Modeling of Pretreatment Condition of Extrusion-Pretreated Prairie Cordgrass and Corn Stover with Poly (Oxyethylen)20 Sorbitan Monolaurate

Abstract

Extrusion processing has shown potential to be used as a pretreatment method for second-generation bioethanol production. Furthermore, surfactants have been shown to reduce enzyme deactivation and increase the efficiency of hydrolysis. Therefore, a sequential pretreatment technique was developed for corn stover (CS) and prairie cordgrass (PCG) in which a single screw extruder was used for the first pretreatment according to a previously optimized condition using 70-180 °C for feed, barrel, and die zones with 65-155 rpm screw speed. The second pretreatment was optimized in this study at 45-55 °C, 1-4 h, 0.15-0.6 g Tween 20/g glucan according to response surface methodology. Optimization of surfactant pretreatment facilitated the estimation of interaction and higher-order effects for major factors involved in surfactant treatment (temperature, time, surfactant loading). Using 8.6 FPU/g glucan cellulase, the optimum conditions found by fitting appropriate quadratic models to the data increased glucose and xylose yield by 27.5 and 33% for CS and by 21.5 and 27% for PCG, respectively. Tween 20 concentrations and pretreatment temperature were the most significant factors affecting sugar yield (p value <0.05). Studies of SDS concentration at and beyond critical micelle concentration (5.2-100 mM) demonstrated a decrease in sugar yield compared to control.

Response Surface Optimization of Enzymatic Hydrolysis of Sugar Beet Leaves into Fermentable Sugars for Bioethanol Production

“…The enzymes used in this experiment have been studied and reported on in other research works [39] [40] [41] [42]. The enzyme activities determined in this experiment are in the same range as those reported previously, as shown in Table 4.…”

“…The enzyme activities determined in this experiment are in the same range as those reported previously, as shown in Table 4. The xylanase activities for Cellic HTec that can be found in previous studies range from 1090 to 10,596 XU ml −1 [40] [41] [42]. Such a range might be attributable to the sensitivity of the activity measurement (due to the lack of linearity between enzyme concentration and product liberation) and the accuracy of the measurement since the measurement of xylanase activity is complex [26].…”

A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion

“…Studies that applied surfactants or protein-based amphiphiles during enzymatic hydrolysis of lignocellulosic biomass with cellulase and/or xylanase, reported that surfactants can increase sugar yield from lignocellulosic substrates [1,19,26,27,37,38,44,45]. In a typical procedure, pretreated biomass is incubated with nonionic surfactants (0.15 to 0.75 g/g glucan) [26,37,38] in a shaking incubator at temperatures of 50-60 °C for 1 h [44], or 15 min-4 h [1,26,36] prior to addition of cellulase.…”

“…Therefore, due to the significant need for improved enzyme activity, and the demonstrated effective action of protein and surfactant-based enzyme stabilizers, we review the different mechanisms of action of these additives on cellulase stabilization. Enhanced catalytic activity of cellulase with surfactants has been reported for a variety of substrates, including steam exploded spruce, lodgepole pine [27,[30][31][32], sigma cell 100 and steam exploded poplar [32], newspaper [33], Avicel and tissue paper [34], dilute sulfuric acid pretreated creeping wild ryegrass [29], Douglas fir exploded with SO 2 and ammonia freeze explosion (AFEX) pretreated corn stover, dilute acid pretreated corn stover [26,35], lime and ammonia recycled percolation (ARP) pretreated corn stover [26], extrusion pretreated corn stover and prairie cord grass [36,37].…”

“…As an alternative, protein-based lignin-blockers such as soybean meal, corn steep liquor, bovine serum albumin (BSA), amylase, chicken egg albumin, and combinations thereof [41], as well as casein [37] have been evaluated during enzymatic saccharification of high lignin containing biomass. Pretreatment techniques such as ammonia fiber explosion (AFEX), dilute acid (with Parr reactor), lime, washed SO 2 and Ammonia recycled percolation (ARP) pretreated corn stover, Douglas fir pretreated with SO 2 explosion and Avicel were used with prior treatment with bovine serum albumin (BSA) [1,41].…”