Interaction of Some Amino Acids with Sodium Dodecyl Sulphate in Aqueous Solution at Different Temperatures

Abstract

The density ρ, and viscosity η of 0.00, 0.05, 0.10, 0.15, and 0.20 mol kg−1 glycine (Gly), dlalanine (Ala), dl-serine (Ser), and dl-valine (Val) have been measured in 0.002 mol kg−1 aqueous sodium dodecyl sulphate (SDS) at 298.15, 303.15, 308.15, and 313.15 K. These data have been used to calculate the apparent molar volume φv, infinite dilution apparent molar volume φv°, and the standard partial molar volumes of transfer φv° (tr), of the amino acids from water to the aqueous SDS solutions. Falkenhagen coefficient A, Jones-Dole coefficient B, free energies of activation per mole of solvent (aqueous SDS) Δμ1°*, and per mole solute (amino acids) Δμ2°*, also enthalpy ΔH* and entropy ΔS* of activation of viscous flow were evaluated using viscosity data. The molar refraction RD was calculated by using experimental values of the refractive index nD of the systems. The results have been interpreted in terms of ion-ion, ion-polar and hydrophobic-hydrophobic group interactions. The volume of the transfer data suggest that ion-ion intertactions are predominant.