Jul 22 2020
For over a century and a half, biodiesel has been produced from vegetable oil. This method considerably decreases various pollutants formed by the combustion of fossil fuels.
The two-phase system containing biodiesel (upper phase) and glycerol (lower phase). Image Credit: Gilberto Maia de Brito.
But it can be highly challenging to use vegetable oils in an engine, since it offers low power output and discharges exclusive toxic byproducts.
Scientists from Brazil have now illustrated a new chemical method for synthesizing biodiesel from domestic cooking oil waste. The method involves using a combination of hydroxide lithium and either potassium hydroxides or sodium hydroxides as catalysts.
The study was recently published in the Journal of Renewable and Sustainable Energy, by AIP Publishing, and could pave the way to further studies on the use of lithium from waste lithium-ion batteries.
The study is the first one to use lithium for these purposes. According to the study author Gilberto Maia de Brito, green engineering can provide solutions for a range of issues simultaneously.
The results achieved in this work will make it possible to expand the use of new types of metallic catalysts to a higher level, such as lithium, applied to the production of biodiesel. Before, in practice, these were just restricted to sodium hydroxide and potassium hydroxide.
Gilberto Maia de Brito, Professor, Department of Environmental Engineering, Federal University of Espírito Santo
The method developed by the team is based on a suggested solution for making biodiesel, known as transesterification, which can provide fuel in just minutes at room temperature.
The team collected waste cooking oil samples from homes and fast-food restaurants, some of the huge sources of waste disposed of improperly, and lithium hydroxide from waste lithium-ion batteries.
Upon catalysis by the mixture of metal hydroxides, the transesterification reaction breaks the cooking oil into a layer of glycerol and a biodiesel layer. The glycerol thus obtained can be used as such in several ways like mitigating some skin conditions, producing food sweeteners, and serving as an essential reactant in making antifreeze.
By using the correct proportions of catalysts, the researchers were able to make biodiesel with a yield of 90% on average. The group evaluate the purity of the synthesized fuel by analyzing the biodiesel through methods varying from infrared spectroscopy to chromatography to nuclear magnetic resonance studies.
We were surprised that what came out was not only some results, but actually very good results related to the yield production. The fast phase separation and the main chemistry and physics properties of that biodiesel produced from lithium were also surprising.
Gilberto Maia de Brito, Professor, Department of Environmental Engineering, Federal University of Espírito Santo
Maia de Brito seeks to continue his search for new techniques to retrieve lithium from waste and utilize it to further simplify biofuel production.
Journal Reference:
Maia de Brito, G. M., et al. (2020) Eco-green biodiesel production from domestic waste cooking oil by transesterification using LiOH into basic catalysts mixtures. Journal of Renewable and Sustainable Energy. doi.org/10.1063/5.0005625.