Regeneration and characterization of Spent Bleaching Clay

The spent bleaching clay (SBC), a solid waste generated from palm oil refinery, may be recycled rather than simply disposed off in landfill. The aim of this study is to investigate the heat regeneration of SBC and to evaluate the performance of the heat-treated SBC on the bleaching of crude oil. The quality of oil is first studied. The quality of the oil extracted from spent bleaching clay from palm oil refinery (SBC-PO) and spent bleaching clay from palm kernel oil refinery (SBC-PKO) much inferior compared to that of crude oil. De-oiling efficiency for both SBC increases as the solid to solvent ratio is decreased. Two type of SBC are studied such as acid-activated clay (XMP, WAC) and natural clay (AH). Two types of regeneration processes are performed, such as (a) solvent extraction followed by heat treatment and (b) regeneration carried out by direct heat treatment. Heat treatment is conducted in a box furnace at temperatures ranging from 400 to 1000°C. Red color indices of oils are used to determine the regeneration efficiency. Spent bleaching clay produced by direct heat treatment (HRSBC), yields a higher regeneration efficiency than the deoil-heat-regenerated spent bleaching clay (DHRSBC), produced by solvent extraction and heat treatment. The specific surface area, total pore volume and average pore size of SBC are measured using nitrogen adsorption-desorption method. The proximate analysis is also performed to clarify the mechanism of regeneration process. The data shows that the HRSBC at 500°C possess the highest specific surface area and total pore volume and give better bleaching efficiency than that of HRSBC at 400 and 800°C. All the regenerated SBC samples are mesoporous material. Adsorption isotherm is useful for determining the efficiency of the HRSBC in removing pigments. The Henry’s Law equation is found to be more applicable than the Langmuir and Freundlich isotherms in the adsorption of pigments from degummed palm oil on HRSBC. The adsorptive efficiency of the HRSBC is optimum at regeneration temperature of 500°C.

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