Recuperação de acidos graxos livres em resina de troca ionica. / Recuperation of free fatty acids in ion exchange resins.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The drastic operational conditions used in the chemical or physical refining of edible oils can in some cases lead to losses of nutraceutical compounds, high losses of neutral oil or even to the darkening of the end product. Liquid-liquid extration can be used as an alternative refining process, since mild operation conditions are employed in this case. But it requires the recovery of the solvent, so that the extractant can be used again. Ion exchange resins can be employed as a complement to the liquid-liquid extraction, allowing the separation of the free fatty acids from the extract phase and the recovery of the solvent. This work investigate the equilibrium and cinetic behaviour of ion exchange in batch systems for separation of free fatty acids from a model system containing ethanol + oleic acid, that represents the extract stream of the liquid-liquid process. The behaviour in fixed bed was studied too, for the same system mentioned before and for a more complex model system containing ethanol + oleic acid + rice oil + g - oryzanol. Initially different types of resins were tested. The strong anion exchange resin were selected as the best one for the removal of the free fatty acid from the ethanolic solutions. The equilibrium experiments were conducted in a equilibrium cell, being investigated the influence of 2 parameters, the water content in the ethanolic solutions and the temperature. The equilibrium data were used for adjusting the parameters of the Langmuir Isotherm. It was verified that the temperature as well as the water content in the ethanolic solutions did not influence the Langmuir parameters. For this reason the water content in ethanol and the temperature were fixed (azeotropic ethanol and 25oC) in the best operational conditions. The kinetic studies were conducted using the adsortion in a batch way, being investigated the influence of 2 parameters, the stirring of the system and the initial oleic acid concentration in the solution. At the higher levels of stirring the external resistence to mass transfer were negligible and the effective diffusivity, Def, was estimated. A factorial design was used for the experiments conducted in fixed resin bed. By surface response analysis, the effect, upon the breakthrough curves, of two factors, feed stream and oleic acid content in feed stream, were investigated. The process was optimized using a objective function defined in terms of the efficiencies of solute recovery and resin saturation per breakthrough time. Both factors, feed stream and feed concentration, have positive effects upon the objective function. The breakthrough curves were also determined for a multicomponent system containing ethanol + oleic acid + rice brain oil + g - oryzanol.

ASSUNTO(S)

fatty acids resinas de troca ionica oils and fats ion exchange resin oleos e gorduras acidos graxos

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