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1、ABSTRACT:The deacidification of corn oil by continuous liquidliquid extraction was investigated in a rotating disc col- umn. The solvent was ethanol containing approximately 6% water. The infl uence of rotor speed, oil phase fl ow, and column geometry upon the dispersed phase holdup and the mass tra
2、ns- fer efficiency was studied. The dispersed phase holdup in- creased with the increase of rotor speed and oil phase flow. Pratts equation was used for calculating the characteristic ve- locity. An inverse relation was observed between the character- istic velocity and rotor speed, which is differe
3、nt from data pre- viously reported in the literature. The estimated volumetric mass transfer coefficients increased as rotor speed and oil phase fl ow increased. The experimental results proved that it is feasible to obtain a refi ned oil with an oleic acid content less than 0.3 wt% by continuous so
4、lvent extraction. They also indicated that the corresponding loss of neutral oil was less than 5 wt%. Such value for the loss of neutral oil is signifi cantly lower than the re- sults reported in the literature for alkali or physical refining of corn oil. Paper no. J9349 in JAOCS 77, 553559 (May 200
5、0). KEY WORDS:Corn oil, deacidification, ethanol, extraction column, holdup, liquidliquid extraction, mass transfer, mass transfer coefficients, oleic acid, rotating disc contactor. Deacidification of edible oils can be accomplished by alkali refi ning, physical refi ning, or liquidliquid extraction
6、. Alkali refining is performed at temperatures in the range of 70 to 90C and requires centrifuges for neutralization and washing, resulting in higher investments and effluent treatment costs. For oils with high acidity, alkali refining causes high losses of neutral oil due to saponification and entr
7、ainment by the soapstock. Physical refining is performed at high tempera- tures (200250C) and very low pressures (510 mm Hg) (1). It involves high energy inputs and costly machinery. Liq- uidliquid extraction can be carried out at room temperature and atmospheric pressure, reducing the energy consum
8、ption for oil refi ning without losses of natural components. Because of the high difference between the boiling points of the sol- vent and fatty compounds, solvent stripping from refined oil and solvent recovery from extract stream can be easily car- ried out. In fact, both separations can be acco
9、mplished by evaporation or distillation at relatively low temperatures, in most cases lower than 80C. By using a moderate vacuum, for instance an absolute pressure of 250 mm Hg, this temper- ature can be further reduced to 55C. Especially in the case of oils having high acidity, the literature repor
10、ts that solvent extraction offers a promising alternative route for partial deacidifi cation (2,3). Oils from corn and rice bran have high acidity due to en- zymatic activity in the raw material. They need special care during refining by any process. According to Leibovitz and Ruckenstein (4), alkal
11、i refining of crude corn oil with a free acid content between 8 and 14% results in neutral oil loss of 15 to 25%, while for physical refining the loss of neutral oil varies between 11 and 20%. In the Brazilian oil industry, the neutralization process results in a neutral oil loss of 14% for corn oil
12、 containing 4% of free fatty acids (1). Shah and Venkatesan (3) studied oil refining by aqueous isopropryl alcohol extraction and Antoniassi et al. (5) studied oil deacidification by liquidliquid extraction, including the required pretreatment. Batista et al. (6,7) determined, corre- lated, and pred
13、icted the liquidliquid equilibrium for triglyc- erides, fatty acids, and short-chain alcohols. However, there is little information available about the performance of ex- tractors in the deacidification of edible oils. To study such performance, it is necessary to analyze the hydrodynamic be- havior
14、 and mass transfer phenomena inside the equipment under different operational conditions. With this purpose, we investigated the dispersed phase holdup and mass transfer in a rotating disc column for the corn oil/oleic acid/aqueous ethanol system. A specific feature of this system is the high viscos
15、ity of the oil phase (8,9), which is unusual as compared with most systems used for studying liquidliquid extraction. Our results proved the feasibility of the deacidifi cation of edible oils by continuous solvent extrac- tion and indicated that the neutral oil loss was less than 5%. EXPERIMENTAL PR
16、OCEDURES Apparatus and measuring procedures. The original rotating disc contactor (RDC) consists of a column equipped with a Copyright 2000 by AOCS Press553JAOCS, Vol. 77, no. 5 (2000) *To whom correspondence should be addressed at Food Engineering Depart- ment, Mail Box: 6121, UNICAMP, Cidade Universitria Zeferino Vaz, Campinas, So Paulo, Brazil 13083-970. E-mail: tomzeceres.fea.unicamp.br Deacidifi cation of Corn Oil by Solvent Extraction in a Perforated Rotating Disc Colum
