Abstract: Densities of L-serine-n-propanol-water ternary solutions have been measured at 298.15 K by an oscillating-tube densimeter. Apparent molar volumes, limiting partial molar volumes, transfer partial molar volumes and hydration numbers for L-serine have been calculated. The transfer volumes from water to n-propanol-water mixtures and hydration numbers have been discussed in terms of the structural hydration interaction model. The results show that a dominant interaction between —OH group of n-propanol and the zwitterionic group of serine gives positive contribution to the transfer volume. The transfer volumes of serine from water to n-propanol-water mixed solvents are positive, and increase with increasing n-propanol concentration, while the hydration numbers decrease with increasing n-propanol concentration.

Key words: L-serine, n-propanol, Limiting partial molar volumes, Structural interactions