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This work demonstrated a green process using deep eutectic solvent (DES) treatment for properties improvements of bamboo dissolving pulp. Results showed that an acidic DES, namely choline chloride-oxalic acid, was the most effective compared to other acidic, alkaline and neutral DESs. Upon the optimum acidic DES treatment (pulp to DES ratio 1:10, 60 °C and 30 min), the pulp viscosity was reduced from 715 mL/g of original pulp to 466 mL/g, while the pulp reactivity increased from 43.0 to 88.1%. The positive results were mainly ascribed to a synergy during the DES treatment: (1) a large number of activated protons (H+) from the acidic DES depolymerized the cellulose chain and destroyed the fiber structure; (2) the vigorous hydrogen bonding competitions between fibers and DES (Ch+ and Cl−) facilitated the fiber swelling and reaction efficiency, thus increasing fiber accessibility/reactivity. DES also featured a high recyclability/reusability after serval reuses. Therefore, this work offers a sustainable and effective alternative for production of premium bamboo dissolving pulp. [ABSTRACT FROM AUTHOR]

In this work, bagasse pulp was used to prepare cellulose nanofibrils (CNFs) by enzymatic assisted mechanical treatment. A xylanase pretreatment was applied for varying the hemicellulose content in the pulp fibers, and the contribution of this pretreatment to the post-mechanical treatment was investigated. The results showed that CNFs prepared after xylanase pretreatment exhibited enhanced thermal stability with an increase in crystallinity. However, the overall thermal stability of the CNFs decreased significantly after xylanase was applied directly to the mechanical treated CNFs. The results indicate that the presence of hemicellulose in the fiber could affect the thermal stability of CNFs. The direct application of xylanase to CNFs could affect both the hydrogen bond between the hemicellulose and the cellulose and the covalent bond between the hemicellulose molecules, which partially destroys the internal network structure and reduces of thermal stability of CNFs. [ABSTRACT FROM AUTHOR]

The lignin-derived inhibition on cellulase is the most critical bottleneck that must be addressed when converting lignocellulosic biomass through the sugar-platform process. Herein, a novel modified cellulase with high activity, great stability and excellent lignin-resistant ability was synthesized by chemical modification using hydrophilic and negatively charged polyethylene glycol (PEG) derivatives including HO-PEG-COOH and HOOC-PEG-COOH. Both modifications obviously increased the cellulase activity, with 37% (HO-PEG-COOH modification) and 53% (HOOC-PEG-COOH modification) increase, respectively. In addition, the stabilities of both modified cellulases were significantly enhanced, seeing from their much higher activities at all selected temperatures and pH values. The modification resulted in a movement of tryptophan residues to the exterior of enzyme, allowing the substrate chains to be more easily recruited and thus initiating the hydrolysis. The compactness of secondary structure for enzyme was improved, especially, the α-helix content was increased which requires strong hydrogen bonding to generate it, thus enhancing the stability. High hydrophilicity, negative charge and compactness of enzyme conferred modified cellulase good ability to resist lignin adsorption and destruction, thus improving the enzymatic hydrolysis of corn stover. [Display omitted] • Cellulase activity is significantly improved by up to 52% after chemical modification. • The migration of Trp residues allows the hydrolysis to be more easily initiated. • High compactness gives modified cellulase great stability and low level of damage by lignin. • High hydrophilicity and negative charge of modified cellulase prevent lignin adsorption. • The novel modified cellulase exhibits promising potential in converting corn stover. [ABSTRACT FROM AUTHOR]