Sodium titanate nanotubes for efficient transesterification of oils into biodiesel.

In this work, sodium titanate nanotubes were prepared by a hydrothermal method for 23 h at 160 °C and characterized by high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) methods, and Fourier transform infrared (FT-IR) spectroscopy. The obtained nanotubes were used as catalysts in the transesterification of pure and cooked oils under different experimental conditions (molar ratio, temperature, catalyst weight, and time). The catalyst showed high efficiency depending on the chosen conditions. The biodiesel yield was found to be 95.9% at 80 °C for 2 h. The catalyst also showed high activity for cooked oil conversion, with yields of 96.0, 96.0, and 93.58% for the first, second, and third uses of oil, respectively. The methanol was recycled and used in another transesterification experiment, and the biodiesel yield reached 91%. Density functional theory, Monte Carlo simulation, and molecular dynamics simulation were employed to clearly understand the transesterification mechanism. The transesterification reaction is represented by a pseudo-first-order kinetics model. Graphical Abstract .