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Enzymatic Regeneration of Spent Bleaching Earth for Sustainable Reuse in Edible Oil Processing

Year: 2025
Type: article
Abstract: Spent bleaching earths (SBEs) resulting from the refining of soybean oil contain significant amounts of residual oil and phosphorus, which pose an environmental and disposal problem. In this study, a sustainable biotechnological approach to reactivate SBEs through enzymatic hydrolysis with a commercial lipase under moderate conditions was investigated. In an initial 23 factorial experimental design, the effects of temperature (40–60 °C), enzyme amount (50–200 mg), and reaction time (4–8 h) were evaluated, with reaction time identified as statistically significant (p < 0.05). A second experimental design with lower enzyme concentrations (5–25 mg) validated a positive effect of enzyme dosage on phosphorus removal. This result was validated by a presence/absence test in which no phosphorus removal occurred in the absence of the biocatalyst. The best conditions (60 °C, 4 h, 5 mg enzyme) reduced the oil content from 10% to 5% and achieved 97% phosphorus removal. However, pigment removal efficiency was limited to approximately 34%, indicating partial restoration of the bleaching capacity compared to virgin earth. The enzymatic process also produced a nutrient-rich liquid hydrolysate containing Mg (16 mg/L), P (750 μg/L), and S (980 μg/L), suggesting potential use as a biofertilizer. Regenerated SBE demonstrated suitability for reuse in oil bleaching systems and potential applications in filtration and soil conditioning, providing a cost-effective and environmentally friendly alternative to conventional regeneration methods.
Source: Catalysts
DOI: 10.3390/catal15121110
Authors: Sofia Ramos Castillo, Michael Sierra De La Cruz, Jayson Fals, Pedro Orozco Cury, Mayerlenis Jiménez Rojas
Language: English
Open Access status: gold
Estimated APC paid: $2,654
OpenAlex ID: W4416848121
FWCI:
Cites: 30
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