Abstract

Roksana Khatun¹ and Md. Nazrul Islam²

The volumetric studies on the binary aqueous solutions of sodium dodecyl sulphate (SDS) and ternary SDS-amino acid-water systems have been carried out as a function of concentration and at 15, 20 , 25 , 30 , 35 , 40 , 45 and 50 °C. In this study the variation of apparent molar volume (fn) of SDS was observed in the low concentration region. The limiting apparent molar volume (f0n) values of SDS in aqueous amino acid solutions are greater than those in water and increase with the concentration at all the studied temperatures. The greater f0n value in amino acid solution has been demonstrated strong ion-ion interactions in the ternary system. Apparent molar expansions (FE) in aqueous solution and ternary SDS-amino acid-water systems are very sensitive to hydrophobic and hydrophilic solute-solute interactions.  Expansibility, a and apparent molar expansion, FE  reflect from the same structural alteration in the solutions. In our investigation, critical micelle concentration (c.m.c) of SDS at various SDS-amino acid-water systems  also determined by apparent molar volume (fn). Among various physical parameters, apparent molar volume, limiting apparent molar volume, Apparent molar expansion  has been recognized as a quantity that is sensitive to structural changes occurring in solutions.

Sodium dodecyl sulphate; glycine; alanine; apparent molar volume

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