Determination of optimum conditions for thermal regeneration and characterization of a spent bleaching earth

Abstract

In this study, the optimal conditions of the thermal regeneration, for a spent bleaching earth (SBE) used to bleaching of soybean oil was evaluated. In order to determine the optimal conditions, it was used the response surface method (RSM). The UV-VIS spectrophotometry assays were performed in the soybean oil to determine the bleaching performance. The similarities and differences between the activated bleaching earth (ABE), the spent bleaching earth (SBE) and the regenerated spent bleaching earth (RSBE) (only best regeneration result obtained) samples were evaluated by means of atomic absorption spectrophotometry (AAS), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The bleaching performance of the regenerated spent bleaching earth (RSBE) ranged between 47.62–100 %, with the best result being obtained for assay at 600 °C during 90 min. The optimal conditions for the thermal regeneration suggested by model were 108 min at 587 °C (103%). The characteristics of the regenerated spent bleaching earth were similar to the activated bleaching earth (ABE).