Apparent molar volumes and isentropic compressibilities of transfer of L-alanine from water to aqueous potassium di-hydrogen citrate and tri-potassium citrate at T = (283.15 to 308.15) K

The apparent molar volumes and isentropic compressibilities of L-alanine have been obtained in water, in aqueous solutions of 0.18, 0.50 and 1.00 mol kg(-1) potassium di-hydrogen citrate (KH(2)Cit) and in aqueous solutions of 0.14, 0.50 and 1.00 mol kg(-1) tri-potassium citrate (K(3)Cit) at T=(283,15, 288.15, 293.15, 298.15, 303.15 and 308.15) K at atmospheric pressure from measurements of density and ultrasonic velocity. The infinite dilution apparent molar volume and isentropic compressibility values of alanine have been obtained and from which the infinite dilution apparent molar volumes and isentropic compressibilities of transfer of L-alanine from water to aqueous potassium di-hydrogen citrate and tri-potassium citrate solutions have been obtained for the investigated salt concentrations and temperatures. It was found that, the apparent molar isentropic compressibility of alanine in both KH(2)Cit and K(3)Cit aqueous solutions is negative and increases by increasing temperatures and salt concentrations. Also, the results show that the apparent molar volume of alanine increases by increasing salt concentrations and temperatures. (C) 2008 Elsevier B.V. All rights reserved.