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Effect of mechanical disruption on the effectiveness of three reactors used for dilute acid pretreatment of corn stover Part 2: morphological and structural substrate analysis.

Ciesielski PN, Wang W, Chen X, Vinzant TB, Tucker MP, Decker SR, Himmel ME, Johnson DK, Donohoe BS - Biotechnol Biofuels (2014)

Bottom Line: After 96 h of enzymatic digestion, biomass treated in the SG and HS reactors achieved much higher cellulose conversions, 88% and 95%, respectively, compared to the conversion obtained using the ZC reactor (68%).Imaging at the micro- and nanoscales revealed that the superior performance of the SG and HS reactors could be explained by reduced particle size, cellular dislocation, increased surface roughness, delamination, and nanofibrillation generated within the biomass particles during pretreatment.Increased cellular dislocation, surface roughness, delamination, and nanofibrillation revealed by direct observation of the micro- and nanoscale change in accessibility explains the superior performance of reactors that augment pretreatment with physical energy.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biosciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO, 80401, USA.

ABSTRACT

Background: Lignocellulosic biomass is a renewable, naturally mass-produced form of stored solar energy. Thermochemical pretreatment processes have been developed to address the challenge of biomass recalcitrance, however the optimization, cost reduction, and scalability of these processes remain as obstacles to the adoption of biofuel production processes at the industrial scale. In this study, we demonstrate that the type of reactor in which pretreatment is carried out can profoundly alter the micro- and nanostructure of the pretreated materials and dramatically affect the subsequent efficiency, and thus cost, of enzymatic conversion of cellulose.

Results: Multi-scale microscopy and quantitative image analysis was used to investigate the impact of different biomass pretreatment reactor configurations on plant cell wall structure. We identify correlations between enzymatic digestibility and geometric descriptors derived from the image data. Corn stover feedstock was pretreated under the same nominal conditions for dilute acid pretreatment (2.0 wt% H2SO4, 160°C, 5 min) using three representative types of reactors: ZipperClave® (ZC), steam gun (SG), and horizontal screw (HS) reactors. After 96 h of enzymatic digestion, biomass treated in the SG and HS reactors achieved much higher cellulose conversions, 88% and 95%, respectively, compared to the conversion obtained using the ZC reactor (68%). Imaging at the micro- and nanoscales revealed that the superior performance of the SG and HS reactors could be explained by reduced particle size, cellular dislocation, increased surface roughness, delamination, and nanofibrillation generated within the biomass particles during pretreatment.

Conclusions: Increased cellular dislocation, surface roughness, delamination, and nanofibrillation revealed by direct observation of the micro- and nanoscale change in accessibility explains the superior performance of reactors that augment pretreatment with physical energy.

No MeSH data available.


Related in: MedlinePlus

SEM micrographs of biomass particle and cell wall surfaces. (a,a’) Control, (b,b’) ZC, (c,c’) SG, and (d,d’) HS. The left column reinforces the particle size reduction and clumping seen at lower resolution in the stereo micrographs. The right column shows changes in surface roughness of the biomass cell walls caused by pretreatment. Surface roughness measurements were calculated as the standard deviation of greyscale values within six selected regions of interest within three different SEM micrographs (orange square, inset). (e) The mean standard deviation of the greyscale values and standard deviation among the 18 surface roughness values is reported. HS, horizontal screw; SEM, scanning electron microscopy; SG, steam gun; ZC, ZipperClave®.
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Figure 4: SEM micrographs of biomass particle and cell wall surfaces. (a,a’) Control, (b,b’) ZC, (c,c’) SG, and (d,d’) HS. The left column reinforces the particle size reduction and clumping seen at lower resolution in the stereo micrographs. The right column shows changes in surface roughness of the biomass cell walls caused by pretreatment. Surface roughness measurements were calculated as the standard deviation of greyscale values within six selected regions of interest within three different SEM micrographs (orange square, inset). (e) The mean standard deviation of the greyscale values and standard deviation among the 18 surface roughness values is reported. HS, horizontal screw; SEM, scanning electron microscopy; SG, steam gun; ZC, ZipperClave®.

Mentions: Scanning electron microscopy (SEM) analysis was used to evaluate changes in particle deconstruction and particle surface area changes (Figure 4). The left column of Figure 4 (a,b,c,d) shows SEM views of the particle size reduction effect that was also revealed in the stereomicroscope images. The ZC reactor leaves larger, longer fibers intact (Figure 4b) and the HS reactor generates the smallest, most uniformly small particles (Figure 4d). The rightmost column in Figure 4 (a’,b’,c’,d’) shows higher magnification images of the cell wall surfaces that reveal the changes in surface roughness generated in the three reactors. Particle surfaces from all three pretreatment reactors display increased surface roughness compared to the control.


Effect of mechanical disruption on the effectiveness of three reactors used for dilute acid pretreatment of corn stover Part 2: morphological and structural substrate analysis.

Ciesielski PN, Wang W, Chen X, Vinzant TB, Tucker MP, Decker SR, Himmel ME, Johnson DK, Donohoe BS - Biotechnol Biofuels (2014)

SEM micrographs of biomass particle and cell wall surfaces. (a,a’) Control, (b,b’) ZC, (c,c’) SG, and (d,d’) HS. The left column reinforces the particle size reduction and clumping seen at lower resolution in the stereo micrographs. The right column shows changes in surface roughness of the biomass cell walls caused by pretreatment. Surface roughness measurements were calculated as the standard deviation of greyscale values within six selected regions of interest within three different SEM micrographs (orange square, inset). (e) The mean standard deviation of the greyscale values and standard deviation among the 18 surface roughness values is reported. HS, horizontal screw; SEM, scanning electron microscopy; SG, steam gun; ZC, ZipperClave®.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4022059&req=5

Figure 4: SEM micrographs of biomass particle and cell wall surfaces. (a,a’) Control, (b,b’) ZC, (c,c’) SG, and (d,d’) HS. The left column reinforces the particle size reduction and clumping seen at lower resolution in the stereo micrographs. The right column shows changes in surface roughness of the biomass cell walls caused by pretreatment. Surface roughness measurements were calculated as the standard deviation of greyscale values within six selected regions of interest within three different SEM micrographs (orange square, inset). (e) The mean standard deviation of the greyscale values and standard deviation among the 18 surface roughness values is reported. HS, horizontal screw; SEM, scanning electron microscopy; SG, steam gun; ZC, ZipperClave®.
Mentions: Scanning electron microscopy (SEM) analysis was used to evaluate changes in particle deconstruction and particle surface area changes (Figure 4). The left column of Figure 4 (a,b,c,d) shows SEM views of the particle size reduction effect that was also revealed in the stereomicroscope images. The ZC reactor leaves larger, longer fibers intact (Figure 4b) and the HS reactor generates the smallest, most uniformly small particles (Figure 4d). The rightmost column in Figure 4 (a’,b’,c’,d’) shows higher magnification images of the cell wall surfaces that reveal the changes in surface roughness generated in the three reactors. Particle surfaces from all three pretreatment reactors display increased surface roughness compared to the control.

Bottom Line: After 96 h of enzymatic digestion, biomass treated in the SG and HS reactors achieved much higher cellulose conversions, 88% and 95%, respectively, compared to the conversion obtained using the ZC reactor (68%).Imaging at the micro- and nanoscales revealed that the superior performance of the SG and HS reactors could be explained by reduced particle size, cellular dislocation, increased surface roughness, delamination, and nanofibrillation generated within the biomass particles during pretreatment.Increased cellular dislocation, surface roughness, delamination, and nanofibrillation revealed by direct observation of the micro- and nanoscale change in accessibility explains the superior performance of reactors that augment pretreatment with physical energy.

View Article: PubMed Central - HTML - PubMed

Affiliation: Biosciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO, 80401, USA.

ABSTRACT

Background: Lignocellulosic biomass is a renewable, naturally mass-produced form of stored solar energy. Thermochemical pretreatment processes have been developed to address the challenge of biomass recalcitrance, however the optimization, cost reduction, and scalability of these processes remain as obstacles to the adoption of biofuel production processes at the industrial scale. In this study, we demonstrate that the type of reactor in which pretreatment is carried out can profoundly alter the micro- and nanostructure of the pretreated materials and dramatically affect the subsequent efficiency, and thus cost, of enzymatic conversion of cellulose.

Results: Multi-scale microscopy and quantitative image analysis was used to investigate the impact of different biomass pretreatment reactor configurations on plant cell wall structure. We identify correlations between enzymatic digestibility and geometric descriptors derived from the image data. Corn stover feedstock was pretreated under the same nominal conditions for dilute acid pretreatment (2.0 wt% H2SO4, 160°C, 5 min) using three representative types of reactors: ZipperClave® (ZC), steam gun (SG), and horizontal screw (HS) reactors. After 96 h of enzymatic digestion, biomass treated in the SG and HS reactors achieved much higher cellulose conversions, 88% and 95%, respectively, compared to the conversion obtained using the ZC reactor (68%). Imaging at the micro- and nanoscales revealed that the superior performance of the SG and HS reactors could be explained by reduced particle size, cellular dislocation, increased surface roughness, delamination, and nanofibrillation generated within the biomass particles during pretreatment.

Conclusions: Increased cellular dislocation, surface roughness, delamination, and nanofibrillation revealed by direct observation of the micro- and nanoscale change in accessibility explains the superior performance of reactors that augment pretreatment with physical energy.

No MeSH data available.


Related in: MedlinePlus