
ER -