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Cellulase treatment is a promising approach to activate dissolving pulp in terms of viscosity and reactivity. However, the enzyme cost is still too high, which hinders the scale up application. In this study, Tween 80 was introduced into the enzymatic system for improving the cellulase efficiency by improving the enzyme accessibility and its stability. Results show that the cellulose chain scission rate was more than 2 times higher with the addition of Tween 80 (0.1 g/L) in comparison to the control, which is mainly attributed to decreased surface tension (by 28.0% with the addition of 0.1 g/L Tween) and increased relative cellulase activity (by 9% at 48 h and 55°C). As a result, Tween 80 assisted cellulase activation gave a higher cellulasic efficiency in terms of viscosity decrease and Fock reactivity increase. Other pulp properties (alkali solubility, molecular weight distribution) and pulp yield were all favorable, supporting the conclusion that the Tween 80- assisted cellulase treatment process has a great potential to improve the cellulase treatment performance of dissolving pulp.

Suspensions of cellulose nanocrystals (CNCs) having different allomorphs were prepared from pulp and microcrystalline cellulose. Comparison found varying particle features. In situ observation of cellulose enzymes interacting with CNC I, II and III by atomic force microscopy (AFM) and transmission electron microscopy (TEM) found diverse adsorption of the enzymes on the CNC. Greater degradation to glucose was revealed for short rod-like CNC II and thin needle-like CNC III than CNC I, which were mainly due to their greater d-spacings for the (110) (CNC II) and (1–10) (CNC III) planes compared to the (200) spacing for CNC I. According to the model crystal structures, the surface areas for those planes where the enzymes would adsorb were also lager for CNC II and III. However, CNC III had significantly enhanced adsorption capability compared to the low affinity of CNC II. Enzymes tended to gather near hydrophobic surfaces that correspond to planes with small crystallite sizes on CNC III, and the enzymes caused breaks of nanocrystals during the degradation. Understanding the interactions between CNC allomorphs and cellulase would provide deep insights into biodegradation of crystalline cellulose as well as extensive application of CNCs.

Purification is an important approach to improve the added value utilization of xylo-oligosaccharides with 2–4 degree of polymerization (XOSDP 2–4) in pre-hydrolysis liquor (PHL). In order to improve the purification efficiency of PHL, rotary evaporation was explored to promote the inhibitor removal in poplar PHL. Influence of rotary evaporation on the composition and properties of PHL were investigated. After evaporation-Ca(OH)2-AC purification, the xylo-oligosaccharide in the purified PHL could be used to prepare XOSDP2−4 by enzymolysis of xylanase. The results showed that there was no loss of the total xylose/xylo-oligosaccharides during the rotary evaporation process, and evaporation also promoted the removal of lignin from PHL during the subsequent Ca(OH)2 and activated carbon (AC) treatment process, and the lignin removal increased from 57.80 % to 71.91 %. Furthermore, the furfural and acetic acids in PHL were separated and removed by condensation with the yields of 90.84 % and 23.63 %, respectively. 63.75 % of the XOSDP 2–4 yield was obtained after rotary evaporation-Ca(OH)2-AC purification and enzymolysis of xylanase based on the total xylose/xylo-oligosaccharides of the purified PHL with an increase of 25.12 % compared to the Ca(OH)2-AC purified PHL.

Reasonable utilization of lignin in pre-hydrolysis liquor (PHL) is very important for the economic benefit of papermaking industry. In this paper, lignin in poplar pre-hydrolysis liquor (PHL) was effectively adsorbed by TiO2 nanosheets, realizing the purification of PHL. Subsequently, lignin was carbonized via thermal desorption for forming the carbon quantum dots immobilized on TiO2 nanosheets surface, which can improve both the separation efficiency of photogenerated carrier and CO2 adsorption capacity of TiO2, as a result the efficiency of photocatalytic CO2 reduction of C/TiO2 increased 300 % compared to the TiO2.

Alcoholamine-based ionic liquid (IL) pretreatment has been potential due to low cost (∼$1.0/kg) and efficient delignification. However, valuable exploration of lignin during this pretreatment has not been systematically studied and this hinders its further commercialized application. In this study, the effects of mild and efficient ethanolamine acetate [EOA][OAc] pretreatment on the structural and thermal feature of Miscanthus × giganteus (M×g) lignin were evaluated in detail. The ionic liquid lignin (ILL), and residual-enzymatic hydrolysis-mild acidolysis lignin (R-EMAL) were compared with the original-enzymatic hydrolysis-mild acidolysis lignin (O-EMAL). Results determined that Guaiacyl (G) was the predominant unit in all the lignins. As compared to O-EMAL, ILL had higher yield, high purity, less β-O-4 ether linkages, and more COOH contents as well as a higher thermal stability owing to formation of slightly condensed structures. Additionally, depolymerization of the lignin occurred as the reduction of the molecular weight, and cleavage of β-O-4 ether linkages. Furthermore, R-EMAL was similar to O-EMAL as approximative β-O-4 ether linkages, molecular weight and thermal stability. The structural elucidation of M×g lignin could provide a good theoretical basis for economic improvement of the alcoholamine-based biorefinery and efficient conversion of lignocellulose to high value-added lignin-based products.

Reactivity is a critical parameter of dissolving pulp, which determines toxic chemical (i.e. carbon disulfide) consumption in rayon production. In this study, the depth refining was carried out to upgrade pre-hydrolysis kraft (PHK) pulp prior to cellulase treatment. The hypothesis is that the mechanical refining can not only increase reactivity by liberating additional hydroxyl groups, but also enhance cellulase efficiency by improving enzymatic accessibility. Results showed that the Fock reactivity of refined pulp (beating degree of 50°SR) was increased to 78.0 % from 54.8 % of the original (19°SR), which was mainly caused by inter- molecular hydrogen bond changes, supported by FTIR analysis. In addition, the cellulase adsorption ratio of refined pulp (30–50 °SR) was increased in a range of 39.7–71.2 %, which verified the improvement of enzymatic accessibility. As a result, the integrated process consisting of mechanical refining and cellulase treatment (at cellulase dosage of 0.5 mg/g pulp) yielded a much better result than the control (at cellulase dosage of 1 mg/g pulp) in terms of reactivity increase and viscosity decrease. Other pulp properties, such as fiber length and fines content, water retention value (WRV), specific surface area (SSA), crystallinity, and morphology, were all supported the positive effect of depth refining on activation of dissolving pulp during cellulase treatment.

Cellulose and starch are main chemical components of plant biomass, and can be used to produce value-added materials. Herein, cellulose nanocrystals (CNC) was used along with NaClO to prepare oxidized corn starch. Subsequently, the oxidized starch was blended with PVA/glycerol to prepare oxidized starch-based blends for film formation and coating paper. The properties of oxidized starch and film formability were modified by addition of CNC and PVA/glycerol. The oxidized starch showed the highest oxidizing degree at 1.10% with 0.5 wt% CNC and 8.0 wt% NaClO. Oxidized starch-based blends had lower viscosity and better uniformity than that of corn starch. The oxidized starch-based composite film showed the optimal water resistance, surface free energy and air permeability. Blending with 30 wt% PVA, the oxidized starch-based composite film showed the best tensile strength, and a simple structural model was simulated. The three-dimensional structure of coated paper was visualized using computed tomography scan (CT-Scan), and verified the good penetration of starch-based blends. The coated paper showed a more dense structure compared to the control paper, and had better waterproof performance and physical strength properties with oxidized starch with the highest oxidizing degree.

Forsythia suspensa, as a traditional Chinese medicinal herb, has been studied extensively. In this work, morphological and anatomical features of F. suspensa stem were examined by light microscopy (LM) and scanning electron microscopy (SEM). The results showed that the slenderness and Runkel ratio is 51 and 0.67, respectively. Anatomical observations indicated that F. suspensa is diffuse-porous wood. Helical thickenings and alternate intervessel pits are present on vessel cell wall. Transmission electron microscopy (TEM) images exhibited that the fiber cell wall is typically differentiated into three layers: middle lamella (ML), primary wall (P) and secondary wall (S1, S2 and S3), and the staining intensities represent differing lignin concentrations. Also, the confocal laser scanning microscopy (CLSM) and scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDXA) were used to investigate the lignin distribution in cell wall qualitatively and semi-quantitatively. Confocal images (488 nm) revealed a high level of lignin autofluorescence in the cell corner middle lamella (CCML), with lower levels of fluorescence in the compound middle lamella (CML) and S2 region. The results from SEM-EDXA demonstrated that lignin concentration ratio in different regions of fiber wall is 1.3 (CCML):1.1 (CML):1 (S2).