Use of ethanol associated with ionic liquids in the refining of vegetable oils, and in the production and modification of the physical properties of biodiesel

Abstract

Among the Sustainable Development Goals of the SDGs of the 2030 Agenda adopted by ONU is: "Ensure sustainable consumption and production patterns", including the sustainable management of chemicals, reduction of waste released to the environment and reduction of food waste. Considering that agriculture is responsible for approximately 25% of greenhouse gas emissions in the world, it is essential to develop new technologies that allow the improvement of the sustainable management of agricultural and industrial stages. Among the main agricultural matrices in the country, according to the last Census of Agriculture are sugar cane, with a production of 638 million tons, soybeans, with 103 million tons and cattle raising, with 11.5 million of cattle head. The processes for producing oils, fats and biodiesel, the main products derived from these matrices, use many organic solvents, including methanol and hexane. Despite the high process yields and low cost of these solvents, they are derived from petroleum and therefore, associated with greenhouse gas emissions and other impacts. In this context, the use of other solvents with more sustainable characteristics such as bioethanol or some ionic liquids synthesized from natural biocomposites, such as organic acids, is a very interesting alternative in several productive stages. Some examples are the processes of oil extraction, refining steps (deacidification) and transesterification for biodiesel production. Bioethanol has been selected as a solvent because it combines good performance in terms of extraction capacity, good selectivity, easy recovery, in addition to low toxicity. Bioethanol has also been used successfully in the homogeneous and heterogeneous catalysis of oils for the production of biodiesel. In fact, in the context of a biorefinery, the use of bioethanol in all stages of vegetable oil processing, from extraction to production of biodiesel, can be an economical and sustainable alternative. Another solvent that has been widely studied in this context is ionic liquids (LIs). In the last decade, the use of LIs pure or mixed with other solvents to improve the extraction yield of natural added value compounds of interest to the food and bioproducts industries, as well as in the reduction of high environmental impact residues generated by the catalysis processes for biofuel production has increased. Previous studies already carried out by the Research Group and which focused on the determination of phase equilibrium data, liquid-liquid and solid-liquid, involved in the extraction processes, refining of vegetable oils with ethanol as well as their thermodynamic modeling confirm these observations from other literature works. Despite this, there is still a great challenge and, at the same time, a great potential, the development of new extraction possibilities, more efficient and optimized, with the reduction of the toxicity of the outflow, choice of the best solvents or mixtures of them, solvents with better physical properties, final bioproducts with physical properties developed for specific purposes, such as lower viscosity, density, transition temperatures, among others. (AU)