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The refining process of crude edible oil is based on four main operations: degumming, neutralization, bleaching and deodorization. The most critical and important step is bleaching, as it helps to improve the appearance, odor, taste and stability of the final products. During this step, the oil is put in contact with clay, called bleaching earth. This material has a large capacity to adsorb undesirable elements such as pigments (-αchlorophyll and β-carotene) and other residues (free fatty acids, phosphatides, soap residues and traces of heavy metals) that can be present in the crude oil. After having been used for the oil treatment, the bleaching earth loses its adsorption capacities and becomes a waste called spent bleaching earth (SBE). These solid waste containing up to 40% (w/w) of oil associated with other impurities, are generally disposed off in a landfill near the factory. As they are not treated, they may cause several management, storage and environmental problems, beside the unpleasant odors that can be produced. These environmental problems made the search for an alternative way to the landfill, a crucial matter. The main objective of this study was to contribute to reduce the pollution risk generated by these industrial wastes. The regeneration method used was based on a heat treatment of the SBE. The material obtained was a mixture of clay and coal and was then characterized by several techniques, namely: N2 isotherm at 77K, FTIR and XRD. Its adsorption performance was estimated through kinetic adsorption using a basic dye. In order to enhance the results, its adsorption capacities were then compared with those found in virgin bleaching earth (VBE) and in L27 activated carbon (purchased from PICA JACOBI). |
