Study of Density and Viscosity of Formic Acid + 1-Alkanols Mixtures: Application of PC-SAFT Model

Abstract

In the present work, densities and viscosities for the formic acid (FA) + 1-Alkanol solutions have been analyzed. Excess molar volume $\mathop V\nolimits_{m}^{E}$ and viscosity deviation $\Delta \eta$ for five binary fluids of FA with 1-pentanol up to 1-nonanol at different temperatures were measured. Binary solutions of FA with 1-pentanol and 1-hexanol have negative $\mathop V\nolimits_{m}^{E}$, whereas other binary mixtures have positive $\mathop V\nolimits_{m}^{E}$. For the binary mixtures of FA and 1-nonanol, a miscibility gap was observed at the mole fractions greater than 0.78. All binary systems showed negative viscosity deviations. According to the findings, molecular interactions are stronger in the solutions containing shorter alcohols, and physical interactions are more important in longer 1-alkanols. The effects are related to the association between unlike molecules, dipolar interactions, and structural accommodations. Furthermore, the applicability of the PC-SAFT was tested to correlate the density, excess molar enthalpy, and the activity coefficients of the binary mixtures. Density and viscosity values are new and have not yet been reported in scientific papers.