SPENT BLEACHING EARTH: SYNTHESIS, PROPERTIES, CHARACTERISATION, AND APPLICATION

Spent bleaching earth (SBE) is hazardous solid waste generated from the edible oil industry through the oil bleaching process, as it is used to purify the edible oil to accomplish the strict standards required for edible oil on colour, taste and hence oil’s shelf-life. It has diverse applications for energy, construction, and agriculture, which are attributed to its remarkable physical and chemical properties. Waste generation can be reduced by utilising SBE for applications that include biogas production, bio-organic fertiliser, lubricating grease, and foamed concrete incorporating SBE. In line with this background, this paper compiled and reviewed the literature on the synthesis of SBE through the activation of bentonite, edible oil bleaching process, properties of SBE and characterisation techniques for SBE. Finally, the merits and demerits of the application of SBE are expounded. The overall performance of SBE in their respective applications is enhanced by free cations and residual oil present. Finally, future research considerations are also discussed for the co-pyrolysis application of SBE and other biomass substrates as an economically significant prospect. It is noted that reusing SBE appears to improve the oil refining industry’s sustainability and in turn the cities and communities.