Thermodynamic study on the prevention of B30 biodiesel wax crystallization by γ-Al2O3 nanoparticles and sorbitan monooleate.

[Display omitted] • Needle-like γ-Al 2 O 3 nanoparticles and SMO was successfully used as CFI additives. • The addition of γ -Al 2 O 3 nanoparticles and SMO reduces of crystallization temperature. • CFI additives were able to prohibit thermodynamic spontaneity of wax crystallization. • DLVO analysis showed that γ -Al 2 O 3 nanoparticles had high colloidal stability in fuel. • CFI additives were able to suppress the insoluble paraffinic "house of cards" crystals. This paper reports a thermodynamic investigation on the role of γ-Al 2 O 3 nanoparticles and sorbitan monooleate (SMO) as cold-flow improver additives for B30 biodiesel blend. Here, the two additives were able to improve fuel's cold-flow properties and responsible for reducing wax crystallization temperature as low as 6.42 °C. Based on DCS analysis, the addition of individual SMO or γ-Al 2 O 3 nanoparticles gave rise to the increase in crystallization enthalpy and entropy. However, the opposite effect was observed when they were used in combination. This synergistic effect was found to be responsible for making them effective in the prohibiting the spontaneity of wax crystallization, which was proven by the increase in crystallization Gibbs free energy (Δ G xtal) value from −72.9 to −35.7 J/g. This is primarily due to that the ability of SMO to stabilize wax nuclei and the role of γ-Al 2 O 3 nanoparticles as an additional nucleation site. Furthermore, DLVO analysis also revealed that γ-Al 2 O 3 nanoparticles exhibited high colloidal stability, enabling them to facilitate stable Pickering emulsion formation. Finally, microscopic observations demonstrated that both additives could suppress the formation of insoluble paraffinic "house of cards" crystals. [ABSTRACT FROM AUTHOR]