A sustainable biorefinery approach for pomelo peel valorization: cellulose and pectin extraction with integrated ethanol recycling

BACKGROUND The valorization of pomelo peel for the production of cellulose and pectin was investigated by comparing two extraction approaches: co‐extraction (one step) and sequential extraction (two steps). The one‐step process was based on cellulose extraction: pomelo peel was treated with alkali, followed by the subsequent recovery of pectin in the liquid fraction. In contrast, the two‐step process began with conventional pectin extraction (pH 2.5, 80 °C), after which the remaining solid residue was treated with alkali to extract cellulose. RESULTS Evaluating both yield (based on raw material) and purity, the two‐step process produced 17.9% cellulose and 23.3% pectin, with purities of 62.0% and 68.7%, respectively. Compared to commercial cellulose, the cellulose obtained from the two‐step process exhibited higher water‐holding and swelling capacities. Additionally, the extracted pectin was classified as high‐methoxyl pectin. To make the process more sustainable and economical, the recovery of ethanol used for pectin precipitation and washing was investigated. The results showed that the recovered ethanol could efficiently precipitate pectin without affecting its properties, leading to a reduction in ethanol consumption of approximately 40%. The sequential extraction successfully produced two commercially viable products, with estimated chemical processing costs of 0.13 USD g −1 for pectin and 0.02 USD g −1 for cellulose. CONCLUSION Consequently, these findings serve as a foundation for sustainable biomass valorization by illustrating the successful recovery of multiproduct streams from a singular agricultural residue.