The Critical Analysis of Catalytic Steam Explosion Pretreatment of Corn Stalk, Lignin Degradation, Recovery, and Characteristic Variations

Abstract

The lignin degradation and its structural change as a result of catalytic steam explosion pretreatment can be considered of great importance for both the subsequent fermentation and the further utilization of the lignin fraction. This work investigated the degradation mechanism and change in the characteristics of lignin during dilute sulphuric-acid catalytic steam explosion (SE) pretreatment and ammonia catalytic steam explosion (AE) pretreatment of corn stalk. For this purpose, two types of lignin samples obtained from the two pretreatments of aqueous products and solid residues were fractionated, and they were then characterized by a series of comprehensive analyses that consisted of gas chromatography-mass spectroscopy (GC-MS), ion chromatography (IC), Fourier transform infrared (FT-IR), Carbon-13 nuclear magnetic resonance ( 13 C NMR), Carbon-Hydrogen two-dimensional heteronuclear single quantum coherence ( 13 C-1 H 2D HSQC), pyrolysis-GC-MS (Py-GC-MS), and field emission scanning electron microscopy (FE-SEM). Overall, the characteristic diversity of the lignin provides useful reference for highvalue applications of lignin.

Molecular Characterization of Water-Soluble Brown Carbon Chromophores in Snowpack from Northern Xinjiang, China

“…73 In addition, C 9 H 10 O 3 (#61) and C 12 H 16 O 4 (#63), two phenolic compounds with relatively lower O/C ratios, have been detected in lignin degradation products related to various decomposition processes such as thermal pyrolysis, 53,74 biodegradation, 75 and catalytic treatment. 76 The second group of CHO species identified as "f lavonoids" shows higher carbon numbers and O/C ratios than the phenolic/lignin-derived compounds (mean: 19 ± 4 and 0.45 ± 0.09, respectively; Table 1). These chromophores have two distinctive UV−vis absorption bands at wavelengths of 250− 270 nm and 330−350 nm (Figure 3c,d).…”

“…C 9 H 8 O 6 is probably carboxyvanillic acid from biodegradation of biphenyl lignin compounds by soil bacterials . In addition, C 9 H 10 O 3 (#61) and C 12 H 16 O 4 (#63), two phenolic compounds with relatively lower O/C ratios, have been detected in lignin degradation products related to various decomposition processes such as thermal pyrolysis, , biodegradation, and catalytic treatment …”

“…The group of phenolic/lignin-derived compounds contributes only 2−5% of the bulk absorbance. Within the shorter wavelength (e.g., <320 nm), the oxygenated aromatics group dominates the identified absorption (69, 40, and 52% for samples U1, U2, and R1, respectively), but its contribution decreases substantially at longer wavelengths (320−370 nm), where the nitroaromatics group becomes the major contributor (76,48, and 77% of identified absorption for samples U1, U2, and R1, respectively). For samples U1 and U2, chromophore #83 is the most light-absorbing species out of the oxygenated aromatics group, while it is chromophore #80 for sample R1.…”

Bamboo Lignin Fractions with In Vitro Tyrosinase Inhibition Activity Downregulate Melanogenesis in B16F10 Cells via PKA/CREB Signaling Pathway

“…Careful examination of lignin fractions from the solvent fraction process revealed a significant difference in the absorption at 1699 cm −1 , corresponding to conjugated ester linkage stretching, which was attributed to the ester bond of the phenolic acids to lignin [17]. This result indicated that the low-molecular-weight lignin fraction contained excess phenolic acids than the high-molecular-weight lignin fraction [18]. FT-IR is a useful approach for studying various functional groups as well as the conformational properties of lignin.…”

Combination pretreatment of steam explosion and NaOH enhances enzymatic saccharification of corn stove

“…The above-mentioned structural characteristics were explained by the fact that the SE-NaOH-pretreated CS had a high accessibility and low enzyme adsorption rate after enzymatic hydrolysis. This could have been because of the role that chemical high-temperature cooking plays in the degradation of hemicellulose and lignin, as well as the softening and exposing of cellulose (Yang et al 2017).…”