Influence of Phosphate-Based Salts on Enthalpy of Dilution and Isentropic Compressibility Properties of Saccharides and Their Derivatives in Aqueous Solutions

The standard enthalpies of dilution (Delta H-dil degrees) and isentropic compressibilities (K-s,K-2 degrees) of some saccharides and their derivatives; (-)-D-ribose, (+)-D-glucose, 2-deoxy-D-glucose, (+)-methyl alpha-D-glucopyranoside, (+)-maltose monohydrate, and (+)-raffinose pentahydrate (solutes) were determined from heat change (q) and speed of sound (u) data measured, respectively, in (0.05, 0.15, 0.25, and 0.35) mol.kg(-1) and (0.5, 1.0, 1.5 and 2.0) mol.kg(-1) aqueous solutions of sodium phosphate (NaH2PO4), ammonium phosphate (NH4H2PO4) monobasic salts, and potassium phosphate (K3PO4) tribasic salt at T = 288.15-318.15 K at P = 0.1 MPa. Other parameters such as transfer values (Delta(t)(Delta H-dil degrees), Delta K-t(s,2)degrees), change in heat capacity (Delta C-dil(p,2,m)degrees), and hydration numbers (n(w)) were also derived to rationalize the molecular interactions in mixtures of saccharide and derivative and phosphate-based salts. These studies are important to understand various interactions in terms of changing cation (Na+, NH4+, and K+) and anion (H2PO4- and PO43-) size, ionic strength, and influence of salts on water structure.