Vegetable oil-based microemulsions using carboxylate-based extended surfactants and their potential as an alternative renewable biofuel

► Salt-free surfactant system is formulated using extended-carboxylate surfactant. ► Decreasing diesel fraction increases the amount of surfactant required. ► Increasing diesel fraction decreases the viscosity of the microemulsion biofuel. ► Viscosity comparable to neat diesel can be achieved with surfactant-based systems.