Solute-Solute Interactions in Jet Fuel by Ultralow Conductance Measurement

Solute-solute interactions in pure organic liquids are much easier to determine than solute-solute interactions in a complex organic mixture such as a middle distillate fuel. This paper presents a method for the determination of solute-solute interaction and infinite dilution diffusion coefficient of hydrogen bond donor-acceptor species using ultralow conductance measurement. A theoretical framework was developed to obtain both complexation equilibrium constant (K) and infinite dilution diffusion coefficient, D° from a single set of measurements. These equations were applied for the study in hexadecane, a model hydrocarbon, and in jet fuel. The D° for methanol in jet fuel, 1.38 × 10^-4 cm² s^-1, is indicative of hydrophobic environments for the polar solutes in hydrocarbons media. The conditional equilibrium constant, K', was found to be maximum for methanol in jet fuel, which indicates the presence of strong hydrogen bond acceptors in jet fuel. The present method is fairly general and applicable to polar and polarizable species in hydrocarbon media.