Cellulose Chains Research Articles

High tensile regenerated cellulose fibers via cyclic freeze-thawing enabled dissolution in phosphoric acid for textile-to-textile recycling of waste cotton fabrics

Recycling of waste cotton fabrics (WCFs) is a desirable solution to address the problems brought up by fast fashion, but it remains challenging due to inherent limitations in preparing stable and spinnable dopes by dissolving high molecular weight cellulose efficiently and cost effectively. Herein, we show that despite the prevailing concerns of cellulose degradation via glycosidic hydrolysis when dissolved in acids, fast and non-destructive direct dissolution of WCFs in aqueous phosphoric acid (a.q. PA) could be realized using a cyclic freeze-thawing procedure, which combined with subsequent adjustment of degree of polymerization (DP) and degassing yielded stable and spinnable dopes. Regenerated cellulose fibers (RCFs) with favorable tensile strength (414.2 ± 14.3 MPa) and flexibility (15.4 ± 1.5 %) could be obtained by carefully adjusting the coagulation conditions to induce oriented and compact packing of the cellulose chains. The method was shown to be conveniently extended to dissolve reactively dyed WCFs, showing great potential as a cheap and green alternative to heavily explored ionic liquids (ILs) and N-methylmorpholine-N-oxide (NMMO)-based systems for textile-to-textile recycling of WCFs.

New reaction pathways for high selectivity synthesis of methyl lactate via SnClx(OH)2-x-catalyzed cellulose conversion in water-containing methanol solution

Catalytic conversion of cellulose into lactic acid (LA) is paramount for the emerging biomass-based chemical industry. With emphasis on the reaction mechanism, the catalytic cellulose conversion to methyl lactate (ML) was systematically investigated in water-containing methanol solution. The role that water plays and catalytic mechanism of the acidic and basic sites were analyzed and discussed. It was found that water played an important role in modulating hydrolysis of SnCl2 to release H+ protons and basic SnClx(OH)2-x species. These basic species are very efficient for the isomerization and [3+3] retro aldol condensation in terminal glucose units of cellulose chain, while H+ protons facilitate the ring-opening of the ends of cellulose chains to trioses rather than hydrolysis of the glucoside bonds to form glucose. Based on advanced characterization techniques including ESI-MS, GPC, FT-IR, XRD, XPS and CP-MAS 13C NMR as well as DFT calculations, two new reaction pathways were disclosed for the first time, which are distinct from the well-known traditional pathway that goes through the formation of glucose. Owing to the exclusion of the formation of glucose during the cellulose conversion, the selectivity towards ML can be greatly enhanced. Under optimal conditions, the total selectivity could reach to 91.5 % with a ML and LA yield of 66.3 %. These findings provide new insights into the catalytic conversion of cellulose into value-added chemicals and help explore effective catalysts.

Efficient cellulose dissolution and derivatization enabled by oxalic/sulfuric acid for high-performance cellulose films as food packaging

The performance of cellulose-based materials is highly dependent on the choice of solvent systems. Exceptionally, cellulose dissolution and derivatization by efficient solvent have been considered as a key factor for large-scale industrial applications of cellulose. However, cellulose dissolution and derivatization often requires harsh reaction conditions, high energy consumption, and complex solubilizing, resulting in environmental impacts and low practical value. Here we address these limitations by using a low-temperature oxalic acid/sulfuric acid solvent to enable cellulose dissolution and derivatization for high-performance cellulose films. The dissolution and derivatization mechanism of the mixed acid is studied, demonstrating that cellulose is firstly socked by oxalic acid, then more hydrogen bonds ionized by sulfuric acid break cellulose chain, and finally the esterification reaction between oxalic acid and cellulose is catalyzed by sulfuric acid. Solutions containing 8 %–10 % cellulose are obtained and can be stored for a long time at −18 °C without significant degradation. Moreover, the cellulose film exhibits a higher tensile strength of up to 66.1 MPa, thermal stability, and degree of polymerization compared to that fabricated by sulfuric acid. These unique advantages provide new paths to utilize renewable resources for alternative food packaging materials at an industrial scale.

Accumulation of Hydrogen Bonds and van der Waals Interactions Determines Force Response between Two Parallel Cellulose Chains: Steered Molecular Dynamics Simulations.

We investigated the response forces between two parallel cellulose chains during the shearing and tearing processes by using steered molecular dynamics simulations. It was found that there are two logarithmic dependencies between response force and pulling speed in shearing processes but only one in tearing, according to Bell's equation by fitting the f-ln v curve. The mechanism is that there are 2-fold interactions determining the force response between two parallel cellulose chains resisting chain separation during a shearing process. Our results indicate that hydrogen bonds dominate the interchain interactions in the fast pull mode (FPM) for shearing, while van der Waals interactions dominate in the slow pull mode (SPM). For tearing, the one-by-one breaking of hydrogen bonds and van der Waals interactions plays a main role.

Effect of glycerol plasticizer on the structure and characteristics of bacterial cellulose-based biocomposite films

Abstract Biocomposite film was successfully produced by combining bacterial cellulose (BC) and sodium alginate (ratio of 80:20) with the addition of glycerol as conventional plasticizer at varied concentration (2, 4, 6% w/w, based on total sample weight) through solution casting method. The influence of glycerol content on structure (by FTIR), mechanical properties, optical properties (by colorimeter and spectrophotometer) and water vapor permeability (WVP, gravimetric method) of BC biocomposite film was investigated. The addition of glycerol disrupts the inter- and intramolecular hydrogen bonds in the cellulose chains, replaced by weaker BC-alginate-glycerol bonds. This resulted a decrease in film density, causing lower tensile strength, lightness, opacity and WVP of BC biocomposite film. An increase in glycerol concentration led to an increase in elongation percentage due to the effect of glycerol plasticization. Film with 4% glycerol exhibited the lowest WVP (5.08x10-13 g/m.s.Pa), highest lightness (L = 73.49), lowest opacity (3.24 Abs/mm) with tensile strength of 19.57 MPa and elongation 8.38%. The addition of glycerol significantly affects the BC biocomposite film properties. The resulting biofilm shows performance equivalent to commercial bioplastic TeloRoll.

In-Depth Understanding of the Effect of the Distribution of Substituents on the Morphology and Physical Properties of Ethylcellulose: Molecular Dynamics Simulations Insights.

Ethylcellulose (EC) is a crucial cellulose derivative with widespread applications, particularly in the pharmaceutical industry, where precise property adjustments through chemical modification are imperative. The degree of substitution (DS) and the localization of substituents along the cellulose chains are pivotal factors in this process. However, the impact of the substituent location within the repeating unit of EC remains unexplored. To address this gap, we conducted molecular dynamics simulations on amorphous EC, comparing randomly and uniformly substituted ethyl groups in the repeating units. This comprehensive study of pairwise interactions revealed significant differences in intramolecular and intermolecular hydrogen-bonding capabilities, depending on whether the hydroxyl groups were substituted at C2, C3, or C6. While our simulations demonstrated that substituent localization in the repeating unit influenced the density, number of hydrogen bonds, and conformations, the DS emerged as the dominant determinant. This insight led us to propose and validate a hypothesis: a straightforward linear function using the properties of uniform models and molar fractions can predict the properties of randomly substituted EC with a given DS. This innovative approach is anticipated to contribute to the selection of cellulose derivatives with desirable properties for the pharmaceutical industry and new applications in other fields.

Hydrolytic-Assisted Fractionation of Textile Waste Containing Cotton and Polyester

Resulting properties of cotton and polyester blends make polycotton the most common fabric in textile industry. Separation technologies are key for the chemical processing of the massive amount of polycotton waste produced worldwide. The very different chemical nature of cellulose and polyethylene terephthalate determines the fractionation strategies to obtain two valuable monomaterial streams. In this work, we propose separation pathways seeking the conversion both polymers. First, polyester was depolymerised into its monomeric units through catalytic alkaline hydrolysis. The combined effect of alkali concentration and the catalyst was analysed to overcome the hydrophobic nature of polyester and optimise its conversion rate minimising the damaged caused to the cellulose chains. Conversion rates up to 80% were reached in a single separation stage with a limited effect of the polymer chain distribution of cellulose which remains a fiber-grade feedstock. Alternatively, cellulose was fully removed by selective dissolution in ionic solvent and subsequent filtration resulting in a spinnable mixture. Finally, enzymatic treatments for the conversion of cellulose into fermentable sugars were studied. Single stage conversions of 65% were achieved after maximizing the enzymatic activity. Structural and spectroscopic analysis showed that crystalline domains of textile-grade cotton limit the enzymatic activity. Optimal fractionation process is, in our view, highly context dependent what conveys to seek a variety of alternatives seeking for chemical processes driven by the ulterior up-cycling of the monomaterial streams

A one-stone-two-birds strategy for cellulose dissolution, regeneration, and functionalization as a photocatalytic composite membrane for wastewater purification

Photocatalytic membranes integrate membrane separation and photocatalysis to deliver an efficient solution for water purification, while the top priority is to exploit simple, efficient, renewable, and low-cost photocatalytic membrane materials. We herein propose a facile one-stone-two-birds strategy to construct a multifunctional regenerated cellulose composite membrane decorated by Prussian blue analogue (ZnPBA) microspheres for wastewater purification. The hypotheses are that: 1) ZnCl2 not only serves as a cellulose solvent for tuning cellulose dissolution and regeneration, but also functions as a precursor for in-situ growth of spherical-like ZnPBA; 2) More homogeneous reactions including coordination and hydrogen bonding among Zn2+, [Fe(CN)6]3− and cellulose chains contribute to a rapid and uniform anchoring of ZnPBA microspheres on the regenerated cellulose fibrils (RCFs). Consequently, the resultant ZnPBA/RCM features a high loading of ZnPBA (65.3 wt%) and exhibits excellent treatment efficiency and reusability in terms of photocatalytic degradation of tetracycline (TC) (90.3 % removal efficiency and 54.3 % of mineralization), oil-water separation efficiency (>97.8 % for varying oils) and antibacterial performance (99.4 % for E. coli and 99.2 % for S. aureus). This work paves a simple and useful way for exploiting cellulose-based functional materials for efficient wastewater purification.

A strategy for introducing biomass naringin molecules into regenerated cellulose fibers: Construction of both low fibrillation tendency and high strength lyocell fibers

Lyocell fiber is regarded as one of the most representative green fibers, which has higher strength than other regenerated cellulose fibers, but is easily fibrillated when produced. Here, we developed a strategy to strengthen lyocell fiber by the strong interaction between the small molecules of biomass and polymeric cellulose chain networks. The green biomass naringin molecules containing phenolic hydroxyl structures are introduced into the solvent (N-methyl morpholine-N-oxide, NMMO) system of producing lyocell fiber, and the rational arrangement of naringin and cellulose molecular chains is precisely controlled through fiber-forming process of dry-jet-wet spinning and wet-drafting. Due to the interaction of strong hydrogen bond between naringin and cellulose molecules, the strength, toughness and Young’s modulus of the obtained composite fibers reached 500.78 ± 33.57 MPa, 28.16 ± 4.65 MJ/m3 and 23.06 ± 1.01 GPa, respectively, which were 86.96 %, 44.86 % and 48.97 % higher than those of pure lyocell fibers. In addition, naringin molecules have two directional (the longitudinal and transverse direction) bonding effects, which not only improves the mechanical performance of the fiber, but also reduces the fibrillation. The simultaneously improvement of mechanical performance and the reduction of fibrillation tendency are unprecedented in related studies, which contributes to the production of better performance lyocell fibers.

Structure elucidation of a multi-modular recombinant endoglucanase, AtGH9C-CBM3A-CBM3B from Acetivibrio thermocellus ATCC 27405 and its substrate binding analysis

Cellulases from GH9 family show endo-, exo- or processive endocellulase activity, but the reason behind the variation is unclear. A GH9 recombinant endoglucanase, AtGH9C-CBM3A-CBM3B from Acetivibrio thermocellus was structurally characterized for conformation, binding and dynamics assessment. Modeled AtGH9C-CBM3A-CBM3B depicted (α/α)6-barrel structure with Asp98, Asp101 and Glu489 acting as catalytic triad. CD results revealed 25.2 % α-helix, 18.4 % β-sheet and rest 56.4 % of random coils, corroborating with predictions from PSIPRED and SOPMA. MD simulation of AtGH9C-CBM3A-CBM3B bound cellotetraose showed structural stability and global compactness with lowered RMSD values (1.5 nm) as compared with only AtGH9C-CBM3A-CBM3B (1.8 nm) for 200 ns. Higher fluctuation in RMSF values in far-positioned CBM3B pointed to its redundancy in substrate binding. Docking studies showed maximum binding with cellotetraose (ΔG = −5.05 kcal/mol), with reduced affinity towards ligands with degree of polymerization (DP) lower (DP < 4) or higher than 4 (DP > 4). Processivity index displayed the enzyme to be processive with loop 3 (342–379 aa) possibly blocking the non-reducing end of cellulose chain, resulting in cellotetraose release. SAXS analysis of AtGH9C-CBM3A-CBM3B at 5 mg/mL displayed monodispersed state with fist-and-elbow shape in solution. Negative zeta potential of −24 mV at 5 mg/mL indicated stability and free from aggregation.

Enhancing plant fiber antibacterial and antiviral performance through synergistic action of amino and sulfonic acid groups

As the most abundant renewable resource, cellulose fibers are potential candidates for use in health-protective clothing. Herein, we demonstrate a novel strategy for preparing cellulose fiber with prominent antibacterial and antiviral performance by the synergistic effect of amino groups and sulfonic acid groups. Specifically, guanylated chitosan oligosaccharide (GCOS) and N-sulfopropyl chitosan oligosaccharide (SCOS) were synthesized and chemically grafted onto cellulose fibers (CFs) to endow the fibers with antibacterial and antiviral properties. Moreover, a compounding strategy was applied to make the fibers with simultaneously high antibacterial and antiviral activity, especially in short contact time. The bacteriostatic rate (against S. aureus: 95.81 %, against E. coli: 92.07 %, 1 h) of the compounded fibers improved substantially when a few GCOS-CFs were mixed with SCOS-CFs; especially, it was much higher than both the individual GCOS-CFs and SCOS-CFs. By contrast, the improvement of the antiviral properties was less dramatic; however, even a few SCOS-CFs was mixed, the antiviral properties increased pronouncedly. Although the electrostatic interaction between SCOS and GCOS can make the SCOS-GCOS mixture lose some extent of antibacterial activity, the long chains of cellulose restrain the electrostatic interaction between sulfonic and amino groups, leading to their synergistic action and eventually superior antibacterial and antiviral effects.

Synthesis, characterization and performance of quaternized cellulose based flocculant derived from office paper waste for dye removal

Abstract The quaternized cellulose derivatives (QCs) were synthesized by reacting extracted cellulose from office paper waste with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) in an aqueous solution of sodium hydroxide (NaOH) – urea. The characterization results by using Fourier-Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicate that the office paper waste properties changed after chemical treatment and the extract product was confirmed cellulose. In addition, the FT-IR and SEM results confirmed the successful introduction of cationic quaternary ammonium groups into the main chain of cellulose. Meanwhile, the XRD results revealed that the crystalline structure was destroyed during etherification reaction. By using synthetic Congo red dye, the flocculation performance of the QCs was evaluated via standard jar test method at different QC dosages, initial Congo red dye concentration and pH values. It was found that the QC10 exhibited a more effective flocculation capability as compared to other synthesized QCs for over a wide pH value. The QC10 performed the best at pH 7, 100 mg/L of Congo red dye concentration and 50 mg/L of QC dosage, with percentage removal of 89.09 %. These findings demonstrated the potential application of QC in dye removal.

BC-g-PAA: Characterization and Establishment of the IPN Hydrogel

A study on the manufacture of bacterial cellulose IPN hydrogel crosslinked poly acrylic acid using the MBA crosslinker. This study aims to characterize and observe the reaction to form bacterial cellulose-based hydrogel IPN. The BC-g-PAA was characterized by the degree of cross-linking, swelling ratio, and FTIR analysis. The results of this study found predictions of the reaction process for the formation of IPN Hydrogel in several process stages, namely 1) The polymerization process of bacterial cellulose chains that form cross-linked networks independently, 2) The process of cross-linking Acrylate monomers with MBA crosslinkers in three steps, i.e. initiation, propagation and termination, 3) Reaction process Formation of IPN network. The results of the characterization test for the degree of crosslinking were 54.55%; Swelling ratio of 1631.25%. FTIR analysis shows that there is a peak that identifies the occurrence of crosslinking

Large-scale spatially explicit analysis of carbon capture at cellulosic biorefineries

The large-scale production of cellulosic biofuels would involve spatially distributed systems including biomass fields, logistics networks and biorefineries. Better understanding of the interactions between landscape-related decisions and the design of biorefineries with carbon capture and storage (CCS) in a supply chain context is needed to enable efficient systems. Here we analyse the cost and greenhouse gas mitigation potential for cellulosic biofuel supply chains in the US Midwest using realistic spatially explicit land availability and crop productivity data and consider fuel conversion technologies with detailed CCS design for their associated CO2 streams. Optimization methods identify trade-offs and design strategies leading to systems with attractive environmental and economic performance. Strategic and operational decisions depend on underlying spatial features and are sensitive to biofuel demand and CCS incentives. US CCS incentives neglect to motivate greenhouse gas mitigation from all supply chain emission sources, which leverage spatial interactions between CCS, electricity prices and the biomass landscape.

Cellulose gelation in aqueous hydroxide solutions by CO2(g): Fact and theory

Understanding how the solvent structure affects the stability of the dissolved state and the following precipitation is important for designing future dissolution-coagulation systems for cellulose processing. In this study, two morpholinium hydroxides with different alkyl chain lengths, namely N,N-dimethylmorpholinium hydroxide (NDMMOH(aq)) and N‑butyl‑N-methyl morpholinium hydroxide (BMMorOH(aq)), were studied and compared with the previously thoroughly investigated cellulose solvent benzyltriemethylammonium hydroxide (Triton B(aq)) which is well-known for its superior ability to stabilize the dissolved state. Cellulose solutions in each solvent were characterized by NMR, flow and frequency sweeps, while cellulose coagulation by CO2(g) was followed by in situ FTIR, pH and temperature measurements. The coagulated systems were characterized by CP/MAS 13C NMR, flow, and frequency sweep measurements. Complementary molecular dynamic (MD) simulations were performed to gain a deeper insight into the observed gelation behavior. The intrinsic viscosity indicated more extended cellulose chains in the solvents with more hydrophobic moieties (Triton B and BMMorOH). Even though the course of coagulation did not show any significant differences during monitoring, both the properties of the obtained gels and the MD simulations indicated differences in formation and properties of the coagulated materials that could be related both to the choice of solvent and coagulant.

Characterization of extracted bio-nano particles from date palm agro-residues

Mechanical downsizing of waste lignocellulosic fibers to small-size particles is a promising way to produce efficient reinforcing elements for bio-composites, both from commercial and environmental perspectives. This study specifically aims to make nano-sized lignocellulosic fillers from date palm agro-residues using a mechanical ball milling technique supplemented with liquid Nitrogen. The researchers aimed to obtain efficient reinforcing elements for bio-composites by fragmenting and downsizing waste lignocellulosic fibers. Several tests were conducted to evaluate and characterize the fillers' properties. The morphological analysis using TEM and FE-SEM showed that the microparticles had irregularly shaped particles with sizes ranging from 0.6 to 0.8 μm for micro-untreated particles and 0.22–0.32 μm for micro-treated particles. The nanoparticles had smaller particle sizes, with nano-untreated particles ranging from 80 to 122 nm and nano-treated particles ranging from 32 to 55 nm. XRD analysis revealed a boost in crystallinity due to the treatment process; (45 %) for micro-treated and (67 %) for nano-treated. TGA analysis indicated that the chemically treated fillers contributed to the improved thermal stability of the samples. Specifically, MT showed the best thermal stability due to increased crystallinity and stronger binding among the cellulose chains than that of NT.

Study of Cellulose Dissolution in ZnO/NaOH/Water Solvent Solution and Its Temperature-Dependent Effect Using Molecular Dynamics Simulation.

Cellulose is a biopolymer with numerous advantages that make it an ecological, economical, and high-performing choice for various applications. To fully exploit the potential of cellulose, it is often necessary to dissolve it, which poses a current challenge. The aqueous zinc oxide/sodium hydroxide (ZnO/NaOH/Water) system is a preferred solvent for its rapid dissolution, non-toxicity, low cost, and environmentally friendly nature. In this context, the behavior of cellulose chains in the aqueous solution of ZnO/NaOH and the impact of temperature on the solubility of this polymer were examined through a molecular dynamics simulation. The analysis of the root means square deviation (RMSD), interaction energy, hydrogen bond curves, and radial distribution function revealed that cellulose is insoluble in the ZnO/NaOH solvent at room temperature (T = 298 K). Decreasing the temperature in the range of 273 K to 268 K led to a geometric deformation of cellulose chains, accompanied by a decrease in the number of interchain hydrogen bonds over the simulation time, thus confirming the solubility of cellulose in this system between T = 273 K and T = 268 K.

Delignification of wood fibers using a eutectic carvacrol–methanesulfonic acid mixture analyses of the structure and fractional distribution of lignin, cellulose, and hemicellulose

AbstractDelignification and fractional pretreatments are essential for valorization of wood biomass in various bioproducts. Herein, lignocellulose wood fibers were exposed to a eutectic mixture (EM) of carvacrol and methanesulfonic acid for different times. The resulting structural and chemical alterations in biomass were explored in terms of the fiber morphology and fractional chemical composition through fiber image analysis, field-emission scanning electron microscopy, high-performance liquid chromatography, and a novel approach based on fluorescence-lifetime imaging microscopy (FLIM). The autofluorescence of the lignocellulose fibers, which was primarily due to lignin with contributions from cellulose and hemicellulose, enabled application of FLIM in lignocellulose compositional analysis in micro-scale. FLIM analysis revealed that EM treatment efficiently removed lignin from the outer fiber layers. Furthermore, the effective EM treatment time was 3 h (with a residual lignin content of ~ 7 wt%), after which defects were observed on the fibers and the cellulose chains started breaking. This degradation was also indicated by a shift of the lifetime spectra toward the fluorescence lifetime of cellulose with increasing treatment time. Overall, our findings provide valuable insights to the response of lignocellulose fibers to EM treatment, contributing to the important goal of wood biomass application in bioproducts.

Preparation of Filter Paper from Bamboo and Investigating the Effect of Additives.

As air pollution escalates, the need for air filters increases. It is better that the filters used be based on natural fibers, such as non-wood fibers, which cause low damage to the environment. However, the short fiber lengths, low apparent densities, and high volumes of non-wood materials can make it challenging to prepare filter paper with the required mechanical and physical properties. In that context, this study focused on utilizing bamboo fibers to fabricate filter paper by employing the anthraquinone soda pulping method. The pulp underwent bleaching and oxidation processes, with the incorporation of cationic starch (CS) and polyvinyl alcohol (PVA) to enhance resistance properties, resulting in the creation of handmade filter papers. The findings revealed that the tear, burst, and tensile strength of filter paper increased with the oxidation and addition of CS and PVA. Air permeability increased with addition of PVA and combination of CS and PVA. FTIR demonstrated the conversion of hydroxyl groups in cellulose chains to carboxyl groups due to oxidation. SEM images illustrated alterations in the fiber structure post-oxidation treatment, with CS reducing pores while PVA and the CS-PVA combination enlarged pore size and enhanced porosity. The BET surface area surface area expanded with oxidation and the addition of the CS-PVA blend, indicating heightened filter paper porosity. Notably, the combined inclusion of CS and PVA not only augmented mechanical strength but also increased porosity while maintaining pore size.

A fresh perspective on dissociation mechanism of cellulose in DMAc/LiCl system based on Li bond theory

In this case, various characterization technologies have been employed to probe dissociation mechanism of cellulose in N,N-dimethylacetamide/lithium chloride (DMAc/LiCl) system. These results indicate that coordination of DMAc ligands to the Li+–Cl− ion pair results in the formation of a series of Lix(DMAc)yClz (x = 1, 2; y = 1, 2, 3, 4; z = 1, 2) complexes. Analysis of interaction between DMAc ligand and Li center indicate that Li bond plays a major role for the formation of these Lix(DMAc)yClz complexes. And the saturation and directionality of Li bond in these Lix(DMAc)yClz complexes are found to be a tetrahedral structure. The hydrogen bonds between two cellulose chains could be broken at the nonreduced end of cellulose molecule via combined effects of basicity of Cl− ion and steric hindrance of [Li (DMAc)4]+ unit. The unique feature of Li bond in Lix(DMAc)yClz complexes is a key factor in determination of the dissociation mechanism.