Optimization of FeSO4-assisted sulfuric acid hydrolysis for improved sugar yield from sugarcane bagasse

• Autor(a) principal: Igbojionu, Longinus Ifeanyi [UNESP]
• Data de Publicação: 2020
• Outros Autores: Laluce, Cecilia [UNESP], Silva, João Pedro [UNESP], Silva, José Luiz [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1089/ind.2020.0020; http://hdl.handle.net/11449/228868
• topic: Acid hydrolysis; Design of experiment; Pretreatment; Saccharomyces cerevisiae IQAr/45-1; Sugarcane bagasse

Sugarcane bagasse (SB) consists of two major sugar polymers (cellulose and hemicelluloses) connected to lignin. Due to the recalcitrant nature of SB, pretreatment is considered a crucial process step before it can be converted to biomolecules. Raw SB consists of cellulose (40.4 wt%), hemicellulose (23.8wt%), lignin (27.2wt%), ash (3.0wt%) and extractives (4.4wt%). After pretreatment of SB with 8% sodium hydroxide at room temperature, the cellulosic fraction increased to 61.9wt%, while hemicellulose and lignin fraction decreased to 17.1wt% and 10.8 wt%, respectively. Design of experiment was employed to optimize FeSO4-assisted sulfuric acid hydrolysis conditions. The experimental results and predicted values showed strong agreement with high R2 value of 0.995. The highest glucose yield of 90.04% was obtained with 1.5% sulfuric acid, 40mmol/L FeSO4 and 120min, corresponding to predicted value of 88.98%. The optimum glucose yield was attained at high levels of FeSO4 and hydrolysis time, and a low level of sulfuric acid. After validation, the experimental and predicted values of glucose yield were 88.67% and 86.55% respectively, thus confirming the success of the optimization process. Also, the hydrolysates obtained were found to contain low amounts of inhibitory compounds (furfural and 5-hydroxymethylfurfural). Saccharomyces cerevisiae IQAr/ 45-1 efficiently converted the sugar present in the hydrolysate to achieve 82.2% of theoretical ethanol yield. Thus, this process, which involved the use of cheap chemical reagents to overcome SB recalcitrance and liberate fermentable sugars, could potentially support a biorefinery.