Optimization of alkaline-assisted organosolv pretreatment of sugarcane trash for the production of succinic acid using response surface methodology

Abstract

The improvement of various pretreatment methods of lignocellulose biomass has been a major concern due to the cost involved, especially in the production of succinic acid which requires high carbohydrate content. Sugarcane trash is lignocellulosic biomass, which is the most abundant renewable carbon source. This study optimized the conditions of organosolv pretreatment of sugarcane trash using sodium hydroxide (NaOH) as a catalyst, to increase alpha-cellulose and decrease lignin content using response surface methodology based on Box-Behnken design with 3 factors (temperature, time, NaOH). Enzyme hydrolysis and fermentation proceeded after the pretreatment to produce succinic acid. The optimized conditions for the pretreatment include 140 °C, 60 min, and 20 wt% NaOH. In the validation experiment under these conditions, the alpha-cellulose content increased to 67.75% and lignin decreased to 5.41%. Enzyme hydrolysis of 10% substrate by Cellic Ctec2 (15 FPU/g substrates) resulted in 70.6 g/L glucose, 14.8 g/L xylose, 2.1 g/L arabinose, and 2.3 g/L cellobiose. Fermentation by Actinobacillus succinogenese TISTR 1994T using the hydrolysate containing glucose (35 g/L), xylose (10 g/L), and arabinose (5 g/L) resulted in 41.39 g/L succinic acid after 48 h of fermentation. The maximum succinic acid produced was 41.39 g/L at 48 h of fermentation. With the potential on obtaining high amount of cellulose, the work demonstrated the potential of the alkaline-catalyzed ethanol-based organosolv process for pretreatment of sugarcane trash in succinic acid production.