IJSTR >> Volume 5 - Issue 8, August 2016 Edition

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AUTHOR(S)

Alzahraa A. El Feky,‎ Magda N. Shalaby, Omnia A.A. El-Shamy, Suzy A. ‎Selim

KEYWORDS

Surface activity, Surface excess concentration, minimum ‎surface area per molecule, surface tension, surfactants.‎

ABSTRACT

The adsorption of a series of ethoxylated nonionic and anionic ‎surfactant molecules at aqueous / air interface at different temperature ‎ranges [298, 308, 318, 328 and 338K] was studied. Different surface ‎parameters were evaluated from surface tension measurements at ‎different temperatures. The effectiveness of adsorption, Гmax, for all ‎nonionic and anionic surfactants was discussed with respect to their ‎hydrophilic and hydrophobic characters. Ethoxylated stearate had the ‎lowest effectiveness of adsorption at 298K comparing to other ‎nonioics. Minimum surface area per molecule, Amin, was calculated ‎which provides information on the degree of packing and orientation ‎of the adsorbed surfactant molecules. Amin decreased through ‎increasing the hydrophobicity. Also, the effectiveness of surface ‎tension reduction, πcmc was discussed concerning on surfactant ‎structures. The dependence of surface parameters (Гmax and Amin) on ‎temperatures was explained in details. For the most investigated ‎nonionic and anionic surfactants πcmc were slightly affected by ‎temperature.‎

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