Regeneration of a spent bleaching earth and its reuse in the refining of an edible oil

摘要

A spent bleaching earth from an edible oil refinery has been regenerated by thennal processing followed by washing with a solution of hydrochloric acid. Optimal regeneration conditions have been controlled by decolorization tests of a degummed and neuti-alized crude edible oil. Optimal values (temperature: 500°C, carbonization time: 1h, HCI concentration: 1M) gave a material as efficient as a virgin bleaching earth. The percentage uptake of chlorophyll derivatives and fJ- carotenoids calculated at 410 and 460nm, are respectively 92.8 and 95% for an oil processed by the regenerated spent bleaching earth, against 77.4 and 92.7% for the same oil processed by a commercial virgin bleaching earth. The results obtained after decolorization of an edible oil with a regenerated spent bleaching earth indicate that during the process, the resultant oil did not undergo any changes in the iodine value, the free fatty acid content and the saponification value.