Production of cellulosic ethanol and lignin nanoparticles with UV-blocking potential through fractionation of corncob

Abstract

The present study developed a valorization scheme with corncob to generate bioethanol and lignin nanoparticles for sunscreens. Alkaline pretreatment with sodium hydroxide was proposed to fractionate the biomass. The pretreated corncob was evaluated in enzymatic hydrolysis and semi-simultaneous saccharification and fermentation (SSSF) under high solid loadings. Lignin was collected and modified by acetylation and converted into nanoparticles using atomization. Pretreated corncob showed increased crystallinity and 50.1% cellulose (1.6-fold increase) due to severe hemicellulose and lignin removal (49.8% and 86.8%). Pretreated corncob resulted in 43.0–51.9 g/L sugars for 5% (w/v) solids and 130.0–161.4 g/L sugars for 20% (w/v) solids. SSSF with Saccharomyces cerevisiae PE-2 achieved 38.2 g/L ethanol and a yield of up to 67.9%. The atomization apparatus led to the generation of lignin nanoparticles with sizes of 20–30 nm. The blends with 2% lignin nanoparticles presented a sun protection factor similar to those with 2% acetylated lignin, highlighting the role of particle size reduction in improving physicochemical properties. Given these results, the present study contributes insights into using and generating value from corncobs.