Study of thermodynamic parameters of ternary solutions of polyethylene glycols in aqueous biotin solutions at multiple temperatures

The thermodynamic properties of polyethylene glycols (PEG 200 and PEG 400) within aqueous solutions of biotin that reveals crucial information concerning the intermolecular interactions developing in the liquid system. These assessments are made through analysing the volumetric-acoustic properties of the solutions that are determined using the density and speed of sounds values corresponding multiple temperatures which are reported in the current study. These experimental values for polyethylene glycols (PEG 200/PEG 400) are observed at constant 0.1 MPa atmospheric pressure in (0.0000, 0.0024, 0.0032, and 0.0040) mol.Kg(-1) and at different temperatures (288.15-318.15 K). Apparent molar properties (i.e., V-phi; K-phi,K-S), partial molar properties (i.e., V-phi(0); K-phi,S(0)), partial molar transfer properties (i.e., Delta V-phi(0); Delta K-phi,S(0)) and the partial molar expansibility (E-phi(0)) are calculated, which is accompanied by its first derivative (partial derivative E-phi(0)/partial derivative T)(P), from the obtained experimental density and speed of sound values. With these derived parameters the results are discussed which are interpreted as the nature of interactions occurring inside the mixture in accordance with the co-sphere overlap model. The pair and triplet interaction coefficients (i.e., V-AB, K-AB; V-ABB, K-ABB) are also evaluated in the present investigation using the partial molar properties. Also, for the ternary mixture of (biotin + water + PEGs) the hydration number (n(h)) is determined from compressibility data using Passynski's equation, where the findings are described in terms of cooperative hydrophobic interactions and hydration effects.