An effective pathway for textile recycling could be the successful integration of the textile waste into a closed-loop system; however, one of the key challenges is the removal of color from textile waste. In this study, we developed a two-step reductive-oxidative treatment to convert reactive-dyed textile waste into a white feedstock suitable for textile recycling. The process includes a reductive stage using Na2S2O4, followed by oxidative bleaching with H2O2. Colorimetric, mechanical, morphological, polymeric, elemental, and thermal analyses were performed using standard methods to evaluate the characteristics of the color-stripped fabrics. Under optimized conditions, up to 99.3% color stripping was achieved, along with high lightness (L* = 89.1) and whiteness index (WI = 87.6). The average tensile strength retention of 87.2%, maximum weight loss of 3.5%, limited surface fibrillation observed under scanning electron microscopy, and a minimum degree of polymerization of 1404 suggested that only limited cellulose degradation occurred, allowing the treated materials to retain the properties required for subsequent chemical recycling. Bulk and surface elemental analyses further confirmed a significant reduction in nitrogen content and the complete removal of sulfur, demonstrating effective dye removal and the restoration of the fabric to a composition closely resembling that of the undyed material, while the data from X-ray diffraction revealed only minor changes in the crystallinity index, indicating that the polymer structure remained stable. Thermogravimetric analysis likewise indicated that the thermal profile of the fabrics after dye removal was restored to that of the undyed fabric. The excellent redyeability and uniform color uptake of the color-stripped fabrics indicated their promising potential to be reintroduced into circular textile systems through either chemical recycling into new textile products or mechanical recycling via shredding and blending with virgin fibers.

Real-time monitoring provides valuable information for optimizing fiber spinning conditions. This work combines two self-developed devices, a monofilament dry-jet wet spinning system and an optical measuring device. The measuring protocol was validated and applied to capture the evolution of cellulose fibers during the Ioncell® process. Seven representative points were chosen to evaluate changes in diameter, birefringence and the mass transfer between the filament and the coagulation bath. When exiting the spinneret, the filament shows die swell in the air gap where axial strain induces polymer matrix rearrangement, accompanied by a diameter decrease before entering the coagulation bath where the solvent exchange occurs. It relies on the filament surface-to-volume ratio correlating linearly with the fiber diameter. Structurally, birefringence grows initially until the solvent exchange pushes fiber regeneration. After a minor decrease, Δn remains nearly constant. Polymer chain rearrangement occurs primarily in the air gap whose flow-induced birefringence is proportional to draw ratio reaching 1.88 ⋅ 10-3 for DR=11 whereas Δn = 0.26 ⋅ 10-3 for DR=1. As the filament regenerates Δn increases up to 12.7 ⋅ 10-3 before entering a plateau. Characterization of the obtained fibers validates the protocol, reinforcing that process variables leading to a larger flow-oriented polymer chain yield fibers with higher tenacity and lower flexibility.

Development of all-cellulose composites is a promising approach to fabricate functional textiles. Our research presents a proof of concept to incorporate modified cellulose nanofibrils (CNFs) into a regenerated cellulose textile fibers. In this work, CNFs are modified with a thiol-containing silane coupling agent, available to undergo a “click” reaction with additives possessing a terminal alkene or alkyne. Resulting mercapto-CNF (mCNF) was dissolved in ionic liquid along with the dissolving pulp to attain a controlled concentration of the functional groups. Cellulose-mCNF fibers were spun using Ioncell® technology, resulting in fiber that contains a high percentage of regenerated CNF. During this process, the incorporated silane coupling agents did not withstand the dissolution and were not found in the resultant fiber, likely being discarded with the spin bath.

Transforming the utilization of agricultural residues from single-purpose papermaking into high-value biorefinery strategies can unlock their full potential. The industrial valorization of bagasse is currently hampered by the inefficiency in bleaching chemical use and the limitations of alkali recovery out of silica-rich spent liquors. To address these challenges, this study establishes an integrated biorefinery strategy combining an acid hydrolysis stage (A-stage) for reducing usage of bleaching chemicals along with membrane-based fractionation of spent liquor. In the fiberline, incorporating an A-stage prior to elemental chlorine-free (ECF) bleaching selectively removed half of the hexenuronic acid (HexA). This targeted elimination reduced chlorine dioxide (ClO2) consumption by 25% despite an expected compromise in losing viscosity of bleached pulp fiber. Possible hypothetical migration (fate) of silica from its free amorphous silica form (SiO2) at bagasse to primary form of calcium silicate (CaSiO3) at the pulp fiber is discovered. Ultrafiltration utilizing a 0.5 kDa-sized membrane retained a high-molecular-weight lignin-xylan complex in the retentate while allowing the permeation of 72%-recoverable hydroxy acids (enriched with 2-hydroxybutanoic acid and glucoisosaccharinic acid) and alkali from the permeate, opening up the promise of applying a tailored ultrafiltration separation in addressing limitations in alkali recovery for spent liquor fractionation for bagasse mill.

This study presents a biobased dispersion coating formulated from natural wax and lignin nanoparticles providing hydrophobicity, stain resistance, and antimicrobial functionality for natural fiber textiles. Its durability is demonstrated and has potential for applications like workwear and sportswear to safeguard against fluids, stains, and microbes. A techno-economic assessment for commercial-scale production confirmed the coating’s feasibility and scalability, with a minimum selling price of 379 USD/t for an integrated pulp mill and 389 USD/t for a standalone plant. Despite requiring a higher application volume (3.3 L/m2) than commercial products, the coating remains cost-competitive, with carnauba wax identified as the main cost driver (81 % of variable costs). One-time recycling of coated cotton textiles via the Ioncell® showed properties consistent with the original material, validating the coating’s recyclability potential. Overall, this coating enhances natural fibers performance, is economically competitive, reduces reliance on synthetic materials, and supports the development of high-performance, environmentally friendly textiles.

Old Corrugated Containerboard (OCC) pulp is an abundant source of recovered lignocellulosic material. However, its morphological and chemical heterogeneity presents challenges for upgrading. This study investigates the integration of fiber fractionation followed by oxygen delignification to increase OCC homogeneity by enhancing cellulose content. The pretreated OCC was dissolved in 1,5-diazabicyclonon-5-enium acetate, or [DBNH][OAc], to assess its potential wet spinnability based on temperature dependence and rheological behavior. Fractionation into short- and long-fiber fractions was accomplished using a Pulmac Masterscreen with fine slots of 381 or 152 μm. Fractionation effectively removed non-cellulosic components, reducing ash, fines, and hemicellulose content, while also enhancing the efficiency of subsequent oxygen delignification. The fractionated OCC samples were oxygen delignified using sodium hydroxide charges of 6 and 8%. The oxygen-delignified OCC long-fiber fraction retained higher intrinsic and cellulose-corrected viscosity and yield while achieving a greater degree of delignification and ash reduction relative to the corresponding short-fiber fraction obtained from the same screen. This remained true for the high-yield OCC sample obtained from fiber fractionation using the larger slotted screen. Increasing the NaOH charge from 6 to 8% reduced pulp intrinsic and cellulose-corrected viscosity sufficiently to produce dopes with negligible filtration complications and a storage-to-loss modulus crossover frequency (ωc) near 65–75 °C, within the practical temperature range for wet-spinning [DBNH][OAc] dopes. These results indicate that the combination of mechanical fiber fractionation and oxygen delignification is sufficient to achieve a workable dope for [DBNH][OAc] dissolution and subsequent dry-jet wet spinning of OCC.

Dyes are one of the main obstacles for sustainable recycling and developing an effective dye removal technique is essential to promote textile circularity. In this study, a two-step color stripping treatment is proposed to address the challenge of removing covalently bonded reactive dyes from the cellulose structure. Four different colored cotton fabrics (i.e., green, gray, black and navy) were subjected to a two-step stripping process, involving initial treatment in a hot alkaline sodium hydroxide (NaOH), followed by sodium chlorite (NaClO2) treatment under acidic conditions. Key process parameters influencing the color stripping process such as chemical concentration, temperature and treatment duration were systematically studied and optimized. The color stripping was achieved of 99%, with Lightness (L*) and Whiteness Index (WI) values above 85 and 80, respectively, for all dyed fabrics at optimized conditions. The physicomechanical properties of the color stripped fabrics such as tensile strength and weight loss were found to be 12% and 4%, respectively. Moreover, color stripped fabrics showed 4-6% increase in crystallinity index. In addition, elemental analysis confirmed the complete removal of reactive dyes from treated fabrics, as no sulfur was detected after the treatment. Color stripped fabrics also showed sharper, more stable thermal degradation with less residue, indicating effective dye removal. Furthermore, the reusability of stripping filtrate was investigated up to 3 cycles to assess color stripping performance.

The sustainable recycling of indigo-dyed denim waste remains a major challenge due to the chemical stability and strong fiber affinity. In this study, a closed-loop process for the recycling of indigo-dyed denim waste is developed using dimethyl sulfoxide (DMSO) as a recyclable solvent for color stripping and dye recovery. The influence of solvent composition revealed that 100% DMSO, achieved superior indigo extraction compared to aqueous DMSO systems, achieving colour removal efficiencies of up to 98%. Key process parameters, including treatment time, temperature, and material-to-liquor ratio, were optimized to maximize stripping efficiency. Mechanical characterisation revealed excellent preservation of the cellulose substrate, with tensile strength retention of approximately 98%. The stripped denim exhibited high lightness values (L* > 81), making it potentially a good white feedstock for further recycling or re-dyeing. The recovered DMSO was successfully reused for at least five consecutive stripping cycles without a noticeable loss of performance, demonstrating excellent solvent recyclability. This work provides a potential approach for the closed-loop recycling of indigo-dyed denim waste, supporting circular economy principles and contributing to the development of more sustainable textile recycling processes.

ABSTRACT Keratin‐based textile waste represents an underutilized protein‐rich feedstock, but its conversion into regenerated fibers remains challenging because of its low mechanical strength, poor spinnability, and limited compatibility with other biopolymers. In this work, we applied dry‐jet wet spinning to produce cellulose/keratin hybrid fibers using keratin extracted from textile waste. During extraction, keratin was separated into two fractions, and their chemical composition, secondary structure, and molecular weight were thoroughly analyzed to understand their differences in fiber formation. Hybrid fiber with a cellulose/keratin ratio of 70/30 was continuously produced from the high‐molecular weight keratin fraction using multi‐filament spinning, achieving a linear density of 1.2 dtex (corresponding diameter of 11 µm) and tenacity of 35–40 cN/tex (corresponding tensile strength of ca. 480–560 MPa). More interestingly, the fibers retain their mechanical strength in a wet state, which is rarely achieved for polysaccharide and protein‐based fibers. Additionally, the hybrid fibers exhibit higher hydrophobicity and lower fibrillation tendency compared to pure cellulose fibers. This remarkable approach demonstrates a dual advantage by valorizing keratin waste into valuable resources while simultaneously enabling the tailored tuning of cellulose fiber properties.

Using the Ioncell process, the recycling of low DP textile waste via four case studies, white, blue, and black viscose and white modal fibers, was investigated. The most common man-made cellulose fiber (MMCF) is viscose, a low DP material made of plant-based cellulose, and it accounts for less than 6% of the total amount of textile fibers. Modal, a high-wet modulus viscose fiber, is made by a similar process and presents increased mechanical properties, making it a more durable fiber. Within manufacturing processes, the cellulose polymer is weakened and degraded to an extent that complicates recyclability through conventional methods. The Ioncell technology, a Lyocell-type process developed for the sustainable production of MMCFs, provides the opportunity to repurpose resources from various lignocellulosic waste materials through fiber-to-fiber recycling to create a circular economy. Moreover, the resulting fibers are often stronger than the original fibers, providing textiles of higher quality. Herein, we present the potential of the Ioncell technology for the recycling of low DP textile waste materials. The fibers exhibit exceptional properties, with tenacities up to 1.9 times higher in the dry state compared with their original materials. The fibers were turned into yarn and further used to produce small demonstrators.

The utilization of hemicellulose in fiber production offers a sustainable route for textiles by transforming an otherwise wasted component of wood biomass into value-added material. The high hemicellulose content in these fibers poses challenges for alkaline wet processing, particularly during dyeing with reactive dyes. This study provides a systematic evaluation of how different alkaline conditions influence both the structural stability and dyeability of hemicellulose-rich (HR-Cell) fibers, addressing a knowledge gap in the processing of next-generation biobased cellulosic fibers. We investigate the dyeability and structural stability of HR-Cell fibers under sodium hydroxide (NaOH, 5-10 g/L) and sodium carbonate (Na2CO3, 5-20 g/L) treatments. Comprehensive characterization of HR-Cell fibers, including carbohydrate analysis, molar mass distribution, intrinsic viscosity, degree of polymerization, and crystallinity, showed that NaOH at 10 g/L led to hemicellulose degradation and cellulose depolymerization, whereas Na2CO3 preserved hemicellulose even at elevated concentrations. Dyeing experiments using C.I. Reactive Red 141 and C.I. Reactive Yellow 6 revealed that HR-Cell fibers consistently exhibited higher dye exhaustion, fixation, and color strength compared to cotton, viscose, and Lyocell fibers. The most favorable dyeing results were achieved with 15 g/L Na2CO3, which offered optimal conditions for activating fiber hydroxy groups, minimizing dye hydrolysis, and preserving hemicellulose in the fibers. Colorfastness tests confirmed very good to excellent resistance to washing, rubbing, and light across all samples and conditions.

Developing novel and sustainable processes for the production of bioplastics is crucial to addressing and mitigating the environmental challenges caused by the overconsumption of synthetic plastics. The old-fashioned linear "make-take-waste" consumption models are not environmentally sustainable and need to be transformed to circular systems to preserve natural resources. Therefore, in this study, we successfully recycled regenerated cellulose films into films and textile fibers via the Ioncell process. Films produced from dissolving pulp-ionic liquid (IL) solutions (cycle 0) were redissolved in ionic liquid to form recycled films and fibers within cycle 1. This process was repeated to showcase the recyclability of the cellulose within 2 recycling cycles. In both cycles, thin and highly transparent films have been produced that maintained the strength of the original films but improved the elongation at break (230-235 MPa, 10-13%). The fibers exhibit tenacities and elongations at break comparable to standard Ioncell fibers from virgin pulp (51.3-53.7 cN/tex, 9.2-11.6%). Additionally, a demonstration fabric was knitted from fibers of cycle 1. Overall, the results display the recyclability of the cellulosic films into high-quality products without any loss of quality.

Carbon fibre reinforced composites are used to provide high-strength light-weight materials that are sought after in mobility applications to reduce weight and consequently fuel or energy consumption of the transportation vehicle. Cost and environmental considerations have resurged research on biobased precursors for carbon fibres (CFs) with cellulose being one of the most prominent examples. In this study we shed light on the purity requirements of the cellulose substrate. Thus far, most reports on lignocellulose-based CFs implement highly refined dissolving-grade pulp. To reduce the cost of the precursor fibres and their environmental footprint even further, less refined cellulose sources are desirable. The role of xylan on the properties of the precursor fibres and the carbonization behaviour of holocellulosic precursor fibres were studied. It was found that natively present hemicelluloses in paper-grade kraft pulp can be incorporated homogeneously into the cellulose matrix without impairing the fibre properties, and even showing a beneficial effect on the final carbon yield.

Elastane detection is important for textile recycling as elastane fibers can hamper mechanical and chemical fiber recycling. Here, we report the use of near-infrared imaging spectroscopy and class modelling to detect 2-6% elastane in consumer cotton fabrics to provide alternatives to current detection methods, which are invasive and time-consuming. Our method automatically identified outlier fabrics and measurements with class-specific clustering and showed higher classification accuracies by averaging across individual pixel spectra to reduce sampling uncertainty. The final classification results showed median test set true positive and true negative rates of 89-97% based on randomized resampling. Class modelling offers clear benefits compared to commonly used discriminant classifiers as it allows modelling new classes using only a set of target samples without requiring representative training objects from all the other classes. Overall, these results open the possibility for fast non-invasive detection of small amounts of elastane in cotton, taking us a step closer to a circular economy of textiles.

Enhancing thermal comfort in textiles can contribute to improved user well-being, both in wearable technology and everyday clothing. This study introduces thermoregulation properties by embedding a phase change material (PCM) into regenerated man-made cellulose fibers via the Ioncell® technology. Calorimetric analysis revealed that the incorporation of myristic acid as PCM enables the fibers to absorb and release thermal energy, providing dynamic thermal regulation in response to temperature changes. Specifically, the PCM-fiber containing 50% (w/w) myristic acid demonstrated a phase change melting enthalpy of 73 J g-1, with a melting temperature of 54 °C. The melting enthalpy remained largely stable even after 100 thermal cycling tests, highlighting the excellent durability of the PCM-incorporated textiles. Furthermore, the resulting thermoregulating textile was treated with a hydrophobic coating composed of octadecenyl succinic anhydride, resulting in an average water contact angle of 75°, after post-washing, demonstrating good water repellency. The developed fabric combines thermal regulation with water repellency through eco-friendly processes, offering a promising alternative to conventional functional textiles.

A semi-continuous and industrial-like process to produce regenerated cellulose films, based on the Ioncell (R) technology, is demonstrated. The demand for commercial films, mainly fossil-based, is immense and expected to triple by 2060. This overconsumption leads to drawbacks like fossil reserves depletion and environmental pollution. Therefore, finding sustainable alternative processes compatible with existing industrial operations to produce films from renewable materials like cellulose is crucial. The films herein presented are generated by extruding a cellulose-ionic liquid solution through a distribution plate (DP) and slit nozzle into an aqueous coagulation bath, via an air gap. This study evaluates how different DPs and slit geometries affect the extrusion process and the film properties. Moreover, an automated continuous washing and drying system has been successfully implemented. The produced films are thin (13-17 mu m), homogeneous, highly transparent (89-91%) and strong. The use of DPs resulted in very strong films (242 MPa, 10% elongation at break) but led to extrusion instabilities. Trials without any DP were stable, with films showcasing tensile strengths of 226 MPa and 9% elongation at break. Additionally, a numerical simulation was performed to understand the effects of the DPs and spinnerets' geometry on the dope flow.

Vast environmental impacts from the textile sector have created needs for various circularity practices like sustainable recycling. However, one of the main causes hindering efficient recycling of textile waste is the presence of chemical residues as they are often unwanted in the recycled material and removing them requires additional treatment. One example of a challenging textile waste flow is workwear that is impregnated with sturdy chemical finishes. In this article, we study how a flame retardant chemical finish in workwear affects the environmental efficiency of recycling. Through life cycle assessment, we evaluate the environmental impacts of chemically recycling the textile in scenarios where the chemical is either retained or removed from the material. These recycling scenarios are compared against a scenario of energy recovery through textile waste incineration. According to the results, the removal scenario causes the highest environmental burden, even surpassing the impacts of energy recovery. Recycling the material without chemical removal is the preferred option from an environmental viewpoint. However, due to technology immaturity and speculative substitution assumptions, the uncertainty of the results is high. The results demonstrate the importance of assessing recycling impacts before adoption and highlight the need for designing the products with less permanent chemicals. They also underline the potential of closed loop recycling, which, however, can be challenging to implement in practice.

Recent research shows increased interest in periodate oxidation of cellulose combined with subsequent derivatization to broaden the applications of cellulosic materials. This study attempts to apply this modification strategy to alter the properties of man-made cellulosic fibers (MMCF). Specifically, we investigated whether the introduction of soft segments through cleavage of the C2/C3 bond would result in an increased flexibility of the fibers. Dialdehyde cellulose (DAC) moieties were introduced to cotton up to a degree of oxidation (DO) of 15