Evaluation of reusability of bleaching earth in vegetable oil refining

Abstract

Purpose Unrefined vegetable oils contain triglycerides and free fatty acids as the main ingredient, but besides, they contain waxes, phospholipids, tocopherols, β-carotene, chlorophyll and other trace amounts depending on the type of oil. Most undesirable substances such as residues, free fatty acids and phospholipids are separated in the neutralization process of the oil refining. As a pigment, β carotene is separated by the bleaching earth (BE) in the bleaching process. The BE is disposed of as waste after the bleaching process. In this study, waste BE, which is allocated for disposal, has become reusable. Design/methodology/approach For this purpose, the oil is separated from the BE by solvent extraction under room conditions. AOCS Ba 3-38, TS EN ISO 734, ISO 15305 and TS 324 standard methods were used. Findings As a result of the analysis, it was found that 1% of oil remained in the recovered BE. The recovered BE containing 1% oil was carbonized at 550oC for 1 and 2 h. The BE obtained after this process was used in the bleaching process at a rate of 1%. Reuse attempts were repeated seven times, colour-opening capacities were measured and BET analyses were performed to establish a relationship between surface area-discolouration capacity and reusability. Originality/value This study demonstrates that recovery of waste BE can be performed and if this reusability considers in the industrial scale, it will save on oil refining costs and reduce waste.