Excess Thermodynamic and Transport Investigations for the Binary Mixtures of 1,2,3,4-Tetrahydronaphthalene with Fatty Acid Ethyl Esters as Potential Biodiesel Fuels

Experimental investigations of thermophysical properties such as density (rho), viscosity (eta), speed of sound (u), and refractive index (n(D)) have been carried out for the binary systems of 1,2,3,4-tetrahydronaphthalene (tetralin) with ethyl caprate (EC), ethyl laurate (EL), and ethyl myristate (EM) at temperatures of 293.15-323.15 K and pressure of 0.1 MPa. These measured properties have been employed to calculate various derived parameters such as excess molar volume (V-m(E)), deviation in isentropic compressibility (Delta kappa(s)), viscosity deviation (Delta eta), excess Gibbs free energy of activation of viscous flow (Delta G*(E)), and deviation in refractive index (Delta n(D)). Further, these parameters have been correlated, employing the Redlich Kister equation. In general, V-m(E) values are negative while Delta kappa(s) values are positive over the entire composition range of binary mixtures. Compared to the tetralin + EM system, an easy flow of tetralin + EC and tetralin + EL binary mixtures has been ascertained by their negative Delta eta values. The sign and magnitude of different derived parameters have been used to interpret the existence of specific interactions as well as structural effects within the investigated binary mixtures. Such results could contribute toward the development and designing of bio-based diesel fuels.