Changes in plant cell-wall structure of corn stover due to hot compressed water pretreatment and enhanced enzymatic hydrolysis

Abstract

Corn stover is a potential feedstock for biofuel production. This work investigated physical and chemical changes in plant cell-wall structure of corn stover due to hot compressed water (HCW) pretreatment at 170-190 °C in a tube reactor. Chemical composition analysis showed the soluble hemicellulose content increased with pretreatment temperature, whereas the hemicellulose content decreased from 29 to 7 % in pretreated solids. Scanning electron microscopy revealed the parenchyma-type second cell-wall structure of the plant was almost completely removed at 185 °C, and the sclerenchyma-type second cell wall was greatly damaged upon addition of 5 mmol/L ammonium sulfate during HCW pretreatment. These changes favored accessibility for enzymatic action. Enzyme saccharification of solids by optimized pretreatment with HCW at 185 °C resulted in an enzymatic hydrolysis yield of 87 %, an enhancement of 77 % compared to the yield from untreated corn stover.

Enhanced Enzymatic Hydrolysis of Poplar after Combined Dilute NaOH and Fenton Pretreatment

“…Pretreatment can also increase the effective absorbability of cellulase (Ding et al 2012), which certainly enhances the enzymatic hydrolysis. The formation of holes on the surface of the sample was consistent with previous observations (Kohlmann et al 1996) that hypothesized that the enzymatic hydrolysis of cellulose is dominated by a tunneling mechanism, that is, the enzyme complex acts on the cellulose by penetration (Zhou et al 2014).…”

“…4e). NaOH treatment also aims to break up the structure of the substrate, thus causes swelling, leading to an increase in internal surface area of the sample (Liu et al 2009b;Zhou et al 2014), as shown in Fig. 4c.…”

“…Lignocellulosic biomass feedstocks, like sugarcane bagasse Mesquita et al 2016), corn stover (Liu et al 2009a;Wang et al 2016), switchgrass (Li et al 2010), and wheat straw (Qiu and Chen 2012;Coimbra et al 2016), have already attracted much attention on the subject. However, the complex net structure of cellulose, hemicelluloses, and lignin hinders further utilization of lignocellulosic materials (Zhou et al 2014;Jung et al 2015). Its highly recalcitrant nature affects liquid penetration, enzyme activity, and enzyme accessibility (Jain and Vigneshwaran 2012;He et al 2015).…”

Innovative Deconstruction of Biomass Induced by Dry Chemo-Mechanical Activation: Impact on Enzymatic Hydrolysis and Energy Efficiency

“…However, steam pretreatment produced about 80% of glucose with an E n -factor of 70.0. 25 AFEX 26 and hot compressed water pretreatments 27 of corn stover produced about 90% of glucose resulting in an E n -factor of about 7.0 and 36.7, respectively. This difference, due to the quantity of water used in the pretreatment was 15 times higher for AFEX pretreatment.…”

Effect and optimization of NaOH combined with Fenton pretreatment conditions on enzymatic hydrolysis of poplar sawdust

“…Lignocellulose mainly consists of cellulose, hemicellulose, and lignin, in which cellulose and hemicellulose can be hydrolyzed into reducing sugars, then converted into biofuels by enzymes or microbes (7). However, lignocellulose is difficult to degrade due to its complex structure and the presence of lignin (8), which affects enzyme activity, fluid permeability, and enzyme accessibility (9), hindering the utilization of lignocellulosic materials. Therefore, pretreatment of the lignocellulose is necessary to break the compact structure and assist in the removal of lignin, thus promoting the contact between the cellulose and enzymes or microbes (10).…”