Sugarcane bagasse valorization through integrated process for single cell oil, sulfonated carbon-based catalyst and biodiesel co-production

This study demonstrates the conversion of sugarcane bagasse (SB) into single cell oil (SCO), sulfonated carbon-based catalyst and biodiesel; this process aligns with waste-to-energy and circular bioeconomy concepts. SB was treated with dilute sulfuric acid to achieve SB hydrolysate (SBH) and SB solid residue (SBS). Candida tropicalis KKU-NP1, a newly isolated yeast, accumulated SCO content of 26.5 % from undetoxified SBH medium. A novel sulfonated carbon-based catalyst (SBS@SC) was generated from SBS by a one-step hydrothermal sulfonation process. It showed significant catalytic activity for the conversion of SCO-rich KKU-NP1 wet cell into biodiesel (FAME) under direct transesterification optimal conditions, with a FAME conversion yield of 90.1 %. Based on FAME profile, most of the estimated physicochemical and fuel properties of FAME were within the limits of ASTM D6751 and EN 14214 for biodiesel standards. For integrated process the final production of about 12.0 g SCO, 606.3 g SBS@SC catalyst and 10.8 g biodiesel from 1000 g raw SB were achieved. This study highlights the utilization of SB as a low-cost feedstock for producing multiple value-added products, emphasizing the advantages of waste utilization by integrated biorefinery concept, yielding practically no waste by-products over the whole production process.