Effect of temperature on the surface properties of α,ω-amino acids in dilute aqueous solutions

Abstract

In this work, experimental results for surface tension of aqueous solutions of 3-aminopropanoic acid, 4-aminobutanoic acid, 5-aminopentanoic acid and 6-aminohexanoic acid at T = (293.15, 298.15, 303.15 and 308.15) K at several concentrations are presented. The results were used to evaluate the limiting experimental slopes of surface tension with respect to mole fraction at each temperature. Surface tension measurements were taken using a LAUDA TVT-2 drop volume tensiometer with temperature control better than 0.1 K at T = (293.15, 298.15, 303.15 and 308.15) K The thermodynamic behavior of the aqueous α,ω-amino acid solutions is compared with that reported for α-amino acids in water. The surface behavior is discussed in terms of the effect of the hydrocarbon chain and the position of polar groups on water structure. The temperature dependence of the limiting slopes of surface tension with respect to mole fraction, derived from surface tension measurements, is discussed.