Spent bleaching earth as a source of oil and catalyst for renewable hydrocarbon conversion

Spent bleaching earth (SBE) is a solid waste generated by the vegetable oil refining industries. It contains entrapped crude oil, making its disposal challenging for industries. In this study, valorization of SBE for catalytic biodiesel conversion using alginate-SBE catalyst was explored. The alginate-SBE catalyst was synthesized using a simple impregnation method. It was characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), field emission scanning electron microscopy with energy dispersive X-ray (FESEM- EDX) and temperature programmed desorption of carbon dioxide (CO2/TPD) to assess its structural and morphological properties. The recovered bleached oil was optimally transesterified at temperature of 80 °C, oil-to-methanol ratio of 1:22, and catalyst loading of 9wt% within 2h production, achieving a maximum biodiesel yield of 93.35%. Reusability tests demonstrated that the alginate-SBE catalyst can retain >90% of initial activity after five cycles, highlighting its potential for practical applications. Gas chromatography-mass spectrometry (GC-MS) results indicated potential conversion of biodiesel to renewable hydrocarbons (C8-C15). This study highlights the dual benefits of utilizing industrial waste for both feedstock and catalyst support, promoting a cleaner and economically viable approach for biofuel generation.