Influence of Structure and Base Modification of Zinc Oxide Nanostructures on Kinetic Parameters of the Transesterification of Rice Bran Oil to Biodiesel

Abstract

Biodiesel is an alternative to biofuel that could help to reduce the use of fossil fuels and protect the environment. Evaluation of reaction kinetics provides information on reaction rates and mechanism which is necessary in evaluating catalyst’s effectiveness. In this research, zinc oxide (ZnO) nanostructures, nanoparticles, nanoflowers and nanotubes were base-modified with potassium to enhance their active sites and used in the transesterification process for study of kinetic parameters. The nanocatalysts were characterized with FESEM and biodiesel conversion monitored with 1H NMR. The result shows that both structure and base modification have influence on the kinetics parameters. In all the catalysts, activation energy falls within 26-82 kJmol-1 indicating that the process was kinetically controlled and nanotubes has the highest rate constant of 0.0287 min-1, lowest activation energy of 59.40 kJmol-1 and highest turnover frequency (TOF) of 0.026 s-1. The results show that kinetic parameters of transesterification are not only defendant on catalysts’ basic or acid active sites but can also be influenced by structural modification. Therefore, the structural and K-modified ZnO nanoparticles have effect on the kinetic parameters of the tranesterification of rice bran oil (RBO) to biodiel and thus significantly reduce the use of fossil fuels in the environment.