Modeling and Experimental Characterization of Undecane and 2-Alkanol Interactions

This study experimentally investigates the intermolecular forces governing n-undecane +2-alkanol (C₃–C₇) at varying temperatures using density and viscosity measurements. Excess molar volumes (V^E) and viscosity deviations (Δη) were calculated to characterize the mixing behavior. Positive V^E values suggest that n-undecane disrupts the hydrogen bonding network within the 2-alkanols, leading to volumetric expansion. The trend of decreasing V^E with increasing alkanol chain length indicates improved molecular packing. Negative Δη values suggest a reduction in viscosity compared to ideal mixing, with longer alkanols exhibiting more negative deviations, implying a greater disruption of cohesive forces. The PC-SAFT equation of state was used to correlate the mixture densities, yielding results in excellent accord with the experimental data by optimizing the adjustable parameters (k_ij), as confirmed by small absolute average deviations. The highest observed deviation between experimental and predicted densities was 0.64%, which was found in the undecane +2-heptanol mixture. The results offer valuable insights into the thermodynamic properties of alkane–alcohol mixtures, with implications for fuel formulation and chemical process engineering.