Abstract
Biodiesel is a new replacement for various types of traditional fuels. There are many advantages of biofuel including renewable, less-flammability, and cheaper compared to traditional fuel, reduce greenhouse gas emissions, and others. However, the primary challenge of biofuel production in the large-scale production is related to purification of its unwanted impurities such as glycerol, water, methanol, soap/catalyst, free fatty acids, glycerides and others. Herein, glycerol is an unwanted impurity of biofuel that leads to problems including i) deposition in the bottom of fuel tank, ii) decantation, iii) engine durability problems, iv) setting problems, v) injector fouling, vi) storage problem, and others. Consequently, there are many ways to remove glycerol, and herein, the one alternative is extraction of glycerol from biodiesel via Natural Deep Eutectic Solvents. In this regard, the mixture of a methyltriphenylphosphonium bromide and ethylene glycol, as a Natural Deep Eutectic Solvent ais effective in removing glycerol from biofuel. In this work, we had investigated the formation mechanism of methyltriphenylphosphonium bromide and ethylene glycol, as a Natural Deep Eutectic Solvents, and then extraction of glycerol from biofuel via Natural Deep Eutectic Solvents via implementing Quantum Chemical Calculations using HyperChem software. The results imply that there are strong ionic and covalent interactions between bromine, methyltriphenylphosphonium and ethylene glycol according to optimized structures, bond length, energies, and others. Secondly, the extraction of glycerol from biofuel is mainly achieved via bromine ion of Natural Deep Eutectic Solvent, and the structure of Natural Deep Eutectic Solvent is remaining unchanged after this process, meaning its stability, and can be reused.