Investigating the thermophysical properties of the 1-Butanol + Biodiesel System: The impact of pressure on volumetric characteristics.

• Density measurements were conducted for the mixture of 1-butanol and two biodiesels under high-pressure conditions (up to 100 MPa). • Excess volumes were calculated for the blend of 1-butanol + biodiesel. • Correlation with the Tammann-Tait equation was performed, and derived properties were calculated. • Thermodynamic modeling was carried out using the PC-SAFT equation of state. Biodiesel, derived from renewable sources, offers advantages like biodegradability and compatibility with diesel engines. However, high production costs and low-temperature viscosity issues must be addressed. This could be mitigated by blending biodiesel with medium-chain alcohols. This study aims to assess the volumetric properties of the 1-butanol + biodiesel system under high-pressure conditions (0.1 – 100 MPa) and various temperatures (293.15 – 373.15 K) using a DMA HPM device from Anton Paar. Integrating experimental and modeling approaches, we applied equations to obtain derived properties and correlate density data. Equations such as Tammann-Tait and PC-SAFT were applied to the experimental data, yielding maximum mean absolute percentage deviations (DMRA Max.) of 0.011 % and 0.439 %, respectively, indicating satisfactory fits to the experimental data. The excess volumes were calculated, revealing minimal deviation from ideal behavior, with a maximum deviation of 0.15 % of the total volume. This suggests that the volumetric behavior of the 1-butanol + methyl biodiesel system closely resembles that of an ideal solution. We used both equations to obtain derived properties, such as the compressibility (κ T) and the isobaric thermal expansivity (α P). It was observed that the PC-SAFT equation has some limitations in its prediction. From these results, a crossing point in isobaric thermal expansivity (α P) was observed; this could be attributed to increasing biodiesel content, potentially linked to the effects of intermolecular forces. [ABSTRACT FROM AUTHOR]