Effect of ammonia concentration on emulsification characteristics of ammonia solution–biodiesel emulsion blends

Emulsifying ammonia in biodiesel provides an eco-friendly fuel for diesel engines by reducing NOx emissions. Research on this emulsification for diesel engines is still in its early stages with limited studies available. The characteristics of ABEF at various ammonia concentrations are unknown. Understanding these characteristics is critical to optimizing incorporation strategies of optimum ammonia concentration. This study examined ABEF behavior with ammonia concentrations of 1, 3, 5, 7, and 10 wt% of water content. We evaluated MDD, emulsion stability, DPA, and pH changes. Emulsions were prepared by mixing cooking oil biodiesel, water, ammonia solution, and surfactants using an ultrasonic homogenizer. Through the preliminary tests, we determined that the sonication for 10 min with 0.5 vol% surfactant and 10 vol% water achieved the best emulsion properties for ABEF. The results show that MDD in ABEF increased with ammonia concentration of up to 5 wt% but decreased above 10 wt%. The DPA also increased with ammonia concentration, reaching 2.85 % at 10 wt% compared with 2.52 % in the biodiesel emulsion without ammonia. Increased ammonia concentration increased pH, improving surfactant performance and emulsification stability. Emulsions with 5–10 wt% ammonia were more stable than those with 1–3 wt% due to stronger repulsive forces preventing droplet fusion. • A5-W/BD emulsion exhibits a high MDD, while A10-W/BD has a lower value. • Repulsion forces stabilize emulsions in high ammonia content. • The DPA for emulsion rises with the addition of ammonia. • IDD for ABEF can be maintained well for high ammonia content.