Fates of hemicellulose, lignin and cellulose in concentrated phosphoric acid with hydrogen peroxide (PHP) pretreatment

Abstract

The transformation of cellulose, hemicellulose, and lignin in lignocellulosic biomass in a novel pretreatment are elucidated based on model fractions.

Pretreatment of Wheat Straw with Phosphoric Acid and Hydrogen Peroxide to Simultaneously Facilitate Cellulose Digestibility and Modify Lignin as Adsorbents

“…This was due to the cellulose and oligosaccharide degradation caused by an excessive amount of H 2 O 2 . These carbohydrates might be degraded by HO + or O• and OH• that were formed with higher H 2 O 2 input to form furfural, acetic acid and formic acid [21]. The addition of H 2 O 2 in amounts greater than 1.77% was not conducive to the recovery of cellulose-rich fractions and oligosaccharides.…”

“…Actually, the H 2 O 2 in the PHP pretreatment was responsible for releasing hydroxyl cations (HO + ) or free radicals, such as O•, OH•, which was mainly related to lignin removal by oxidation, as well as the possible modification on the recovered lignin [7,21,22]. To further elucidate the effects of H 2 O 2 input on lignin modification, the 31 P-NMR technique was applied to quantify the content of carboxylic hydroxyl groups, phenolic hydroxyl groups and aliphatic hydroxyl groups [35].…”

“…It was suggested that the ring-opening oxidation on those aromatic units was intensified with the increased of H2O2 input, and the content of carboxylic -OH was increased accordingly [21,22]. These results further explained the reason for the decreasing of typical aromatic ring absorption It was suggested that the ring-opening oxidation on those aromatic units was intensified with the increased of H 2 O 2 input, and the content of carboxylic -OH was increased accordingly [21,22]. These results further explained the reason for the decreasing of typical aromatic ring absorption bands in FT-IR spectra.…”

“…As a newly developed method, the concentrated phosphoric acid plus hydrogen peroxide (PHP) pretreatment, offers some outstanding features for pretreating lignocellulosic biomass, such as high enzymatic hydrolysis efficiency, mild conditions and wide adaptability to various raw materials (such as softwood, hardwood, agricultural residues and their mixture) [18][19][20]. When PHP pretreatment was used to fractionate lignocellulosic biomass into cellulose-rich fraction, oligosaccharides and lignin, the recovered PHP lignin (PHPL) exhibited attractive properties, i.e., high purity, low molecular weight and high content of carboxylic acid groups [21,22]. Based on these investigations, it was hypothesized that PHP can work as a bifunctional pretreatment to fractionate lignocellulose, which can potentially facilitate cellulose digestibility and modify lignin to produce adsorbents.…”

Enzymatic Preparation and Characterization of Spherical Microparticles Composed of Artificial Lignin and TEMPO-Oxidized Cellulose Nanofiber

“…Cellulose and lignin are two major components of wood cell walls [ 10 , 11 ]. Cellulose is a linear homopolymer composed only of β-D-glucopyranose, which forms crystalline microfibrils during biosynthesis owing to regular strong inter- and intra-molecular hydrogen bonds.…”