Chitosan-Based Composites for Sustainable Textile Production: Applications Across the Lifecycle

Abstract

The fashion and textile industry (FTI) is a significant contributor to greenhouse gas emissions, resource consumption, and waste generation, necessitating sustainable alternatives. Chitosan, a biodegradable and renewable biopolymer, has shown potential in reducing environmental impact throughout the textile lifecycle. However, existing studies often focus on isolated applications rather than its broader role in industrial sustainability. This review synthesises findings from 142 academic studies to assess chitosan’s applications in textile production, dyeing, finishing, and waste management, emphasising its impact on energy efficiency, carbon reduction, and resource circularity. Chitosan’s biodegradability, antimicrobial properties, and affinity for sustainable dyeing offer a viable alternative to synthetic materials while also enhancing wastewater treatment and eco-friendly finishing techniques. By evaluating its contributions to sustainable manufacturing, this review highlights its potential in supporting decarbonisation and circular economy transitions within the textile sector, while also identifying challenges for future research.

1. Introduction

The fashion and textile industry (FTI) substantially contributes to global greenhouse gas emissions, resource depletion, and environmental pollution, playing a significant role in accelerating climate change [1,2,3,4,5,6]. According to the European Environment Agency, the production and consumption of apparel, footwear, and household textiles rank fifth in terms of greenhouse gas emissions [7]. Among these, the apparel sector is particularly concerning, as it is recognised as one of the most environmentally damaging industries [8,9,10,11,12]. The emergence of the “fast fashion” model has further exacerbated this issue, characterised by intensive resource consumption, short product lifecycles, and significant waste generation [7,13,14,15,16,17,18,19]. As a result, integrating sustainability into textile production and consumption has become an urgent necessity [1,14,20,21,22]. Despite the increasing awareness of sustainability challenges, the textile industry continues to face considerable environmental burdens across its entire lifecycle, including pollution, inefficient resource utilisation, and waste accumulation [9,11,23,24,25,26,27,28,29]. Key stages such as raw material sourcing [9,13,30], fabric dyeing and finishing [31,32,33], and end-of-life waste management [34,35,36] present critical challenges that require targeted sustainable solutions [9,37].

Among the various approaches aimed at improving sustainability in the FTI, biotechnology has gained considerable attention for its potential to mitigate pollution and enhance resource efficiency [38,39,40,41]. Chitosan, a biopolymer sourced from chitin, has drawn increasing interest for its biodegradability, broad-spectrum antimicrobial effects, and diverse functional applications [42,43,44,45]. It is derived from chitin, the second most abundant biopolymer after cellulose, which is found in the exoskeletons of crustaceans and insects, as well as in fungal cell walls. Structurally, chitin is a linear homopolymer composed of N-acetylglucosamine units and exists in three polymorphic forms: α-, β-, and γ-chitin. Through partial deacetylation—a process that removes acetyl groups—chitin is converted into chitosan, a copolymer consisting of D-glucosamine and N-acetylglucosamine (Figure 1). This reaction replaces acetylamino groups with amino groups [43]. It has been applied in multiple textile processes, including fibre modification, dyeing, finishing, and wastewater treatment, where it serves as a viable alternative to synthetic chemicals [46,47,48,49,50]. Chitosan-based treatments have demonstrated the ability to improve dye fixation, enhance fabric durability, and contribute to eco-friendly finishing processes, offering a sustainable alternative to petroleum-derived chemicals [47,48,50]. Furthermore, its use in functional textiles supports the development of moisture-retentive, UV-resistant, and antibacterial fabrics, aligning with sustainability-driven textile innovations [51,52,53].

A key environmental issue currently facing the textile sector is water pollution caused by the discharge of synthetic dyes, heavy metals, and chemical residues from dyeing and finishing processes. Chitosan has been extensively studied for wastewater treatment applications, where it functions as a natural adsorbent capable of removing toxic dyes, heavy metals, and organic pollutants, thereby improving effluent quality and reducing sludge generation [54,55,56,57,58,59]. Its cost-effectiveness, biodegradability, and adsorption efficiency make it a compelling candidate for sustainable water management in textile manufacturing [58,59,60].

Although chitosan’s effectiveness in individual textile applications is well documented, most studies have focused on isolated aspects such as dyeing, finishing, or wastewater treatment, without addressing its potential contributions throughout the entire textile lifecycle. Although previous studies have explored chitosan’s functionality in various textile applications, there is still a lack of integrated reviews that examine its contributions across multiple stages of textile manufacturing and waste management [61,62]. This review seeks to address this gap by focusing on selected stages within the textile lifecycle where chitosan-based technologies have demonstrated the most relevance to sustainability.

This paper aims to systematically evaluate the applications of chitosan-based materials in textiles, with a focus on fibre innovation, eco-friendly dyeing and finishing, and sustainable wastewater management. By synthesising existing research, technological advancements, and environmental benefits, this study explores chitosan’s potential to support decarbonisation, circular economy models, and long-term sustainability in textile manufacturing.

To prepare this review, a comprehensive literature search was conducted using authoritative academic databases, including Web of Science, Scopus, and Google Scholar, covering publications from 1999 to 2024. No strict time limitations were imposed, in order to capture both foundational studies and the most recent advancements over the past decade. The search was performed using keyword combinations such as “chitosan”, “textile industry”, “fibre production”, “sustainable dyeing”, “functional finishing”, “textile wastewater treatment”, “biopolymer”, and “circular economy”. This study adopts a narrative review approach rather than a formal systematic review protocol, focusing on research directly relevant to the application of chitosan in the textile field. A total of over 140 peer-reviewed articles, review papers, and relevant conference proceedings were ultimately included, spanning fields such as textile engineering, materials science, and environmental science.

During the process of sorting and analysing the literature, a life-cycle perspective was applied to structure the discussion around key phases including fibre production, dyeing processes, functional finishing, and waste management (particularly wastewater treatment). Each section synthesises and classifies relevant studies according to their role in these stages, thereby building a systematic framework for examining chitosan’s contribution across the textile lifecycle.

2. Production of Chitosan-Based Textile Materials

Chitosan is a natural polymer derived from chitin, which is widely found in crustaceans such as oysters, aphids, and shells. It is the second most abundant biopolymer in nature after cellulose [63,64,65]. Due to its unique physicochemical properties including biocompatibility, non-toxicity, biodegradability, and antimicrobial activity chitosan has garnered significant attention in the textile industry [47,66,67,68,69,70,71,72,73]. It has been extensively explored for applications in various industrial fields, including biomedicine [74,75,76] and the food industry [43,77,78,79,80]. In particular, chitosan has emerged as a promising raw material for the development of eco-friendly textile fibres, offering potential solutions to environmental challenges in the textile sector [8,47,81].

As interest grows in textiles that combine functionality with environmental sustainability [82,83,84,85,86,87], natural polymers such as chitosan have attracted considerable interest in textile research [46,47,82]. Chitosan is regarded as a sustainable material with renewability, biodegradability, and excellent functional properties, making it a strong candidate for textile applications [62,74,88,89,90]. Studies indicate that chitosan can be processed into fibres or blended with other natural or synthetic fibres to enhance mechanical performance and functionality [46,62,82,91]. This section explores the preparation methods, structural properties, and applications of chitosan-based textile materials in fibre production.

2.1. Fibre Morphology and Spinning Techniques of Chitosan-Based Materials

Chitosan-based textile materials primarily include chitosan fibres, yarns, and fabrics [92,93]. The two most commonly used techniques for producing chitosan fibres are wet spinning [47,94,95,96] and electrospinning [46,47]. The fundamental properties of chitosan fibres, including fibre length, fineness, surface morphology, cross-sectional shape, and mechanical strength, significantly influence their spinnability and subsequent applications (see Figure 2).

Different spinning processes or endowing methods result in variations in fibre morphology. Studies have shown that cross-sectional shapes of chitosan fibres can be round, oval, polygonal, or irregular, depending on the spinning process used. Some fibres, such as samples I and J, exhibit smooth surfaces, while others, exemplified by samples K, M, D, and E, display grooved structures (see Figure 2). These morphological differences affect fibre spinnability, mechanical behaviour, and fabric performance [97].

2.2. Mechanical Properties and Structural Characteristics of Chitosan Fibres

The structural characteristics of chitosan-based fibres are pivotal to determining their appropriateness for textile use. Two primary factors affecting fibre behaviour are their degree of deacetylation level (DD) and molecular weight (Mw), both of which affect the mechanical strength and processing behaviour of chitosan fibres [92,97,98]. Measurements reveal that chitosan fibres exhibit tensile strengths ranging from 1.40 cN/tex to 1.90 cN/tex and elongation levels from 10.38% to 18.17%. These values suggest that the fibres possess commendable mechanical performance. Among the tested specimens, sample E recorded the greatest tensile strength, whereas sample I displayed the lowest—a difference that may be linked to their respective highest and lowest degree of deacetylation (DD) [97]. Additionally, higher molecular weight chitosan contributes to greater fibre tensile strength, thereby improving its stability and performance in textile applications [97].

Surface morphology also plays a critical role in fibre performance. Smooth-surfaced fibres generally experience lower frictional resistance during processing, while grooved fibres exhibit enhanced dye adsorption and finishing properties [97].

2.3. Antibacterial Properties of Chitosan-Based Fibres

One of the most remarkable advantages of chitosan fibres is their inherent antimicrobial activity, which supports their application in healthcare fabrics, activewear, and performance textiles [92,99,100,101]. Research evidence indicates that their antibacterial efficacy is influenced by both the degree of deacetylation (DD) and molecular weight (Mw). A higher DD introduces more positively charged amino groups, enhancing interactions with bacterial membranes and thereby improving the antimicrobial response [97].

The experiments demonstrated that variations in the degree of deacetylation (DD) and molecular weight (Mw) of chitosan fibres led to differing levels of inhibition against S. aureus, E. coli, and C. albicans (Figure 3 and Figure 4) [97]. When the DD levels are similar, the antibacterial effect varies with Mw. For example, the inhibition rates of Staphylococcus aureus for samples I, K, L, and M initially increased with increasing molecular weight, but then decreased at higher molecular weight levels. By comparison, the inhibition rate against Escherichia coli continued to decrease with increasing molecular weight [97].

In addition to pure chitosan fibres, chitosan-based hybrid fibres also exhibit significant antimicrobial properties while enhancing various physical properties of the fibres [92,102,103]. Blending is a common technique in textile production, involving the combination of chitosan with non-reactive fibres either prior to or during spinning to create hybrid yarns. This blending process improves the various physical properties of the chitosan fibres, such as durability [104,105], tensile strength [106], smoothness [103,106], and moisture absorption, while further enhancing the antibacterial activity [53,107,108]. Studies have shown that cotton fibres treated with a chitosan–sericin complex have excellent moisture absorption, water vapour permeability, and air permeability. Figure 5 shows scanning electron microscope (SEM) images comparing untreated fibres, chitosan-treated fibres, sericin-treated fibres, and chitosan–sericin complex-treated fibres. Compared to the untreated fibres, the treated fibres have a less smooth surface, with the granular material forming surface irregularities during the finishing process. These surface changes indicate successful adhesion of the finishing agent, as the untreated fibres originally had a uniform and smooth texture. The rough surface increases the surface area, which helps to improve functionalities such as antimicrobial activity, UV protection, oxidation resistance, and enhanced wash durability. The antimicrobial properties are particularly significant. As shown in Figure 6, antibacterial activity tests using a sericin extract and a chitosan solution showed that chitosan has a stronger antibacterial effect. In addition, qualitative bacteriostatic circle tests were carried out on untreated control samples, chitosan-treated samples, sericin-treated samples, and chitosan–sericin co-treated samples. As shown in Figure 7, the chitosan-treated fabric was always superior to the sericin-treated fabric in terms of antibacterial effect (Figure 7b). In addition, the chitosan–sericin composite treatment has a synergistic effect, which forms a larger inhibition zone and markedly lowers bacterial counts relative to treatment with sericin alone (Figure 7c) [107].

The wash durability test further confirmed that the chitosan–sericin treated cotton fibres have long-lasting antibacterial properties. After treatment with 5 mg/mL chitosan and 5 mg/mL sericin, the bacterial reduction rate can reach 78%. Even after 10 washes, the fabric still maintained 60–70% of its antibacterial efficacy, highlighting the stability and durability of the antibacterial properties [107].

The proportion of chitin in the mixed fibre and the molecular weight (Mw) also significantly affect the antibacterial activity. Studies have shown that the optimal chitin mixing ratio is about 5–10%. Concentrations exceeding 10% do not significantly improve antibacterial properties [92]. A well-known example of blending to produce antimicrobial fibres is the development of a superfine chitosan powder (particle size of about 5 μm) by Fuji Textiles Co. Ltd. in Japan. This stable chitosan powder was then incorporated into a viscose solution to produce blended chitosan fibres with enhanced antimicrobial properties [109].

3. Application of Chitosan in Textile Dyeing

Extensive research has explored the use of chitosan as a dyeing auxiliary for natural and synthetic fibres in textile processing. In contrast to traditional dyeing techniques, the use of chitosan in salt-free dyeing offers several advantages, including reducing the need for toxic salts, improving dye fixation, minimising dye hydrolysis, and lowering water consumption, which contributes to reducing overall processing costs [110,111]. Due to its abundance of amino groups, chitosan offers extra interaction sites for anionic dyes, including reactive, acid, and direct types. Through electrostatic interactions and van der Waals forces, these dyes are more effectively adsorbed onto fibres and fabrics. As a result, chitosan treatment enhances key dyeing properties, including the affinity of textiles for anionic dyes, colour strength, and dye fastness.

3.1. Enhancement of Colour Strength

Research findings indicate that applying chitosan enhances dye absorption and intensifies colour yield in textile materials. When cotton fabrics are treated with chitosan before dyeing, they exhibit higher dye absorption, as reflected in increased K/S values compared to untreated fabrics [112]. Experiments conducted with CI Reactive Red and CI Reactive Yellow dyes have shown that chitosan treatment enhances dyeing performance in a concentration-dependent manner. However, when the chitosan concentration exceeded 2%, excess chitosan molecules accumulated on the fibre surface, reducing effective dye-binding sites and resulting in a decline in colour yield. The article suggests that the enhancement of colour intensity in cotton fabrics treated with chitosan primarily stems from the formation of ionic bonds between chitosan’s cationic groups and the anionic groups of reactive dye molecules. Additionally, the chitosan treatment cationised the cotton fibre surface, increasing available binding sites and enhancing dye adsorption through electrostatic interactions. Moreover, chitosan forms a thin physical film on the fibre surface, which reduces dye hydrolysis and strengthens dye–fibre bonding. The inhibitory effect of excessive chitosan was confirmed in concentration-dependent experiments, as reflected in the observed increase and subsequent decrease in K/S values [112]. Studies have found that treating cotton fabrics with 15 g/L of chitosan at a curing temperature of 130 °C significantly increases carmine dye adsorption. Longer dyeing times further enhance dye uptake. Higher dyeing temperatures also improve dye adsorption [113].

3.2. Improvement of Dye Fastness

The colour fastness of dyed fabrics plays a vital role in assessing their overall performance. Research has shown that the use of chitosan improves the wash fastness of dyed materials [112]. Compared to untreated samples, cotton fabrics treated with chitosan consistently show improved resistance to washing. The effect of chitosan treatment on fastness is similar for CI Reactive Red and CI Reactive Yellow dyes. The better results of chitosan treatment as compared to the control experiments were attributed to the application of chitosan to cationise the surface of the cellulosic fabrics and the ionic interactions between the cationic groups of chitosan and the anionic groups of the dyes produced strong bonds, which led to better colour fastness properties of the dyed fabrics [112].

Regarding colour fastness, chitosan-treated fabrics exhibited comprehensive improvements. Washing fastness ratings improved from Grade 4 (control) to Grade 4.5, dry rubbing fastness reached Grade 4.5, and wet rubbing fastness increased from Grade 3.5 to Grade 4.0. However, high chitosan concentrations slightly reduced wet rubbing fastness, while light fastness maintained the highest rating (Grade 5) under all conditions. These results demonstrate that a chitosan concentration of 1.5% to 2% effectively balances dye depth and fastness performance while avoiding the negative effects of excessive treatment [112].

4. Application of Chitosan in Textile Finishing

Chitosan exhibits significant potential in textile finishing due to its biocompatibility, antibacterial properties, biodegradability, and chemical tunability [90,100,114]. The literature highlights chitosan’s applicability in textile finishing through a range of techniques, including nanoparticle coatings [81,100], hydrogel treatments [75,99,115], microencapsulation [83,84], and surface coating methods [116,117]. These approaches endow textiles with enhanced functionalities such as ultraviolet (UV) protection, thermal radiation shielding, antioxidation, and water resistance with antimicrobial activity [84,107,118,119]. This chapter explores the functional finishing technologies based on chitosan, integrating relevant research findings to examine its role in improving textile performance and sustainability.

4.1. Ultraviolet Protection

Ultraviolet (UV) radiation can cause fabric degradation, fading, and potential harm to human health. Therefore, improving the UV protection properties of textiles has become a key focus in functional textile research [84]. Chitosan, as an adhesion-promoting material, can be combined with UV-blocking agents such as zinc oxide (ZnO) to enhance the UV shielding capability of fabrics [84].

A study employed an ultrasonic-assisted method to incorporate ZnO into chitosan nanorods, which were subsequently used on cotton textiles through a pad–dry–cure process. The results demonstrated that this composite material significantly enhanced the UV protection of textiles while maintaining excellent antibacterial properties [120]. Another study developed a chitosan–curcumin (CSN-CRN) polyurethane aqueous dispersion (CSN-CRN APUDs) for fabric finishing. The treated textiles exhibited superior UV [121] protection factors (UPF) and reduced UV transmittance compared to untreated fabrics [121]. Chitosan contains N-acetylglucosamine and glucosamine groups that contribute to UV absorption, while the phenolic groups in curcumin also exhibit strong UV absorption properties [50,122]. The synergistic effect of these two components results in varying levels of UV protection depending on the concentration ratios of chitosan and curcumin dispersions [103].

4.2. Thermal Regulation in Textiles

Chitosan-based composite materials can regulate temperature by reflecting solar radiation and enhancing infrared emissivity. A study fabricated chitosan–SiO₂ composite fibres via wet spinning, which were subsequently woven into textiles using a commercial weaving machine (Figure 8) [51]. According to the article, Figure 9a shows a digital photograph of the rooftop experimental setup for measuring radiative cooling under sunlight irradiation in Zhenjiang, China; Figure 9b records the 24 h temperature in Zhenjiang, China, on a sunny day (from 09:00 on 7 June 2023 to 09:00 on 8 June 2023), displaying real-time solar irradiance (Isolar) and temperature variations of skin simulators under different experimental conditions, alongside ambient air temperature; Figure 9c shows real-time temperature profiles of skin simulators covered with different textile materials during a continuous 24 h outdoor cooling test in Zhenjiang, China; Figure 9d shows the time-dependent water vapor transmission rates of various textiles, highlighting that the treated CS/SiO₂ composite maintains effective transmission of water vapor from human perspiration; Figure 9e shows the systematic characterisation of breathability performance for nylon, cotton, CS, and CS/SiO₂; Figure 9f is about the quantitative analysis of liquid water transport differences among these four materials via water evaporation rate measurements. Collectively, these datasets establish a multidimensional evaluation framework for assessing radiative cooling efficiency and wearability comfort of the materials [51].

The resulting fabric exhibited a high solar reflectance of 82.3% and an infrared emissivity of 95.6%, significantly reducing surface temperature [51]. Compared to conventional cotton fabrics, this composite material lowered skin temperature by approximately 5.4 °C. The temperature reduction effect was even more pronounced (11.2 °C) compared to nylon textiles [51].

4.3. Antioxidant Functional Finishing

The antioxidant properties of functional textiles, particularly medical and hygiene-related fabrics, is essential for preventing oxidative degradation and maintaining their structural stability under oxidative conditions [123,124,125]. Studies have shown that chitosan–sericin composite finishing can effectively enhance the antioxidant capacity of cotton fabrics [107].

In this study, the finishing solution containing chitosan, sericin, citric acid, and NaH₂PO₂ catalyst was applied to cotton fabrics via a pad–dry–cure method under a controlled solution pH. The antioxidant performance of the finished fabrics was evaluated based on their radical scavenging activity (RSA). Experimental data demonstrated that all treated samples exhibited antioxidant activity, with RSA values increasing as the concentration of finishing agents increased [107] (see

Table 1. Effect of finishing agent concentration on radical scavenging activity of treated fabrics. (Reprinted with permission from Ref. [107]. Copyright 2024 Elsevier).

Concentration	RSA% of Sericin-Treated Fabric	RSA% of Chitosan-Treated Fabric	RSA% of Chitosan–Sericin-Treated Fabric
2 mg/mL	29.36 ± 0.63	25.04 ± 0.85	27.10 ± 0.60
4 mg/mL	35.02 ± 0.83	29.24 ± 0.59	32.43 ± 0.58
6 mg/mL	42.33 ± 0.51	33.42 ± 0.51	38.44 ± 0.60
8 mg/mL	48.12 ± 0.44	38.14 ± 0.31	42.13 ± 0.78
10 mg/mL	53.04 ± 0.23	42.35 ± 0.40	47.44 ± 0.5

).

The %RSA activity was measured by evaluating the reduction in the DPPH (2,2-diphenyl-1-picrylhydrazyl) indicator, a stable free radical characterised by a deep violet colour. Upon encountering an antioxidant, DPPH accepts an electron or hydrogen atom and is reduced, resulting in a visible colour change from violet to yellow. The absorbance of the solution is measured at 517 nm using a UV-Vis spectrophotometer.

In this method,

Where

 A0 = absorbance of DPPH solution without sample (control)

 A_s = absorbance of DPPH solution with sample

Furthermore, the chitosan–sericin composite finishing not only improved the antioxidant activity of the fabric but also retained the inherent antibacterial properties of chitosan, thereby imparting multifunctionality to the textile [126,127]. Additional studies have confirmed that this finishing treatment does not compromise the biodegradability of the fabric, ensuring that the treated textiles remain environmentally friendly after degradation [107].

4.4. Water-Repellent and Multi-Functional Activity

As a natural polycationic biopolymer, chitosan has found broad use in textile finishing to enhance fabric performance. It has been applied to improve properties including wrinkle resistance [90,109], water and oil repellence [128], flame retardancy [90,129], durability [105,130], blood repellence [131], and antistatic behaviour [132], among others [133,134]. Among these properties, water repellence and antibacterial functionality are particularly important, as they contribute to fabric longevity and broaden its range of applications.

Studies have shown that chitosan combined with silica (SiO₂) derived from rice husk ash can effectively impart hydrophobic properties to textiles [81]. The use of SiO₂ from rice husk waste provides a low-cost and sustainable method for textile finishing. The application process involves forming a chitosan–SiO₂ nanocomposite coating on the fabric surface, which enhances water repellence. Contact angle measurements confirmed that as the concentration of SiO₂ and chitosan increased, the contact angle of the treated fabric also increased, reaching a maximum of 161° at a chitosan–SiO₂ ratio of 0.8%:1%. This indicates the formation of a superhydrophobic surface. Additionally, the degree of hydrophobicity was influenced by the number of immersion cycles, with contact angles reaching 135° under certain treatment conditions [81] (Figure 10).

In addition to SiO₂-based coatings, chitosan alone has been used to enhance the water resistance of textiles. One study demonstrated that chitosan treatment could be applied using a simple impregnation process [109]. In this method, chitosan was dissolved in a 1% (w/v) acetic acid solution, and fabrics were treated via an impregnation–padding–drying process. During drying, chitosan formed a stable protective layer on the fibre surface, increasing water resistance while also improving mechanical strength and durability. Once cured, the chitosan creates an insoluble protective layer on the fibre’s surface. This layer fortifies the fabric, making it more resistant to deformation. Moreover, chitosan molecules fill the tiny fibre pores, establishing hydrogen bonds between the chitosan and the fibres. These bonds strengthen the amorphous areas, decreasing their movement and preventing wrinkles [109].

These results highlight the dual functionality of chitosan-based treatments. The chitosan-SiO₂ composite system not only retains chitosan’s inherent antibacterial properties but also significantly enhances the fabric’s hydrophobicity. Since chitosan originates from crustacean exoskeletons, it possesses some intrinsic water-resistant properties, which, when combined with SiO₂ from rice husk ash, further improve fabric hydrophobicity. This integrated finishing approach enables textiles to achieve both water repellence and antibacterial performance, expanding their potential applications in various functional and protective textile sectors.

5. Application of Chitosan in Textile Waste Management

5.1. Challenges in Textile Wastewater Treatment and the Functional Roles of Chitosan

Textile production is a significant contributor to industrial wastewater generation [56,57], containing a high concentration of dyes that exhibit strong visibility, resistance to degradation, and toxicity [58,135]. These contaminants severely endanger both ecological systems and human health. Anionic dyes, especially, exhibit poor degradability and potential for bioaccumulation, thereby intensifying environmental contamination [136,137]. Additionally, studies have shown that synthetic wastewater dyes are highly stable and resistant to natural degradation, leading to their prolonged persistence in the environment [136,138].

Currently, wastewater treatment technologies primarily include physicochemical methods (e.g., adsorption, coagulation–flocculation, and membrane separation), which rely on various adsorption mechanisms such as ion exchange, complexation, chelation, electrostatic interactions, and hydrogen bonding, and biochemical methods (e.g., phytoremediation and microbial degradation) [136,137]. Owing to the multiple functional groups and strong adsorption capacity, chitosan can effectively interact with pollutants through these mechanisms and has been widely applied in wastewater treatment [58].

As a natural macromolecular organic compound, chitosan contains hydroxyl (-OH) and amino (-NH₂) groups, which act as chelating sites capable of binding with dissolved heavy metals in wastewater [139]. Additionally, its cationic nature, adequate ability to capture pollutants, large molecular framework, wide availability, and economic feasibility make it highly attractive for wastewater treatment applications [140]. According to previous research chitosan and its derivatives, obtained through various modification methods, can effectively remove different types of dyes [60] and have been widely utilised in synthetic and natural dyeing processes in textiles [48,54,141].

5.2. Application of Chitosan in Dye Removal

Due to its highly efficient adsorption properties, chitosan and its composite materials have been widely investigated for dye removal in wastewater treatment [54,58,142,143]. Research has demonstrated that chitosan powder and chitosan microspheres can effectively remove synthetic dyes such as Direct Blue 78 (DB78), with different modification techniques further enhancing adsorption performance [58].

In experimental studies, SEM analysis revealed that before adsorption, chitosan powder revealed an uneven surface featuring a prominently developed pore structure (Figure 11a). After adsorption, the pore structure was significantly reduced due to the saturation of dye molecules (Figure 11b). Additionally, the application of polyacrylamide gel facilitated the sedimentation of chitosan particles, improving treatment efficiency (Figure 10c) [136]. Chitosan and its blends or composites have demonstrated strong adsorption capacities across different dye removal studies and have been widely explored for wastewater treatment applications [58].

Furthermore, studies indicate that the modification of chitosan can significantly enhance its adsorption capacity. Chemically or physically modified chitosan materials can achieve adsorption capacities exceeding 200 mg/g, and after multiple reuse cycles, they can still retain over 80% of their adsorption efficiency [137]. Moreover, surface modifications can enhance the selectivity of chitosan toward specific dyes, further improving wastewater treatment performance [137] (Figure 11).

5.3. Adsorption Performance and Treatment Efficiency of Chitosan-Based Composites

Experimental data (Figure 12) showed that treating synthetic wastewater with 4.5 g/L of chitosan powder or chitosan microspheres led to respective dye removal rates of 94.1% and 80%. [136]. Among these, the combination of chitosan powder and polyacrylamide gel not only enhanced the removal efficiency but also reduced the sedimentation time from 8 h to just 5 min (Figure 11a). In contrast, chitosan microspheres achieved instantaneous sedimentation without requiring additional coagulants but exhibited a slightly lower removal efficiency (Figure 11b) [136]. These results indicate that the morphology of chitosan particles and the use of additives significantly influence adsorption efficiency and sedimentation dynamics (Figure 12).

Additionally, chemical modifications of chitosan can enhance its thermal stability and reusability, thereby improving its cost-effectiveness and environmental applicability in textile wastewater treatment [137]. Recent advancements in chitosan-based materials have focused on improving adsorption efficiency, durability, and adaptability to different wastewater conditions, contributing to the development of more sustainable water treatment technologies.

6. Discussion

This review analyses the applications of chitosan in future applications and current research in the textile sector from a life cycle perspective, integrating findings from 142 academic studies. It provides a comprehensive understanding of the role of chitosan in fibre production, dyeing, finishing, and wastewater treatment. The study highlights the key functional properties of chitosan, including its renewability, biodegradability, antimicrobial activity, and adsorption capacity, and explores its potential in pollution control and resource optimisation within textile manufacturing. Additionally, the review summarises existing research on the use of chitosan in textile production and waste management, as well as its demonstrated effectiveness in eco-friendly dyeing, functional finishing, and wastewater treatment. While chitosan has exhibited promising sustainability characteristics across multiple applications, systematic assessments of its large-scale industrial viability remain relatively limited. Based on the findings presented in earlier sections, this discussion further evaluates chitosan’s contributions to sustainability in the textile industry, assessing its potential in decarbonisation, resource circularity, and market applications, while also identifying challenges and directions for future research.

Chitosan offers significant advantages in reducing carbon emissions and improving resource efficiency in the textile industry. Unlike synthetic polymers derived from fossil fuels, chitosan originates from chitin, a byproduct of the seafood industry. Its utilisation not only mitigates biological waste accumulation but also provides a low-carbon, renewable raw material for textile production [46,62,82,91,144,145]. Studies have demonstrated that chitosan fibres, produced via wet spinning and electrospinning, can partially replace petroleum-based synthetic fibres while maintaining, or in some cases enhancing, mechanical and functional properties [47,51,94,95,96]. Particularly, antimicrobial activity, UV protection, and moisture regulation make chitosan fibres highly desirable for functional textiles such as sportswear and medical fabrics [52,85,89,90]. Moreover, in textile dyeing, chitosan enhances dye fixation efficiency, reducing the need for salts and auxiliaries, thereby lowering dye hydrolysis and wastewater discharge [110,111]. These characteristics contribute to a more resource-efficient dyeing process, aligning with the broader goal of reducing carbon footprints in textile production [47,48]. As industries strive to transition towards low-energy, low-pollution manufacturing models, integrating chitosan-based materials into textile processing presents a viable approach to achieving sustainability objectives.

Chitosan’s biodegradability makes it a promising material for addressing textile waste pollution within a circular economy framework. Unlike conventional synthetic fibres, which often end up in landfills or contribute to microplastic pollution, chitosan-based textiles are suitable for composting or material recovery after use, supporting closed-loop recycling systems [36,92,107]. Additionally, chitosan’s applications in wastewater treatment further enhance its sustainability value. Its high adsorption capacity enables the extraction of colorants, metallic ions, and organic contaminants from textile effluents, thereby improving water quality and facilitating resource recovery [58,59,60]. Compared to energy-intensive coagulation or membrane filtration techniques, chitosan-based treatment methods can minimise the use of additional chemical reagents, reducing the environmental impact while maintaining efficient industrial operations [136,137].

Beyond their sustainability benefits, chitosan’s functional properties present notable market potential. With antimicrobial activity, UV protection, and moisture regulation, chitosan fibres show promise for use in functional textiles, including sportswear and medical fabrics [50,102,107,122]. Research has demonstrated that chitosan-based finishing technologies can provide long-lasting antibacterial effects, enhance fabric durability, and reduce the frequency of product replacement due to material degradation or contamination [104,105,107,112]. These attributes play a dual role in the extended lifespan of textiles and support more sustainable consumption practices by reducing waste and resource consumption [8,43,47]. However, fully leveraging this market potential will require addressing challenges related to cost, processing efficiency, and consumer acceptance.

Although chitosan exhibits many beneficial properties, its large-scale use in textile applications is still hindered by various technical and industrial limitations. Scalability remains a key issue, as the production capacity of chitosan-based fibres is currently lower than that of conventional synthetic fibres. The cost-effectiveness of electrospinning and composite fibre production requires further optimisation to enhance economic viability [43,51,94]. Another challenge concerns the long-term stability of chitosan in textiles. For instance, further investigation is needed to determine whether chitosan-based finishing agents maintain their effectiveness after repeated washing and wear, as well as to evaluate their compatibility with existing textile processing techniques [107]. Additionally, although chitosan production is generally considered environmentally favourable compared to synthetic materials, its overall energy consumption and byproduct management throughout its lifecycle require a more comprehensive assessment to validate its long-term sustainability [69,82].

Addressing these challenges is essential to fully realising the application value of chitosan in the textile field. Future research should focus on improving chitosan processing techniques, enhancing its durability, and expanding its applications in textile manufacturing. Specifically, advancements in high-performance coatings, smart textiles, and biodegradable fibre development could significantly broaden the scope of chitosan’s industrial applications [76,104,109]. Additionally, further refinement of lifecycle assessment (LCA) methodologies will be essential for quantifying chitosan’s environmental benefits across the entire textile supply chain [24,46,82,91].

7. Conclusions

In summary, this review emphasises the transformative potential of chitosan in promoting sustainability in the textile industry. Its role in decarbonisation, resource circularity, and waste management offers a viable pathway for transitioning towards greener, more efficient production models [43,58,59]. Moreover, chitosan’s functional advantages and market appeal position it as a promising alternative to conventional textile materials [53,61,90,107,133]. However, achieving this potential necessitates continued technological refinement, market development, and policy support to facilitate its integration into mainstream textile production.

Despite growing interest, many chitosan-based applications remain at the laboratory scale. Key areas, including wastewater treatment and functional finishing, are still undergoing development and require further technical validation before industrial application is feasible. In addition, the current lack of comprehensive lifecycle assessments and economic evaluations limits the ability to fully quantify long-term impacts. Future research should therefore prioritise scaling production processes and systematically assessing feasibility to support the broader integration of chitosan in sustainable fashion production.