How variation of turbidity of bleached oils characterizes purity oil and bleaching processes

Abstract

Freundlich and Langmuir isotherms have always been developed using changes in absorbance of oils. In this study we have investigated use of changes in turbidity of oils to assess bleaching efficiency and develop Freundlich and Langmuir isotherms of bleached oils. Cotton and sunflower oils separately mixed with 1% acid activated clay and heated to and maintained at thermostated temperature for two hours, filtered and the turbidity of oil recorded using a turbidometer. The adsorptive capacity of clays measured in terms of percentage decrease in turbidity of bleached oil with clay activated by treatment of 25% sulfuric acid and bleaching performed at 90oC were 44%, 45%, 39% and 44% for Budadiri, Chelel, Kajansi, and Mutufu clays respectively. The bleaching efficiency of clay depended on acid concentration and the temperature of the activation which contribute to changes in clay structure. The acid leached clays decreased turbidity of cotton and sunflower seed oils by removing color pigments and other impurities. This was shown by values of k which ranged from -0.8200 to -1.2326; and n which ranged from-1.7805 to-4.952 and were in agreement with those published by Topallar (1998).