Volumetric and viscometric studies on dodecyltrimethylammonium bromide in aqueous and in aqueous amino acid solutions in premicellar region

摘要

The densities and viscosities of dodecyltrimethylammonium bromide (DTAB), glycine, and rac-alanine in water and DTAB in glycine/alanine aqueous solutions have been determined at 288.15, 296.15, 304.15, 312.15, and 320.15 K. The apparent molar volumes (φ_v) were obtained from these density data. The limiting apparent molar volumes (φ_v~0) and experimental slopes (S_v) were derived from the Masson equation and interpreted in terms of solute-solute and solute-solvent interactions. The sign of [δ~2(φ_v~0)/δT~2]_p, which corresponds to structure-making or structure-breaking properties of solutes, was determined. The viscosity coefficients A, B, and D were obtained from viscosity data on the basis of the Jones-Dole equation. Glycine/alanine in aqueous solutions exhibit structure-breaking behavior. In premicellar region, DTAB in aqueous solutions exhibits structure-breaking behavior, and DTAB in aqueous glycine/alanine solutions exhibits structure-making behavior. The free energy, enthalpy, and entropy of activation were calculated using the Nightingale and Benck, and Eyring equations. The values of (Δμ1~# - Δμ_0~#) for solutions were calculated. The effects of solutes on the structure of water were interpreted in terms of viscosities and the thermodynamic parameters.