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Following the circular bioeconomy concept, this work studies the potential of an industrial wastepaper residue as an alternative raw material for dissolving pulp‐grade production. Prehydrolysis‐kraft cooking (PHK), elemental chlorine‐free (ECF) bleaching, and acid‐washing treatments were applied to achieve that aim. Considering the high lignin and hemicellulose content of the raw material, it was submitted to PHK pulping to enhance its cellulose content by removing those components. This processing resulted in a remarkable increase of 84 % in pulp Fock reactivity (from 45.6 % to 84.1 %). The dissolution extension and time in solvent systems LiCl/DMAc and NMMO/H2O were discussed regarding the pulp physicochemical properties. The dissolving pulp produced under this work showed great potential as raw material for textile applications, particularly highlighting the innovative process developed to improve its solubility. [ABSTRACT FROM AUTHOR]

In this research, we developed an efficient method for the fabrication of amorphous cellulosegraphene oxide composite. Amorphous cellulose (AC) and amorphous cellulose-graphene oxide (ACGO) beads were fabricated via H2SO4 gelatinization using eucalyptus paper as a raw material. The cellulose gel was droplet-extruded into deionized (DI) water and transformed to a solid bead via the water-regeneration process. Small AC and ACGO quasi-sphere beads with diameter of 2 mm were obtained. The semicrystalline eucalyptus cellulose was transformed into amorphous cellulose after the regeneration process. The entrapment of graphene oxide (GO) by the amorphous cellulose was confirmed by scanning electron microscopy (SEM), fourier-transform infrared (FTIR) and raman spectroscopies (Raman). The gelatinization and regeneration processes offered a simple and efficient methodology for AC and ACGO bead fabrication. [ABSTRACT FROM AUTHOR]

Abstract This paper reports on the effect of improved porous characteristics of cellulose on its solubility in DMAc/LiCl. The use of freeze-drying (FD) treatment led to higher surface area and void fraction of volume for high-molecular-weight (HMW) cotton cellulose (DP~5000). Improvement in porous characteristics of cellulose did not change the chemical and crystalline structures of cellulose, as compared to hot-drying (HD) treatment. However, significant improvement in the dissolution of FD-HMW cellulose in DMAc/LiCl was observed under relatively low temperature (80 °C). The relationship between the solubility and the porous characteristics of cellulose was discussed using Stokes-Einstein Equation and effective diffusion coefficient equation. It was concluded that the increase in the diffusion coefficient of the solvent and the improvement in the porous characteristics of cellulose played key roles to enhance the diffusion rate of the solvent through the cellulose molecular network. [ABSTRACT FROM AUTHOR]

A series of SILs containing dicarboxylate anions were synthesized via a solvent-free one-step method. By adjusting the amphiphilicity of the anionic and cationic components within the SILs, the dissolution performance of cellulose can be effectively modulated, enabling it to surpass a 10 wt% dissolution capacity for microcrystalline cellulose. Beyond dissolution, fine-tuning SIL's amphiphilicity could control the network and crystalline structure of obtained regenerated cellulose films in water, enabling the creation of cellulose films with excellent properties. [Display omitted] • Straightforward and efficient SIL preparation via a solvent-free one-step method. • SIL's amphiphilicity precisely controls the dissolution and regeneration of cellulose. • Regulating the amphiphilicity of SILs achieves cellulose dissolution exceeding 10 wt%. • Suitable amphiphilicity of SILs enhances the properties of obtained regenerated cellulose films. The processes of dissolving and regenerating cellulose are crucial for transforming cellulose into products with added value. Due to the cellulose's inherent amphiphilic characteristics, both its dissolution and the physical and mechanical properties of the regenerated materials can vary depending on the amphiphilicity of solvent used. Innovative solvent designs that offer precise manipulation of these processes are key in developing regenerated materials with specific desired properties. Here we show that modifying the amphiphilicity of superbase-based ionic liquids (SILs) with dicarboxylates allows for the control of the solubility, crystal structure and film-forming capability of cellulose. Notably, the solubility of microcrystalline cellulose (MCC) in the optimized SILs can exceed 10 wt% at 95 °C. In addition, regenerated cellulose films (RCFs) with a lower (1–10) crystal plane-oriented structure from SIL solution, using water as coagulation bath, possess not only exceptional mechanical properties (tensile strength: 103.63 MPa, elongation at break: 11.89 %), but also transparency (ca. 90 % under visible light) and flexibility. We anticipate that the tailored amphiphilicity design of SILs in this study offers a promising and effective solution for dissolution, modification, and reconstruction of cellulose materials. [ABSTRACT FROM AUTHOR]

The unique molecular structure of cellulose makes it challenging to dissolve at room temperature (R.T.), and the dissolution mechanism remains unclear. In this study, we employed ZnCl 2 aqueous solution for cellulose dissolution at R.T., proposing a novel four-stage dissolution mechanism. The efficient dissolution of cellulose in ZnCl 2 aqueous solution at R.T. involves four indispensable stages: rapid migration of hydrated Zn2+ ions towards cellulose, sufficient penetration between cellulose sheets, strong interaction with cellulose hydroxyl groups, and effective dispersion of separated cellulose chains. The proposed four-stage dissolution mechanism was validated through theoretical calculations and experimental evidence. The hydrated Zn2+ ions in ZnCl 2 + 3.5H 2 O solvent exhibited ideal migration, penetration, interaction, and dispersion abilities, resulting in efficient cellulose dissolution at R.T. Moreover, only slight degradation of cellulose occurred in ZnCl 2 + 3.5H 2 O at R.T. Consequently, the regenerated cellulose materials obtained from ZnCl 2 + 3.5H 2 O (R.T.) exhibited better mechanical properties. Notably, the solvent recovery rate reached about 95 % based on previous usage during five cycles. The solvent is outstanding for its green, low-cost, efficiency, simplicity, R.T. conditions and recyclability. This work contributes to a better understanding of the cellulose dissolution mechanisms within inorganic salt solvents at R.T., thereby guiding future development efforts towards greener and more efficient cellulosic solvents. A novel room temperature-induced cellulose dissolution mechanism for green ZnCl 2 /H 2 O solvent system was proposed: migration, penetration, interaction, and dispersion. [Display omitted] • The ZnCl 2 + 3.5H 2 O solvent efficiently dissolved cellulose at room temperature. • The dissolving ability of ZnCl 2 /H 2 O was determined by regulating water content. • A novel four-stage strategy to dissolve cellulose at room temperature was proposed. • The ZnCl 2 + 3.5H 2 O solvent presents excellent stability and recyclability. [ABSTRACT FROM AUTHOR]

Cellulose, as the most abundant sustainable resource on earth, can be chemically transformed into a variety of biodegradable materials, which have been proposed as the ideal substitutes for plastic products. The first challenge for the fabrication of cellulose-based functional materials is the successful dissolution of cellulose by solvents. However, most existing cellulose solvents have environmental, economic, and other drawbacks that limit their further industrial applications. Research on developing novel solvent systems with "greener" and "cheaper" properties is needed to meet the challenges. [ABSTRACT FROM AUTHOR]

Low-temperature two-step concentrated H 2 SO 4 was discovered to be a solvent with high cellulose solubility [>300 g/L (17 wt%)], fast cellulose dissolution, high regeneration yield (>0.92 g/g), and cellulose being mouldable during regeneration. The superior performance was enabled by the much better compatibility of cellulose with lower concentrated H 2 SO 4 at low temperature, compared with that of high concentrated H 2 SO 4. The regenerated cellulose was characterized by mostly unchanged composition and highly tunable degree of polymerization (DP). The H 2 SO 4 starting content, cotton fibre temperature, dissolution temperature, regeneration temperature, regeneration bath and storage time were factors determining the DP of regenerated cellulose, which could be equivalent to 4–90 % of the original cotton. These advantages of the solvent enabled versatile application in fabrication of extra strong cellulose hydrogels, manufacture of strong cellulose fibres, preparation of various homogenous composites which would be prepared with much more difficulty by using other solvents, and facile manufacture of cellooligosaccharides. [Display omitted] • Cellulose fast dissolved with no crystal structure in 68 % H2SO4 (≤0 °C). • High cellulose solubility (>300 g/L) was achieved in low-temperature H 2 SO 4. • High cellulose regeneration yield was achieved (as high as 0.97 g/g). • Highly tunable cellulose structure in the low-temperature H2SO4 dissolution process • Cellulose hydrogel, fibre, homogenous composites, and oligosaccharides were prepared. [ABSTRACT FROM AUTHOR]