Enzymatic Hydrolysis of Corn Stover after Pretreatment with Dilute Sulfuric Acid

Abstract

Although many previous studies have been carried on the enzymatic hydrolysis of corn stover after pretreatment with dilute sulfuric acid, this paper emphasizes the use of different conditions to attain the highest yields of two sugars, xylose and glucose, from both stages. The pretreatment was performed at a range of sulfuric acid concentrations of 2, 4 and 6 % at 80, 100 and 120°C. Up to 77 % xylose yield was obtained while the glucose yield was only 8.4 %. The corresponding solid phase was hydrolyzed by cellulase and the influences of five factors and their interactions on enzyme hydrolysis were evaluated by response surface methodology based on one-factor-at-a-time experiments. The optimal levels for each variable to obtain the highest reducing sugar yield were as follows: enzyme concentration of 22 FPU/g substrate, substrate concentration of 77 g/L, temperature of 49°C, pH 4.8 and reaction time of 38 h. A reducing sugar yield of 42.11 g/100 g substrate was achieved, which was consistent with the predicted value of 42.13 g/ 100 g substrate. Compared with the one-factor-at-a-time experiments, there was a 9.4 % increase in reducing sugar yield when the enzyme concentration was decreased to 3 FPU/g substrate, the substrate concentration increased to 17 g/L and the reaction time dropped to 22 h. The total sugar released from the two stages was 62.81 g/100 g substrate.

Organosolvent pretreatment and enzymatic hydrolysis of rice straw for the production of bioethanol

“…Chen et al (2007) demonstrated the requirement of higher cellulase concentrations to corncob cellulose hydrolysis, verifying an increase in hydrolysis yield from 50 to 150 FPU/g substrate, although above 100 FPU/g substrate the raise was weaker. Tengborg et al (2001) studied the hydrolysis of whole slurry of steam-pretreated softwood with a cellulases loading until 120 FPU/g cellulose do not achieve a complete hydrolysis even after 120 h. Lu et al (2007) reached to saturation with an increase in enzyme concentration from 20 to 25 FPU/g with an optimum for cellulase concentration of 22 FPU/g substrate. These studies show that different biomass and different conditions of pretreatment and enzymatic hydrolysis reaction may lead to very different results.…”

Optimization of Alkali, Switchgrass, and Extruder Parameters for Maximum Sugar Recovery

“…RSM has been widely used in various fields ranging from food process operations including extrusion [15,16], new product development, biotechnology media composition, to bioprocessing, such as enzymatic hydrolysis and fermentation. Recently, RSM has been successfully applied to biomass pretreatment by many researchers [17][18][19][20][21][22]. Earlier extrusion pretreatment studies conducted by the authors yielded encouraging results; however, the alkali concentration and extrusion factors were not optimized.…”

Kinetic Study of Dilute Nitric acid Treatment of Corn Stover at Relatively High Temperature

“…F 0 varied slightly in the range of 3.68-5.35 g L - 1 . The values of k 3 and k 4 also increased with nitric acid concentration.…”

“…Corn stover, a waste in corn seed production, is an abundant and low-cost lignocellulosic material, which is commonly used as feedstuff or for the production of fuels and chemicals [1]. As one kind of biomass materials, corn stover could be converted to bioenergy such as bioethanol and biogas through biological processes.…”