Determination of liquid-liquid equilibrium data for rice bran oil/fatty acid/ethanol/hexane systems

Abstract

Crude vegetable oils are obtained by solvent extraction, by mechanical extraction or by a combination of both methods. Solvent extraction has some advantages, like operates at lower temperatures and also can extract other desirable non-fatty components from seeds. Hexane is the usual solvent to extract oil by leaching, but it is highly flammable and is suspected to cause hazard to human health. Some studies begin to investigate the change of this solvent. Crude vegetable oils consist predominantly of triacylglycerols and free fatty acids, di and monoacylglycerols are also present in lower level. The refining processes of crude vegetable oils involve solvent stripping, degumming, bleaching, deacidification and deodorization. Vegetable oils can be deacidified by convention processes, such as alkaline and physical refining. Alkaline refining is applicable for all raw materials; however, it can result in great losses of neutral oil. For high acidity oils, physical refining is also a possibility, but can cause undesirable alterations in color and stability to oxidation. An alternative is the deacidification by liquid-liquid extraction, process carried out at room temperature and atmospheric pressure and causes lower loss of neutral oil. Biodiesel from vegetable oils is a renewable energetic source and is gaining acceptance and market. It consists of methyl or ethyl esters and belongs to ecological fuels because of its qualitative composition. The most common way to produce biodiesel is by transesterification, a reaction of triacylglycerols with methanol or ethanol. The low solubility of triacylglycerols in alcohols presents the necessity of using some another solvent to create a monophasic system and improve the diffusion of the reagents. The knowledge of behavior of all these systems of crude vegetable oil / solvents at different temperatures configures the principal topic in mass transfer operations and reactive mixtures. Taking into account, these work aims to determine experimental data for liquid-liquid equilibrium of systems of vegetable oil / fatty acid / ethanol / hexane.