A Study on the Bleaching Properties of Locally Sourced Clay (Upkor Clay) For the Processing of Palm Oil

The bleaching properties of Ukpor Clay (a locally sourced clay) were studied and compared with that of imported bleaching earth for use in the bleaching of Crude Palm Oil. The effect of using the different bleaching earths on Free Fatty Acid and Peroxide value was evaluated. One factor at a time experiment was also used to determine the effect of Bleaching Temperature, Time and Adsorbent-to-Oil ratio and finally response surface methodology was used to study the effect of the three variables on bleaching on Palm Oil and determination of optimal bleaching conditions. It was observed that bleaching of Palm Oil increased the Free Fatty Acid content but reduced the Peroxide. It was also observed that FFA for the bleached palm oil reduces with increase in bleaching temperature, for both the imported bleaching earth and Ukpor clay, with the imported bleaching earth having a lower FFA value, about 1% below that of Ukpor clay, in all cases. The Bleaching efficiency increases with increase in temperature for both imported bleaching earth and Ukpor clay with the bleaching efficiencies of the imported bleaching earth and that of Ukpor clay being approximately equal at temperatures above 120OC. The bleaching efficiency also increases with increase in bleaching time or adsorbent-to-oil ratio for both imported bleaching earth and Ukpor clay. The three variables significantly affect bleaching efficiency at 95% confidence, with a good interaction among the variables. The optimum conditions for bleaching of crude palm oil using Ukpor clay are a temperature of 180OC for a time of 135mins and at an Adsorbent-to-Oil ratio of 0.05, at which it has a bleaching efficiency 80.50%. These results can be used to effectively exploit our locally sourced bleaching earth, especially in view of the contributions in this work and under the observed optimum conditions, for the processing or bleaching of palm oil.