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Highlights: [•] Redistribution of chemical compositions occurs during the process of size classification. [•] Glucan conversion is affected synthetically by the augment of surface area, lignin enrichment, and cellulose decrystallization that accompany with the process of size reduction. [•] Diversity of woody recalcitrance in bioconversion is reflected by the distinguishing responses of enzymatic digestibility to size reduction. [Copyright &y& Elsevier]

Abstract: Rejects from sulfite pulp mill that otherwise would be disposed of by incineration were converted to ethanol by a combined physical–biological process that was comprised of physical refining and simultaneous saccharification and fermentation (SSF). The energy efficiency was evaluated with comparison to thermochemically pretreated biomass, such as those pretreated by dilute acid (DA) and sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL). It was observed that the structure deconstruction of rejects by physical refining was indispensable to effective bioconversion but more energy intensive than that of thermochemically pretreated biomass. Fortunately, the energy consumption was compensated by the reduced enzyme dosage and the elevated ethanol yield. Furthermore, adjustment of disk-plates gap led to reduction in energy consumption with negligible influence on ethanol yield. In this context, energy efficiency up to 717.7% was achieved for rejects, much higher than that of SPORL sample (283.7%) and DA sample (152.8%). [Copyright &y& Elsevier]

Abstract: Old newsprint (ONP) could be deinked with laccase–violuric acid system (LVS). To study the mechanism of LVS deinking, lignins from the control and LVS-deinked pulp were isolated and characterized by chemical, spectroscopic and chromatographic methods. The molecular weight change of lignin was tracked by gel permeation chromatogram (GPC), and structural changes in lignin extracted from the control and LVS-deinked pulps were characterized by elemental analysis, functional groups measurement, FT-IR, 1H NMR and 1H–13C correlation 2D NMR. The experimental results showed that the molecular weight of lignin from LVS-deinked pulp was lower than that of lignin from the control pulp. The contents of free phenolic hydroxyl groups and methoxyl groups of lignin from LVS-deinked pulp decreased, while the contents of carboxyl and carbonyl groups increased. Guaiacyl units in lignin were oxidized by LVS. Stilbene and 5–5′ substructures in lignin were stable to LVS treatment, while β-O-4 and β–β substructures were partially destroyed during the LVS deinking. According to structural changes in lignin, the mechanism of LVS deinking was deduced. [Copyright &y& Elsevier]

This work aimed to construct a polysaccharide-based mulch film with good performance for replacing plastic mulch by coating the glutaraldehyde crosslinking chitosan and humic acid/urea complexes (GCS) into cellulose/humic acid (HA/CE) film. By flow-coating with GCS to construct hierarchical networks, GCS-HA/CE film is endowed with the improved property. The influences of composition with different concentrations on mechanical properties were studied, and the optimum concentration was determined. The tensile strength and elongation of GCS-HA/CE film could reach 53.97 MPa and 12.86 % in dry state, respectively. Results suggest that glutaraldehyde crosslinking reduces moisture content, water solubility, and water vapor permeability, but increases contact angle (94.025°). Meanwhile, the thermostability and ultraviolet resistance were improved. The infrared spectroscopy and X-ray diffractometry demonstrated the successfully crosslinked by glutaraldehyde. Morphological analyses present film has excellent compatibility. In addition, GCS-HA/CE film shows good heat preservation, aging resistance, and biodegradability, indicating certain guiding significance for polysaccharide-based mulch film. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline cellulose (NCC) isolated from bleached aspen kraft pulp was characterized, and its application as pulp strengthening additive and retention aid was investigated. Results showed that NCC with high crystallinity of more than 80% can be obtained using 64wt% sulfuric acid. The structure of nanocrystalline cellulose is parallelepiped rod-like, and their cross-sectional dimension is in the nanometer range with a high aspect ratio. The formation of microparticle retention systems during the application of NCC together with cationic polyacrylamide and cationic starch in deinked pulp was able to further improve pulp retention and strength properties without negative influence on the drainage. [Copyright &y& Elsevier]

Abstract: The effect of alkaline peroxide bleaching on the total anionic groups (AGs) and surface AGs in aspen chemithermomechanical pulp (CTMP) fibers was investigated. Alkaline treatment, especially alkaline peroxide bleaching resulted in the formation of new AGs and surface AGs in the CTMP fibers. The carboxylic groups in uronic acid units, including 4-O-methylglucuronic acid, galacturonic acid, and glucuronic acid units were the main contributors to the AGs in the fibers. However, the oxidized lignin accounting for more than 30% of the total AGs in the bleached CTMP fibers, was the main origin of the new AGs formed during the peroxide bleaching. In addition, the new AGs were also formed by extensive deesterification of the residual esterified uronic acids in pectins and lignin-carbohydrate complexes (LCCs). Although some uronic acid units were dissolved in the process water, both the total AGs and surface AGs in the fibers increased after alkaline peroxide bleaching. [Copyright &y& Elsevier]

Integrated fractionation process based on autohydrolysis (H) and subsequent formic acid delignification (FAD) has been considered as an effective strategy to separate the main lignocellulosic components in view of the biorefinery. For the better understanding of the structural changes of the lignin during the integrated process, the fractionated aspen lignins were thoroughly characterized by Fourier transform infrared (FT IR), 13C, two-dimensional heteronuclear single quantum coherence (2D-HSQC) and 31P nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). Compared to the milled wood lignin (MWL), the fractionated lignins had higher amounts of phenolic OH groups as due to the cleavage of β-O-4 linkages and less alcoholic OH groups mainly due to the esterification of the aliphatic OH groups by formic acid. Demethylation action of the lignin was not significant during the FAD process. More syringyl-propane (S) units were extracted during the H-FAD process than guaiacyl-propane (G) units resulting in a higher S/G ratio and more OCH 3 in the fractionated lignins. Furthermore, autohydrolysis of aspen at higher temperature led to more condensation of the fractionated lignins which exhibited higher molecular weight and more β-5 and β-β linkages. The fractionated lignins exhibited high purities due to the breakage of the lignin-carbohydrate bonds. • Lignin with high phenolic OH and OCH 3 and high purity was obtained. • Aliphatic OH group was highly esterified by formic acid. • β-O-4 cleavage accompanied by formation of condensed aromatic structure • Autohydrolysis led to higher molecular weight and less formate ester in lignin [ABSTRACT FROM AUTHOR]

The removal of lignin is important to the recovery of saccharides from the pre-hydrolysis liquor (PHL) in kraft-based dissolved pulp production. A one-step process for lignin removal from PHL via treatment with horseradish peroxidase (HRP) in the presence of Ca2+ was proposed, and its principle was studied. The results demonstrated synergy between HRP and Ca2+ in lignin removal from PHL, whereas NH 4 + had little effect on lignin removal. HRP treatment in the presence of 60 mmol/L of Ca2+ resulted in a lignin removal of 64.8% accompanied by a saccharide loss of 14.2%. HRP catalyzed both the polymerization and depolymerization of the lignin in the PHL. The HRP-catalyzed lignin polymerization rendered some lignin insoluble enabling it to be directly removed. The HRP-catalyzed depolymerization of lignin decreased its molecular weight with an evident increase in its carboxyl content. The insoluble complexes formed between the lignin with carboxyl and the Ca2+ facilitated the removal of the depolymerized lignin. • A new one-step process for effective lignin removal from PHL was proposed. • Synergy existed between HRP and Ca2+ in lignin removal from PHL. • HRP treatment in the presence of 60 mmol/L of Ca2+ yielded 64.8% lignin removal. • HRP treatment increased the carboxyl content of soluble lignin in PHL. • Complexes formed between Ca2+ and the carboxyl of soluble lignin to facilitate lignin removal. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystal (CNC) hybrid materials with numerous optical states have great potential as anti-counterfeiting labels and information encryption materials. However, it is challenging to construct multicolor emitting materials with tunable behaviors, which can dramatically enhance anti-counterfeiting abilities. Here, free-standing composite films with vivid multi-structural colors and dual-emitting fluorescence are successfully fabricated through a host-guest coassembly strategy. The lanthanide complex and an aggregation-induced emission molecule (tetraphenylethylene derivative, TPEC) are selected as luminescent guests, which are integrated into the chiral nematic structure of CNCs. The obtained photonic films display broadband reflection across the visible spectrum, which may be attributed to the chiral nematic domains with variations in the helical pitches and helical axis orientations. Under 254 nm excitation, the film exhibits bright red emission, while blue–green emission switching occurs under 365 nm excitation. The broad reflection band of the film covers both the green and red fluorescent emission centers, and right circularly polarized luminescence emission with different dissymmetry factors is produced due to the selective reflection of the left chiral nematic structure. A large glum value up to −0.21 at 600 nm was realized. Additionally, CNC-based materials with tailored shapes are further used in anti-counterfeit tags and decorative applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Bamboo chips were efficiently fractionated using an integrated process of autohydrolysis and formic acid to induce rapid delignification. Autohydrolysis pretreatment facilitated oligosaccharide production, while the subsequent rapid-delignification using formic acid at a low liquid/solid ratio with a relatively short reaction time allowed obtaining cellulose fibers and lignin. The major inter-unit linkages of side-chain in lignin were cleaved during the combined fractionation process. The lignin fraction exhibited higher purity, more phenolic OH groups, less condensed phenolic OH groups, and higher syringyl/guaiacyl ratio (S/G) as compared to MWL and formic acid lignin from the direct formic acid delignification. These results indicate that the combined fractionation process presents a promising approach to the commercial utilization in the biorefinery industry. [ABSTRACT FROM AUTHOR]

Formic acid/water binary solvent extraction with formic acid fraction lower than 77.5% (w/w) of azeotrope was used to extract hemicellulose-derived saccharides from poplar wood at various levels of severity. The highest xylose yield of 77.8% and arabinose yield of 93.5% were obtained at 120 °C and 1 h. To reduce cellulose hydrolysis and facilitate downstream xylose crystallization, mild conditions at 90 °C and 4 h was chosen as optimum severity, which led to the highest xylose fraction of 81.7% in all saccharides extracted, with a remarkable xylose yield of 73.1%. Mass balance analysis showed that 5.84% of xylan was degraded, but only 0.25% of xylan ended up as furfural at optimum severity. The proposed extraction process has high feasibility for industrial application since the low formic acid fraction in solvent allows simple recovery and concentration of used solvent. [ABSTRACT FROM AUTHOR]

Bamboo was fractionated using formic acid based on a one-step organosolv process under high pressure (at 145 °C for 45 min, 0.3 MPa) and at atmospheric pressure (at 101 °C for 120 min), respectively. High-pressure formic acid lignin, atmospheric formic acid lignin and milled wood lignin of bamboo were subjected to comprehensive structural characterization using gel permeation chromatography (GPC), Fourier transform infrared (FTIR) and solution-state NMR techniques ( 1 H, 13 C, 2D-HSQC, and 31 P-NMR spectroscopies). The results indicated that the formic acid fractionation under high pressure presents a quick and efficient delignification method by enhancing the cleavage of interunitary bonds in lignin (β-O-4′, β-β and β-5′), and dissolved lignin also occurred condensation reaction. As compared to atmospheric formic acid lignin, high-pressure formic acid lignin obtained showed higher purity and yield, and had relatively higher contents of phenolic and carboxylic groups. [ABSTRACT FROM AUTHOR]

In this study, the pre-hydrolysis liquor (PHL) was recycled during aspen chip water pre-hydrolysis, and the effects of PHL recycling on the extraction and accumulation of the hemicellulosic saccharides especially that with high molecular weight in the PHL were studied. The results showed that the concentration of hemicellulose saccharides in PHL depended on the pre-hydrolysis temperature and PHL recycling times. Compared to the unrecycled PHL, the concentration of hemicellulosic saccharides in PHL increased significantly when recycling PHL once or twice at 170 °C. Furthermore, the amount of high-molecular-weight hemicelluloses (HMHs) in PHL recycled once at 170 °C increased from 2.58 g/L (unrecycled) to 6.18 g/L, but the corresponding average molecular weight of HMHs decreased from 9.2 kDa to 7.6 kDa. The concentration of hemicellulosic saccharides in PHL decreased with PHL recycling time at 180 °C, accompanied by the formation of a significant amount of furfural. [ABSTRACT FROM AUTHOR]

A novel nanocomposite based on black wattle (BW) tannin and nanocellulose was prepared and applied in heavy metal ions adsorptive removal from aqueous solutions. Firstly, nanocrystalline cellulose was oxidized by sodium periodate to get dialdehyde nanocellulose (DANC). BW tannin was then covalently immobilized onto DANC, which was used as both the matrix and crosslinker, to obtain tannin-nanocellulose (TNCC) composite. The resulting nanocomposite was characterized using FTIR, AFM, and TG. The successful immobilization was confirmed by the chromogenic reaction between FeCl 3 and TNCC and FT-IR analysis. AFM images revealed that TNCC was ellipsoidal particles with lengths ranging from 100–400 nm. Zeta potential measurement showed that TNCC was negative charged at a pH range from 1–12. Compared to the original tannin, the thermal stability of TNCC was slightly increased by the addition of nanocellulose. TNCC demonstrated the maximum adsorption efficiency at pH 2 for Cr(VI) and pH 6 for Cu(II) and Pb(II), respectively. The adsorption for these three metal ions followed pseudo second-order kinetics, indicating the chemisorption nature. The adsorption isotherms all fitted well with the Sips model, and the calculated maximum adsorption capacities were 51.846 mg g −1 , 53.371 mg g −1 and 104.592 mg g −1 for Cu(II), Pb(II) and Cr (VI), respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Poplar was pretreated by reusable organic solvent under mild temperature (≤100 °C). • Almost all hemicelluloses and part of lignin was extracted with cellulose retained. • Sulfonic acid groups were introduced into lignin structure remained in substrates. • 89% improved glucose conversion compared with that of non-sulfonated substance. • New strategy is exploited to realize sulfonation and promote biomass bioconversion. Biomass pretreatment is an essential strategy to overcome biomass recalcitrance and promote lignocellulosic bioconversion. Here, a reusable organic solvent system (formic acid-methanesulfonic acid) was explored to pretreat poplar under a mild temperature (below 100 °C). The results showed that the co-solvent system could extract basically complete hemicelluloses and part of lignin with original cellulose retained in the pretreated substrates. Meanwhile, sulfonic acid groups were introduced into lignin structure remained in the substrates. The glucose conversion yield of the substrates with a higher concentration of sulfonic acid groups (13.2 mmol/kg) reached 45.9 % by reducing the hydrophobic interaction between lignin and cellulase, showing 89.3 % improvement compared with that of the substrates treated with single formic acid. This progressive study aimed to develop a new strategy to realize sulfonation and promote enzymatic hydrolysis of substrates by using mild organic solvent pretreatment. [ABSTRACT FROM AUTHOR]

Prehydrolysis of lignocellulose produces abundant hemicellulose-derived saccharides (HDS). To obtain pure HDS for application in food or pharmaceutical industries, the prehydrolysis liquor (PHL) must be refined to remove non-saccharide compounds (NSC) derived from lignin depolymerization and carbohydrate degradation. In this work, activated carbon (AC) adsorption was employed to purify HDS from NSC with emphasis on adsorption selectivity. The adsorption isotherms showed the priority of NSC to be absorbed over HDS at low AC level. However, increase of AC over 90% of NSC removal made adsorption non-selective due to competitive adsorption between NSC and HDS. Size exclusion chromatography showed that the adsorption of oligomeric HDS was dominant while monomeric HDS was inappreciable. The limited selectivity suggested that AC adsorption is infeasibility for HDS purification, but applicable as a pretreatment method. [ABSTRACT FROM AUTHOR]

A combined process of lime treatment and mixed bed ion exchange was proposed to separate hemicellulose-derived saccharides (HDS) from prehydrolysis liquor (PHL) of lignocellulose as value added products. The optimization of lime treatment achieved up to 44.2% removal of non-saccharide organic compounds (NSOC), mainly colloidal substances, with negligible HDS degradation at 0.5% lime level and subsequent neutralization by phosphoric acid. The residual NSOC and calcium ions in lime-treated PHL were eliminated by mixed bed ion exchange. The breakthrough curves of HDS and NSOC showed selective retention toward NSOC, leading to 75% HDS recovery with 95% purity at 17 bed volumes of exchange capacity. In addition, macroporous resin showed higher exchange capacity than gel resin as indicated by the triple processing volume. The remarkable selectivity of the combined process suggested the feasibility for HDS separation from PHL. [ABSTRACT FROM AUTHOR]

Prehydrolysis of wood biomass prior to kraft cooking provides a stream containing hemicellulose-derived saccharides (HDSs) but also undesired non-saccharide compounds (NSCs) that were resulted from lignin depolymerization and carbohydrate degradation. In this study, a combined process consisting of lime treatment, resin adsorption, and gel filtration was developed to separate HDSs from NSCs. The macro-lignin impurities that accounted for 32.2% of NSCs were removed by lime treatment at 1.2% dosage with negligible HDSs loss. The majority of NSCs, lignin-derived phenolics, were eliminated by mixed bed ion exchange resin, elevating NSCs removal to 94.0%. The remaining NSCs, furfural and hydroxymethylfurfural, were excluded from HDSs by gel filtration. Chemical composition analysis showed that xylooligosaccharides (XOS) with the degree of depolymerization from 2 to 6 accounted for 28% of the total purified HDSs. [ABSTRACT FROM AUTHOR]

The presence of transition metals during the hydrogen peroxide bleaching of pulp results in the decomposition of hydrogen peroxide, which decreases the bleaching efficiency. In this study, chitosans were used as peroxide stabilizer in the alkaline hydrogen peroxide bleaching of aspen chemithermomechanical pulp (CTMP). The results showed that the brightness of the bleached CTMP increased 1.5% ISO by addition of 0.1% chitosan with 95% degree of deacetylation during peroxide bleaching. Transition metals in the form of ions or metal colloid particles, such as iron, copper and manganese, could be adsorbed by chitosans. Chitosans could inhibit the decomposition of hydrogen peroxide catalyzed by different transition metals under alkaline conditions. The ability of chitosans to inhibit peroxide decomposition depended on the type of transition metals, chitosan concentration and degree of deacetylation applied. The addition of chitosan slightly reduced the concentration of the hydroxyl radical formed during the hydrogen peroxide bleaching of aspen CTMP. [ABSTRACT FROM AUTHOR]

Chiral nematic papers (CNPs) with mesopores structure based on cellulose nanocrystals (CNCs) were fabricated successfully via a swelling and freeze-drying method. The order of the original chiral nematic cellulose nanocrystals film was preserved in CNPs, which was proved by scanning electron microscopy (SEM), polarized optical microscopy (POM) measurements and circular dichroism (CD) spectra. The CNPs exhibited excellent optical responsive properties to different solvents. Inspired by this feature, a colorable ink containing amounts of gel particles was prepared by pulverizing CNPs/water mixture into a suspension. Patterns written in suspension ink with various colors can be formed when soaked with different solvents. Moreover, CNPs displayed an irreversible color response to compression. Additionally, the hydrophilicity of CNPs was tuned by polyethyleneimine. Modified CNPs exhibited different colors under the identical solvent environment when compared to the original one. Aqueous PEI can be used as an ink to depict responsive photonic patterns on CNPs. Iridescent chiral nematic papers (CNPs) with mesopores structure exhibit excellent optical responsive properties to mixed solvents. Modified CNPs with polyethylene imine (PEI) display different colors under the identical solvent environment when compared to the original one. Aqueous PEI can be used as an ink to depict responsive photonic patterns on CNPs. [Display omitted] [ABSTRACT FROM AUTHOR]

Saccharides and lignin components in prehydrolysis liquor (PHL) from kraft-based dissolving pulp production was characterized after being fractionated using membrane filtration. The results showed that the membrane filtration provided a method for organics fractionation with considerable recovery rate, but exhibited some disadvantages. Besides the limited ability in purifying oligosaccharides (OS) due to the overlaps of molecular weight distribution with lignin components, the membrane filtration could not improve the homogeneity of OS as indicated by the analysis of chemical compositions and the degree of polymerization (DP), which may be ascribed to the linear conformation of OS. The characterization of lignin components indicated a great potential for polymer industry because of the remarkable content of phenolic hydroxyl groups (PhOH), especially for low molecular weight (LMW) fraction. It was concluded the organics in PHL provided streams of value-added chemicals. However, the practical significance thereof can be realized and maximized only when they are successfully and completely fractionated. [ABSTRACT FROM AUTHOR]

Based on the formation of cellulose hydrogels in NaOH/urea aqueous solvent media, cellulose self-assembly precursor is acquired. It is proved that the water uptake capability of the cellulose hydrogels depends highly on the cross-link degree (CLD) of cellulose. With varying CLD and concentration of cellulose, a variety of morphologies of cellulose self-assemblies, including sheets with perfect morphology, high-aspect-ratio fibers, and disorganized segments and network, are formed through evaporation. Furthermore, cellulose films are fabricated by diecasting and evaporating the cellulose hydrogels, resulting in a 3D-ordered structure of closely stacking of cellulose sheets. The mechanical test indicates both tensile strength and flexibility of the cellulose films are greatly improved, which is attributed to the formation of the orderly stacking of cellulose sheets. The study is expected to lay an important foundation on the preparation of ordered and high-strength cellulose materials. [ABSTRACT FROM AUTHOR]

The effects of recycling on the microstructure and properties of bleached aspen chemithermomechanical pulp (CTMP) fibres were systematically investigated. The low-temperature nitrogen adsorption and atomic force microscopy results showed that a substantial amount of large pores and most of the very small pores in the fibre wall closed and the fibre surface became less coarse and porous during recycling. The partial cocrystallisation of cellulose microfibrils took place, as reflected in the increment of the cellulose crystallinity and the width of the crystallite in the 0 0 2 lattice plane. These irreversible structural changes caused significant hornification of the recycled fibres, leading to the loss of swelling and bonding capability. The decrease of the tensile index, burst index, and tear index further demonstrated the deterioration of the fibre properties. However, the single-fibre strength considerably increased after recycling, which was mainly due to the enlarged cellulose aggregates in the fibre wall. [ABSTRACT FROM AUTHOR]

The specific elimination of lignin derivatives from wood hydrolysate without sugar loss has great practical significance to biorefinery and bioenergy. In the present study, a process consisting of calcium hydroxide and anion exchange resin treatments was developed for the purpose of selective removal of lignin from wood prehydrolysis liquor (PHL). Particular emphasis was made on the ionization of phenolic lignin, and the subsequent binding to metallic salts. It was observed that phenolic hydroxyl groups (PhOH) in lignin played an important role in lignin removal. The results showed that up to 95.2% lignin was removed from PHL with 78.8% sugar recovery. This suggested that the proposed process is highly specific to lignin, and therefore can be envisaged as a great contribution to wood-sugar production or bioenergy conversion. [ABSTRACT FROM AUTHOR]

Highlights: [•] We studied the effects of acetone/water mixture coagulants on the properties of RC films. [•] The films from φ of 2.0 showed excellent dimensional stability and film-forming ability. [•] Small ions could be encapsulated and slowly released from the RC films. [ • ] The microstructure of the films changed greatly with varying φ. [ABSTRACT FROM AUTHOR]

Highlights: [•] The cross-linkage effect of cellulose/laponite hybrids was investigated. [•] Rheological measurements demonstrated a sol-to-gel transition triggered by loading of laponite. [•] The cross-linkage effect of cellulose/laponite hybrids was responsible for tensile strength enhancement of composite films. [ABSTRACT FROM AUTHOR]

Highlights: [•] OS recovery from HWE by specific lignin precipitation and subsequent dialysis. [•] Controlled charge neutralization by PAC for specific lignin precipitation. [•] Selective removal of large molecular lignin facilitates OS purification by membrane. [•] OS production from HWE by proposed process attains 56.36g per kg wood. [ABSTRACT FROM AUTHOR]

In analogue to the biorefinery concept, the separation process of lignocellulosic biomass is the most critical step to obtain its main components, namely cellulose, hemicelluloses and lignin. Moreover, the applied fractionation approach has a decisive impact on the characteristics and subsequent valorization strategies of the distinguished fractions. This review presents the state of art of novel biomass fractionation processes that are recently developed and focusing on autohydrolysis, organosolv fractionation, ionic liquid and deep eutectic solvent (DES) treatment. Moreover, the facing challenges, perspectives and future development direction in the field of fractionation of lignocellulosic biomass are discussed. The purpose of this review is to provide inspiration and guidance for fractionating biomass with environmentally friendly and efficient pathways, thus to push forward their further industrialization based on the integrated biorefinery concept. [Display omitted] • Green fractionation of biomass is a necessary process for biorefinery. • The recent advance of the leading fractionation technologies were reviewed. • The critical technical challenges for the discussed fractionation approaches were proposed. • The perspectives and future development direction of biomass fractionation were presented. • Fractionation processes should be upgraded to meet the industrialization requirements. [ABSTRACT FROM AUTHOR]

Ethanol extraction of lignocellulosic biomass under mild conditions has re-attracted considerable attention since a light-colored lignin with low molecular weight can be obtained. Unfortunately, the yield of isolated lignin for the ethanol extraction process is very limited. To enhance the extraction efficiency of lignin from poplar, ultrasound was used to assist the ethanol extraction and the isolated lignin was analyzed in terms of structure features and functional properties. As expected, increasing the ultrasonic power and ultrasonic time led to higher lignin yields during the ultrasound-assisted ethanol extraction (UAEE) process. The chemical structure of the isolated lignin (UAE-L) was almost completely retained, the C-O (mainly β-O-4) linkages in the lignin only exhibited a slight decrease, while the C-C (β-β, β-5, and β-1) linkages were nearly unchanged. The UAE-L was light in color and had more phenolic hydroxyl groups, less carbohydrate impurities, lower molecular weight and narrower polydispersity as compared to the poplar MWL. The UAE-L could scavenge more 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH·), displaying a stronger antioxidant activity. Moreover, the UAE-L showed good UV-absorbing properties in both UVA and UVB regions. These results indicated that the UAE-L has great potential for replacing the commercial synthesized antioxidant and anti-UV ingredients. The overall scheme of the isolation process of lignin from poplar by ultrasonic-assisted ethanol extraction (UAEE). [Display omitted] • Ultrasound was employed to enhance ethanol extract of lignin. • Light-colored lignin with abundant phenolic -OH and low molecular weight was obtained. • Lignin unit with less ortho- methoxy substitutions was preferentially released. • UAE-L showed good antioxidant activity and broad-spectrum UV-absorption capacity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pre-hydrolysis is considered as a promising technology in the biorefinery process. • "Pseudo-lignin" were formed and deposited on biomass surface during pre-hydrolysis. • The surface-deposits could be removed efficiently by isothermal phase separation. • More sugars were extracted by interrupting the formation of "pseudo-lignin". • The efficient removal of surface-deposits improved subsequent enzymatic hydrolysis. During the traditional autohydrolysis, formation and deposition of "pseudo-lignin" and lignin droplets on the surface of biomass had a detrimental effect on the subsequent biomass conversion. In this study, isothermal phase separation was introduced into autohydrolysis, and the effects of isothermal phase separation on the dissolution of components and enzymatic hydrolysis of bamboo were studied. The research showed that isothermal phase separation after autohydrolysis without cooling had an effective reduction in the deposition of "pseudo-lignin" and lignin droplets on the residues surface. After isothermal phase separation, the contents of sugar (14.05 g/L) and lignin (6.16 g/L) in pre-hydrolysates increased by 20% and 19% compared with control, respectively. Moreover, the efficient removal of "pseudo-lignin" and lignin droplets from cell wall surface could further promote the biological conversion of pretreated biomass (22% higher than that of control) during the subsequent enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]

Performance and efficiency of old newspaper (ONP) deinking by combining cellulase/hemicellulase with laccase-violuric acid system (LVS) were investigated in this study. Brightness, effective residual ink concentration (ERIC) and physical properties were evaluated for the deinked pulp. Fiber length, coarseness, specific surface area and specific volume were also tested. The changes of dissolved lignin during the deinking processes were measured with UV spectroscopy. The fiber morphology was observed with environmental scanning electronic microscopy (ESEM). Experimental results showed that, compared to the pulp deinked with each individual enzyme, ERIC was lower for the cellulase/hemicellulase-LVS-deinked pulp. This indicated that a synergy existed in ONP deinking using a combination of enzymes. After being bleached by H2O2, enzyme-combining deinked pulp gave higher brightness and better strength properties. Compared with individual enzyme deinked pulp, average fiber length and coarseness decreased a little for the enzyme-combining deinked pulps. A higher specific surface area and specific volume of the pulp fibers were achieved. UV analysis proved that more lignin was released during the enzyme-combining deinking process. ESEM images showed that more fibrillation was observed on the fiber surface due to synergistic treatment. [Copyright &y& Elsevier]

Abstract: An approach aiming at improving paper properties is to use laccase to copolymerize low-molecular weight phenols with the pulp before papermaking. The addition of methyl syringate (MS) gave a twice wet tensile index of unbleached kraft pulp with laccase treatment but had little effect on the dry tensile index and substantially decreased the brightness of pulp. The radical concentration in laccase-treated fibers increased up to 2.5 times of that in control sample after 60min. The radical concentration in laccase/MS-treated fibers increased up to 20 times of that in control sample within 2min, and a highest radical concentration (increased by near 65 times) was obtained after 40min. A strong agglutination of large-area fibers in handsheet was observed after laccase/MS treatment. The surface lignin coverage of the laccase-treated fibers increased from 54.96% (control) to 59.36%, while that of the laccase/MS-treated fibers increased only up to 55.22%. It is suggested that the graft of MS on fiber and degradation of surface lignin occurred simultaneously. The addition of MS can enhance the activation of fibers and extend the enzymatic oxidation of lignin within the cell wall. An increased bonding area of fibers resulting from interaction of laccase, MS and fibers via radical-coupling reaction maybe account for the significantly improved wet strength of pulp. [Copyright &y& Elsevier]