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Lignin, as a main factor inhibiting the enzymatic hydrolysis of lignocellulose, was investigated by comparing lignin isolated from untreated and pretreated lignocellulose to elucidate the differences in the enzyme adsorption ability. The nonproductive adsorption of cellulase on lignin was investigated by using a quartz crystal microbalance with dissipation. The results indicated that more cellulase adsorbed on the lignin isolated from autohydrolysis and green liquor-pretreated lignocellulose than on protolignin. Higher temperature and enzyme concentration increased the initial adsorption rate and the amount of enzyme adsorbed on lignin. A dynamic equation for enzyme adsorption on lignin was established. The adsorption of enzymes on lignin increased as the content of phenolic hydroxyl groups, and β-β and β-5 linkages in the lignin increased, attributed to enhanced hydrogen bonding and hydrophobic interaction. Consequently, inhibition of the enzymatic hydrolysis of cellulose was promoted by a higher phenolic hydroxyl group, β-β, and β-5 content. The adsorption of the enzyme components on lignin followed the order: β-glucosidase > xylanase > endo-glucanase > cellobiohydrolase, as revealed by polyacrylamide gel electrophoresis analysis. Electrostatic interaction increased the adsorption of β-glucosidase and xylanase on lignin, while synergistic hydrophobic interaction and hydrogen bonding increased the adsorption of endo-glucanase and cellobiohydrolase on lignin. The results indicate that the adsorption of enzymes on lignin is affected by the structure of lignin and the composition of the enzymes. The findings of the current study provide fundamental knowledge for improving the enzymatic conversion of lignocellulose.

The natural world abounds in lignocellulosic biomass, which is an environmentally friendly renewable resource. Cellulose nanofibrils (CNFs) made from biomass have the advantages of high optical transparency, light weight, good mechanical properties, high specific surface area and biodegradability. Increasing applications of CNFs have been identified in emerging high-tech fields, such as flexible electronics and clean energy. A variety of thermal management materials have been discussed in flexible electronic products. This paper reviews the merits of CNFs compared to other polymers in flexible electronic products and emphasizes the application status of CNF-based thermal management materials in flexible electronic products. The thermal conductivities of the CNF-based composites are analyzed with respect to the heat transfer mechanism, the thermal conductivity of the polymer, the loading of the filler, the size and morphology of the filler, the type of filler, and the surface treatment of the filler. Current challenges and future research opportunities are also discussed, offering a reasonable and scientific route for the structural design of future flexible thermal management materials that will promote the development of the flexible electronics industry.

A novel highly efficient technology, intimate coupling photocatalysis and biodegradation (ICPB) for the treatment of refractory organic pollutants was introduced, and the carrier in ICPB based on sugarcane bagasse cellulose (SBC) was prepared. The SBC–TiO2 carrier produced was characterized using spectroscopy, microscopy, and diffraction techniques. The SEM image showed a rough and porous structure of the carrier, while as the EDS, XPS and XRD indicated that TiO2 was successfully added into the carrier, which retained its original crystal structure and provided the photocatalytic activity. The combined process of photocatalysis and biodegradation was much more efficient than a single process alone. The success in preparing bagasse cellulose based carrier in this study provided a significant contribution towards the development of a green and efficient technology system for the treatment of refractory organic matter.

A novel biomass pulp fibre (PF)-based colorimetric sensor was prepared by grafting l-lysine (l-lys) onto the surface of PFs via a Schiff base reaction. The grafted l-lys contained two specific synergistic recognition groups (–COOH and –NH2), which only recognize Ag+. The as-prepared sensor (DAPF-l-lys) showed excellent selective recognition of Ag+ and an obvious visual colour change from light-yellow to brown in aqueous solutions containing other ions (Cu2+, Pb2+, Mn2+, Mg2+, Cd2+, Ca2+, H2O, Al3+, Hg2+, Cr6+, K+, Na+ and Zn2+). The visual limit of detection for Ag+ was 10–7 mol/L. Furthermore, DAPF-l-lys responded to Ag+ within 30 s based on the dynamic conditions of the detection method. The biomass PF matrix possessed the excellent properties, including a large external surface area, a short transit distance and good flexibility. When specific synergistic recognition groups were grafted onto the PF of the prepared PF-based colorimetric sensor, Ag+ could be rapidly absorbed and enriched on the surface of DAPF-l-lys through only bi-dentate ligand chelation between Ag+ and the synergistic recognition groups (–COOH and –NH2) of DAPF-l-lys. Thus, the DAPF-l-lys colorimetric sensor exhibited promising prospects for on-site identification of Ag+ (the level of ppb) due to its high selectivity and sensitivity.

Due to energy crisis and environmental pollution, biopolymer-based packaging materials have been extensively investigated. Cellulose nanofibrils (CNFs), due to their good oxygen barrier performance and excellent mechanical as well as film-forming properties, have emerged as interesting packaging materials. However, the problem of the resulting films is the highly hygroscopic character of the cellulose fibers themselves, which would further lead to a decrease of the films’ mechanical and barrier properties. Herein, a facile preparation of hydrophobic CNF films was carried out by the attachment of 10-undecylenoyl chloride onto CNFs followed by vacuum filtration. The modified CNFs became thicker and rougher compared with the pristine CNFs and were easy to disperse in ethanol. The resulting CNF film showed a higher surface roughness and a tensile strength of (47 ± 4) MPa. Additionally, the modified CNF film was hydrophobic, leading to an obvious barrier improvement with the WVP value decreasing by 62.4% in comparison to the pristine CNF film. Since this hydrophobic CNF film is easy to prepare with a good vapor barrier property, it should be promising for packaging applications. Furthermore, the generated CNF film demonstrated good reactivity with thiol groups, which can be applied for further functionalization to enrich their application fields.

This study investigated effects of residual lignin on composition, structure and properties of cellulose fibrils and cellulose fibril-based films by comparing two groups of cellulose fibrils which contained different amounts of lignin (15% and 2%, respectively) but were similar in cellulose to hemicellulose ratio. The results showed that lignin affected the size and content of nanofibril in cellulose fibrils through initially delaying but ultimately facilitating the mechanical defibrillation. Due to higher thermal stability and strong UV absorption capability, lignin enhanced the thermal stability and UV blocking properties of cellulose fibril-based film. Hydrophobic lignin also improved the dewatering of cellulose fibrils and the hydrophobicity of cellulose fibril-based film. Lignin interfered with the interfibrillar hydrogen bonding and therefore increased the mesopore diameter of cellulose fibril network. Lignin acting as a cement in cellulose fibril-based film made the film with a more densely packed structure, a higher density and a smoother surface. However, lignin decreased the transparency of cellulose fibril-based film due to its chromophore groups and impaired the mechanical strength of cellulose fibril-based film through interfering with the interfibrillar hydrogen bonding.

Bagasse fibers are smaller and have more hemicellulose than softwood fibers, which is expected to require less mechanical energy in cellulose nanofiber production as small size and hemicellulose benefit the disintegration of fibrils during a mechanical process. Both bagasse fibers and softwood fibers were used in this investigation for producing nanofibers with enzyme pretreatment followed by mechanical grinding. Results showed that nanofibers from bagasse had more uniform diameters about 9 nm, and the films made from them were more transparent. Grinding energy consumption of bagasse fibers was significantly lower than softwood, by 7.31%, and enzyme pretreatment further improved the energy efficiency, by 59.71%, and the yield of nanofibers, by 30.57%. The mechanical strength and thermal stability of nanofiber films from bagasse fibers were similar with that from softwood fibers. The results support the idea that bagasse, a waste or byproduct from sugar industry can be a promising alternative for nanofiber production.

High (14.9%), medium (2.4%) and low (0.1%) lignin-containing cellulosic fibers were processed through a micro-grinding method to mechanically produce lignocellulose nanofibrils (LCNFs). Effects of residual lignin on the mechanical defibrillation process were investigated in terms of the nanofibrils yields, the diameters of resultant LCNFs and the micro-grinding energy consumption. The results showed that the residual lignin delayed the initial defibrillation of cellulosic fibers due to its physical barrier. However, the residual lignin eventually facilitated the defibrillation and improved the maximum nanofibrils yields by 17.9–30.8%, and greatly reduced the diameters of the resultant LCNFs from 32.9 ± 7.7 to 9.2 ± 3.3 nm. The effects of lignin on counteracting the recombination reactions between the highly reactive cellulose radicals and hindering the aggregation of defibrillated fibrils through reducing the inter-fibrillar hydrogen bonding presumably resulted in the better eventual defibrillation of cellulosic fibrils.

Pretreatment of sugarcane bagasse pulp by hot chlorine dioxide has been performed to study delignification and structural changes in lignocelluloses. The compositions of the products were measured by gas chromatography mass spectrometry. The structure and morphology of the D-hot pretreated sugarcane bagasse pulps were characterized by FTIR, scanning electron microscope, X-ray diffraction, Metso Kajaani FS300 fiber analyzer and optical analyzer. Temperature played a crucial role in the lignin depolymerization and hemicellulose hydrolysis. The results show that the lignin content was reduced by 28.39% in the P layer and 20.93% in the S layer with increasing temperature from 60 to 95 °C. The resulting compositions of D-hot stage effluent were mainly including oxidized lignin and derivatives of furfural. Compared with the control, the category of oxidized lignin can be increased with D-hot pretreatment. Also, pretreated bagasse pulp has high brightness of 59.71% ISO, crystallinity index of 70.84%, L/W of 50.84 and outstanding optical properties. Therefore, bleached bagasse pulps might have the opportunities for further application in paper and paper-based materials. The graphical abstract showed that the changes of the crystallinity index (CrI), the brightness, and the L/W of the SCB pulp fibers with increasing reaction temperature from 60 to 95 °C. Also showed that the cross section of the single fiber and the region of P and S layer. EDS images of P and S layers for the unbleached SCB pulp, control pulp and D-hot bleached SCB pulps, the peaks corresponding to elemental carbon and oxygen were shown for the samples. In EDS, oxygen/carbon atom ratios and lignin mass in P and S layer of the unbleached pulp and bleached pulps were determined. The degradation products of lignin (1)–(3) in the control and degradation products (2)–(15) in the D-hot effluent were identified.

To study the effect of mechanical treatments on the rheosedimentation behaviour of pulp fiber suspensions, the settling behaviour, gel point, compressive yield stress and hindered settling function of bleached softwood pulp with different beating degrees at low concentrations were investigated. Over the range of test concentrations, it was found that the settling rates for refined softwood pulps were slower than that without mechanical treatments, and the values of gel points increased approximately linearly with freeness; Both the compressive yield stresses and hindered settling functions of all pulp suspensions increased non-linearly with increasing crowding number, and the hindered settling function was found to be dependent on the crowding number through a power law relationship. Moreover, the compressive yield stresses for softwood pulp suspensions with mechanical treatment were higher than that without refining. However, the same tendency for hindered settling functions was observed only for suspension at crowding number more than 16. The rheosedimentation studies on softwood pulp suspensions revealed that fiber morphology has a great influence on the settling and compressive behaviour.

This work describes the effect of the hot chlorine dioxide delignification (DHT) on the properties of bagasse fiber and the formation of AOX. The bagasse pulp was subjected to both DHT and normal temperature chlorine dioxide delignification (D0), and the AOX contents in the effluent were determined respectively. The GC–MS results showed that the main components of the D0 stage wastewater were chlorinated hydrocarbons and chlorinated diphenyls. In contrast, those AOXs in the DHT stage wastewater were very few. The GC–MS, ATR-FTIR, and XPS results showed the DHT process is more effective in the removal of the residual phenolic lignin and the hemicellulose-linked HexA compared with D0. Furthermore, in comparison, the AOX content could be reduced by 50% with DHT. The fully bleached pulp obtained via DHTEpD process has a higher brightness than that obtained by D0EpD, which provides a reliable theoretical basis for industrial application.

Wheat straw was respectively pretreated by water, dilute sulfuric acid, and sodium hydroxide solution at elevated temperature. Among the pretreatments, hydrothermal process was carried out with different severities. Hydrothermal pretreated sample and dilute acid pretreated sample were subsequently extracted by sodium hydroxide solution at room temperature which was applied as post-treatment. The pretreated samples were then enzymatically hydrolyzed to evaluate reducing sugar recovery. The result indicated that alkaline pretreatment removed a significant amount of lignin. While hydrothermal pretreatment and dilute acid pretreatment solubilized a significant amount of hemicellulose. And the hydrothermal pretreatment severity affected the solubilization of hemicellulose. The alkaline pretreated sample achieved the highest reducing sugar recovery e.g. 38.5 g sugar/100 g wheat straw. The alkaline post-treatment enhanced the enzymatic hydrolysis of acidic pretreated samples by removing additional hemicellulose and lignin. The best reducing sugar recovery was obtained at 43.6 g sugar/100 g wheat straw which indicated that the combination of hydrothermal pretreatment and alkaline extraction is a promising method in terms of reducing sugar production.

This article describes the preparation of novel aqueous spongy foams that are composed of three-dimensionally distributed wood-fiber networks stabilized with nanofibrillate cellulose (NFC) and/or microfibrillated cellulose (MFC). The free standing aqueous spongy foams were prepared with the entrapment of NFC and/or MFC—stabilized air-in-water (A/W) capillary foams using “gel trapping technique”. The stability of spongy foams could be controlled by manipulating the volume fraction of NFC and/or MFC and a secondary liquid immiscible with the continuous phase of the NFC and/or MFC suspension. Possible morphology and mechanical distribution of NFC and/or MFC within spongy foams were verified with optical microscope, SEM, and functional load-bearing method. Owing to three-dimensionally dispersed wood-fiber structure, ultra-lightweight (0.01–0.06 g/cm3), high porosity (>90%), and microporous (10–80 μm), the NFC and/or MFC reinforced spongy foams, improved compressional strength-vertical direction obviously, from 0.0 to more than 13.78 kPa.