Dye Bath Research Articles

Color fastness and antimicrobial activity of Gardenia jasminoides extract against antimicrobial-resistant Staphylococcus aureus

This study investigated the antimicrobial efficacies of fabrics (100% cotton and 100% silk) dyed with an ethanol extract of Gardenia jasminoides (G. jasminoides). More specifically, these fabrics were dyed using a G. jasminoides extract with a dye bath ratio of 1:20 at 40–60 °C for 60 min, followed by post-mordanting. The concentrations of the aluminum sulfate, copper sulfate, and ferrous sulfate mordants were each set to 3% (o.w.f.). The samples were mordanted using a mordant bath ratio of 1:30 at 40 °C for 20 min. The iron mordant slightly increased the dye uptake (K/S) of the cotton fabric but did not increase the dye uptake (K/S) of the silk fabric. The antimicrobial efficacies of the dyed fabrics against methicillin-resistant Staphylococcus aureus (MRSA) ATCC 33591 were determined to be 99.8 and 87.8% for the cotton and silk fabrics, respectively. The inhibitory effects of the cotton and silk fabrics against MRSA were 30.5 × and 167.3 × the inoculum size, respectively, indicating the superior inhibitory effect of the dyed cotton fabric. These results suggest that the fabrics dyed with G. jasminoides extract may possess antibacterial activity against antimicrobial-resistant bacteria.

Eco-friendly utilization of microwaves for extraction of dye from logwood and Its application onto silk

For minimizing the pollution associated with synthetic colorants, the world again is going to realize the benefits of natural colorants in applied fields such as textiles, food flavors, etc. As part of the ongoing research project, hematein is being investigated as a potential natural colorant derived from logwood chips, and its implementation on silk fabric is being investigated under the effect of microwave radiations. A number of dyeing variables, including pH, dyeing duration, temperature of the dye bath, volume of extraction, and salt concentration, have been investigated, and the effect of isolation medium has also been evaluated. For new shades with improved fastness ratings, extracts of various sustainable bio-mordants and chemical mordant such as salts of aluminum and copper, and tannic acid were also used. An experiment revealed that treating un-irradiated silk with 40 mL of methanolic extract with a pH of 2, irradiated for 6 min, produced outstanding outcomes when dyed at 90°C for 60 min. The dyeing process included the addition of 9 g of salt per 100 mL of solution as an exhausting agent. In these circumstances, the utilization of sustainable mordants has not only enhanced the ratings of color fastness but has also rendered the procedure more environmentally friendly and less polluting. Therefore, microwave radiation has great potential for extracting colorants from plants and effectively applying them to natural materials under decreased conditions.

Dyeing ability of C. longa L. and T. stans (L.) Juss. Ex Kunth on unmordanted and mordanted silk and cotton fabrics

The work was on the extraction of both the C. longa rhizomes and the petals of T. stans using four different solvents (ethanol, ethyl acetate, water, and n-hexane). The dyeing potential of the C. longa and T. stans extracts was evaluated on cotton and silk fabrics without or with mordants using potash alum, phosphomolybdic acid, iron (II) sulphate, and tartaric acid at varied temperatures and tested for colour fastness properties (wash and light fastness). The pH and absorbance of the dye bath before and after dyeing were studied. However, cotton, which is cellulosic, was better dyed than silk, which is proteinous, which showed a better choice for fabrics dyeing at 80 °C; hence, it had a good colour efficiency. Iron (II) sulphate exhibited complexes in the octahedral configuration of the coordination six with CH2O- of cotton and NH3+ and COO- of silk fabric. In addition, it was also observed that the higher the dyeing temperature, the greater the dyeing intensity. The spectroscopic characterization of the extracts was determined with the help of UV-Vis and FTIR. The UV-Vis and FTIR spectral analyses revealed the chromophore, auxochrome groups, and functional groups, respectively, within the extracts. Curcumin and rutin were identified as being responsible for the dyeing of the fabric.

Eco-Friendly Dyeing Processes of Nylon 6.6 Woven Fabrics with Used Coffee Grounds (UCG)

The increasing demand for sustainable practices in the textile industry has led to the exploration of natural dyes and eco-friendly dyeing processes. This study focuses on the potential of used coffee grounds (UCG) as an eco-friendly natural dye for Nylon 6.6 woven fabrics. Five dyeing processes were evaluated, varying in the use of mordants and acids, to assess their impact on the color saturation, colorfastness to laundering, and crocking resistance of Nylon 6.6. fabric. The processes included a control with no mordant or acid and others that incorporated tannic acid, acetic acid, and ferrous sulfate heptahydrate. The results demonstrated that process 4, which combined tannic acid pre-mordanting with acetic acid in the dye bath, provided the best balance between color saturation and colorfastness. Process 2, utilizing only tannic acid, offered some durability in laundering and crocking tests. Process 5, being the least eco-friendly process, demonstrated high color saturation, but it performed poorly in colorfastness to crocking, which means that it released the UCG-based dye after rubbing the dyed Nylon 6.6. fabric. The findings confirm that UCG can be an effective and sustainable natural dye for Nylon 6.6, with pre-mordanting and acid treatment significantly enhancing dye uptake and retention. However, further research is needed to optimize color intensity and expand the application of UCG in textile dyeing.

Bio Dyeing of Nylon 6 Fabrics Using Beetroot and Natural Mordants

AbstractIn this paper, the potential of beetroot as a natural source to dye a synthetic fiber that is, nylon 6 fabric, has been examined. We analyzed the impact of the most important dyeing parameters, such as dyeing temperature, dyeing time, pH of the dye bath, and dye concentration, on the dyeing efficiency of the nylon 6 fabric. We achieved the optimal conditions for nylon dyeing by beetroot at the boiling temperature for 60 min using 100% on the fabric weight (owf) dye under acidic conditions. Also, to attain suitable color fastness, we used four different natural mordants (pomegranate peel, walnut husk, pistachio hull, and Terminalia Chebula) before the dyeing process. We also examined the effect of four commonly used metal mordants on the dyeing efficiency. FTIR, SEM, EDX and TGA were then conducted to justify the presence of mordants and dyes on the substrate. We discovered that pre‐mordanting generated colorful fabrics based on the type of mordants used. Also, various natural mordants could produce different color strengths, such that the walnut husk had the highest color strength among the used mordants. The obtained color fastness against washing of all bio‐mordants was rated as excellent and the light fastness of Terminalia Chebula was surprisingly excellent. Bio‐mordants also exhibited equivalent washing fastness to metal mordants, even surpassing them in terms of light fastness. The EDX spectra also showed peaks corresponding to carbon (C), nitrogen (N), and oxygen (O). Finally, the fabric mordanted with pomegranate peel exhibited very less mass loss, thus indicating thermal stability.

Cotton Fabric Coating by Cationic Starches to Aim for Salt‐Free Reactive Dyeing

AbstractCationic starch (CatS) coating of cellulose fabrics enables salt‐free reactive dyeing. However, the relation of the degree of substitution and CatS concentration in the dyeing procedure are open issues. Accordingly, three cationic starches of increasing degree of substitution were used at different concentrations for the coating of cotton fabrics. Fabrics were evaluated for stiffness, dye uptake, dye exhaustion, wash fastness and nitrogen content.With an increasing degree of substitution coating solutions become more viscous, resulting in increased wet pick‐up and less stiff coated fabrics. These fabrics show increasing dye absorption and color generation. Due to the molecular size of the cationic starch, yarn/fiber ring dyeing is supposed present. Specifically, color generation can be adjusted by initial cationic starch coating concentration. Above 5 % CatS concentration ceases to have an increasing coloration effect. Pre‐treating a cellulose fabric with approximately 2.2 % CatS (Ds=0.7) enables similar coloration to a standard reactive dyeing protocol. Light fastness is reduced by 1–1.5 compared to salt‐based reactive dyeing. Rub fastness decreases by 1–2 only for higher substituted cationic starches (Ds=0.7). Nitrogen analysis reveals that a share of the CatS elutes off the fabrics into the dye bath.

Cinnamon and Eucalyptus Extracts: A Promising Natural Approach for Durable Mosquito-Repellent Fabrics with Multifunctionality.

Mosquitoes are highly important carriers of diseases, such as malaria, dengue, chikungunya, and various other life-threatening illnesses. Traditionally, many chemicals, such as plant extracts, oils, and smoke, have been employed for the purpose of repelling mosquitoes. Various plants possess essential oils and chemicals that have been proven to be good insect repellents and are commonly regarded as weeds. The present study focused on the development of eco-friendly, nonhazardous mosquito-repellent fabrics using cinnamon and eucalyptus extracts. First, eucalyptus and cinnamon extracts were produced separately using ethanol and water as solvents with and without heating. Forty-eight different fabric samples were prepared by applying these extracts at three levels of process application temperature. A steam dye bath sampling machine was utilized to execute the extraction application process on fabric samples. The mosquito repellency performances of all of the samples were evaluated using the cage test method. The cage test revealed that all of the samples of eucalyptus and cinnamon extract-applied fabrics showed mosquito repellency performance at some level. However, the fabric samples treated with the heated extract of eucalyptus ethanol (EE-H) at 60 °C showed the best results in terms of mosquito repellency (85.56%) among all combinations. In addition to repellency, the impact of washing durability, UV shielding, and antibacterial performance was also evaluated. This research demonstrated a new method for creating a fabric that repels mosquitoes and has effective antibacterial properties as well as promising ultraviolet protection factor (UPF) rating. This fabric protects the wearer from the significant health risks posed by mosquitoes and harmful UV radiation while also maintaining its cleanliness. Moreover, the utilization and implementation of plant-derived coatings on textiles contribute to the advancement of sustainable methods (SDG 9 and SDG 12) in the chemical processing industry of textiles, ultimately leading to a reduction in their environmental footprint.

The Environmental Impact of Low-Pressure Anhydrous Dyeing Technology for Polyester: Carbon Footprint Quantification and Evaluation

Many emerging dyeing technologies have recently entered laboratory research or industrial production phases. However, only a few studies have evaluated and compared the environmental impact of different dyeing systems. This study calculated the carbon footprint of low-pressure anhydrous dyeing for polyester and compared with conventional water bath dyeing. The results showed that the carbon footprint of the anhydrous dyeing process was 1670 kgCO2 eq/1000 kg polyester. Steam occupied the most significant proportion, accounting for 55.5%, followed by electricity at 35.5%. The waste has the lowest environmental impact, with 0.55%. Uncertainty analyses showed that the data and results in this article were reliable. The results of the sensitivity analyses indicated that more attention should be paid to the data quality of steam and electricity. Compared with the traditional water bath dyeing process, the low-pressure anhydrous dyeing system can reduce greenhouse gas emissions by more than 30% and, more importantly, can avoid almost all the consumption of clean water. This anhydrous dyeing system can save water and reduce carbon emissions, which is of positive significance to the sustainable development of the textile and fashion industry. Further studies could use the water footprint as an indicator to evaluate this dyeing system in terms of water consumption and potential environmental impact.

Down flow jet-loop reactor with NF-RO membrane system for the treatment of textile wastewater

Textile industries are significant consumers of fresh water, extensively using it for washing and dyeing processes. The effluent from these operations contains various chemicals, including complex synthetic dyes, NaCl and Na2SO4 necessitating efficient treatment before discharge into water bodies. Zero Liquid Discharge (ZLD) technology facilitates complete water recovery but leads to substantial solid waste accumulation, which poses challenges for reutilization. This study introduces an innovative approach using a Downflow Jet Loop Reactor combined with ozone and activated carbon to effectively remove color and Chemical Oxygen Demand (COD) from textile effluent. Furthermore, a combination of Nanofiltration (NF) and Reverse Osmosis (RO) membrane systems ensures comprehensive purification by effectively separating inorganic salts. Experimental results demonstrated a maximum color removal of 81.25 % from the textile effluent. The fabricated PSF/PVDF NF membrane exhibited exceptional capacity for rejecting divalent salts. Additionally, the RO reject, which is a concentrated solution of salts and contaminants, was successfully reused in a dye bath for cotton fabric dyeing. This approach highlights the practicality, sustainability, and resource conservation potential within the textile production cycle. It underscores the importance of a comprehensive water treatment strategy for achieving sustainable textile production.

Surface modification of fibres using bipolar pulsed driven DBD plasma based KrCl* and XeI* exciplex sources

This work demonstrates the application of DBD plasma-based exciplex UV technology for surface modification of natural fibres. KrCl* (222 nm) and XeI* (253 nm) exciplex lamps have been developed and characterized in terms of the applied voltage, applied frequency, gas pressure, and absolute UV light intensity. The measured radiated intensities are 2.45 mW/cm2 and 1.91 mW/cm2 for 222 nm and 253 nm exciplex lamps, respectively. The change in physicochemical properties such as tensile strength, weight loss, wettability, surface morphology, and chemical composition, are evaluated using different characterization techniques ̶ like Contact Angle Goniometry, Thermogravimetric Analysis (TGA), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Field Emission Scanning Electron Microscopy (FE-SEM), and Energy Dispersive X-ray (EDX) analysis, etc. The results are compared with untreated fibres to see the effect of different doses of UV222 and UV253 on the different properties of fibres. It is inferred that the exciplex UV222 treated fibres have a higher concentration of different polar groups (− OH, − COOH, etc.). Much improvement in the dyebath ability of the natural fibre is achieved using a 222 nm exciplex light source, which reduces the dye concentration in the textile effluents and improves the dye adhesion to the fibre. It has been found that the fibre's hydrophilicity and dye bath capabilities have improved significantly.

Adsorption kinetics and thermodynamics of metal complex acid dyes on silk fabric

This study reports the adsorption phenomena of metal complex acid dyes onto silk fabric. Two commercial metal complex acid dyes namely Bestalan Yellow SF and Bestalan Navy SF were adsorbed onto degummed silk fabric. The functional properties and surface morphology of silk fabric were investigated with FT-IR spectroscopy and FE-SEM respectively. The typical absorption band of C = O stretching was found at 1620 cm−1 indicating amide I structure and C-N stretching as well as N-H bending vibrations were observed at 1510 cm−1 suggesting the β-sheet crystallites of amide I and amide II silk proteins. The effectiveness of degumming performance was confirmed by SEM images. The adsorption of dyes by silk fabric was investigated with respect to pH, initial dye bath concentration, and contact time. It was found that the adsorption of dye onto silk fabric was highly influenced by the dye bath pH, initial dye concentration, and contact time. The higher dye adsorption was observed at acidic dye bath condition (pH = 3.5). The adsorption of dye was also increased with the increase of the initial dye bath concentration. The dyes adsorption reached at equilibrium condition after 80 min. The adsorption isotherm and kinetics were also evaluated based on the experimental results. The adsorption pattern fitted well to the Langmuir adsorption isotherm with high correlation coefficient (R 2>0.97) for both dyes. The kinetic parameters suggested that the pseudo-second-order model is more suitable compare to the pseudo-first-order model considering the higher regression coefficients ( R 2 = ∼ 0.99 ) . The maximum adsorption of Bestalan Yellow SF and Bestalan Navy SF was found to be 232.5 and 222.2 mg/g respectively. The thermodynamic data were studied at 25, 40 and 60 °C. The change of Gibbs free energy of the system was positive indicating the spontaneous nature of the adsorption. The values of ΔH (-4.68 kJ/mole −3.65 kJ/mole) suggested the exothermic environment and the negative values of ΔS (-0.035 and −0.034 kJ/mole/k) advocated the good interaction between the metal complex acid dyes and silk fabric. The Langmuir adsorption model and pseudo-second-order kinetic suggested that the dyeing of metal complex acid dyes on silk fabric was controlled by ion-exchange chemical reaction.

Enhanced filtration membranes with graphene oxide and tannic acid for textile industry wastewater dye removal

ABSTRACT A novel modification technique employing a layer-by-layer (LbL) self-assembly method, integrated with a pressure-assisted filtration system, was developed for enhancing a commercial polyethersulfone (PES) microfiltration (MF) membrane. This modification involved the incorporation of tannic acid (TA) in conjunction with graphene oxide (GO) nanosheets. The effectiveness of the LbL method was confirmed through comprehensive characterization analyses, including ATR-FTIR, SEM, water contact angle (WCA), and mean pore size measurements, comparing the modified membrane with the original commercial one. Sixteen variations of PES MF membranes were superficially modified using a three-factorial design, with the deposited amount of TA and GO as key factors. The influence of these factors on the morphology and performance of the membranes was systematically investigated, focusing on parameters such as pure water permeability (PWP), blue corazol (BC) dye removal efficiency, and flux recovery rate (FRR). The membranes produced with the maximum amount of GO (0.1 mg, 0.55 wt%) and TA as the inner and outer layers demonstrated remarkable FRR and significant BC removal, exceeding 80%. Notably, there was no significant difference observed when using either 0.2 (1.11 wt%) or 0.4 mg (2.22 wt%) in the first layer, as indicated by the Tukey mean test. Furthermore, the modified membrane designated as MF/TA0.4GO0.1TA0.4 was evaluated in the filtration of a simulated dye bath wastewater, exhibiting a BC removal efficiency of 49.20% and a salt removal efficiency of 27.74%. In conclusion, the novel PES MF membrane modification proposed in this study effectively enhances the key properties of pressure-driven separation processes.

Ephemeral Orchil in the Lady and the Unicorn Tapestry: Recipe, Experimentation, and Characterisation

Spectroscopic techniques were carried out to identify the dyes used on the famous mediaeval Lady and the Unicorn tapestries kept in the Cluny Museum. Among the six tapestries, La Vue shows a colour variation between the front, which appears blue, and the back, which appears violet, on the Lady’s skirt. In the Middle Ages, it was common for the violet colour to be made with a blue dye bath (woad or indigo) followed by a red bath, which could be madder, cochineal, kermes, or orchil. Since orchil is known to be very unstable to light, its potential use in the original recipe was investigated and a study on this dye was performed. Contactless analyses (hyperspectral imaging in the visible-near-infrared range and UV fluorescence spectroscopy) were carried out on both the tapestry and mock-ups prepared following various mediaeval recipes. The investigation allowed for the identification of woad and orchil on the back of the tapestry, which was preserved from exposure to light. In addition, an ageing study elucidated colour degradation, revealing not only the different responses to light of different dyes but also the effect of specific dye preparations on light resistance. The experiments showed that the longer the maceration, the higher the light resistance of the dye. Furthermore, the red orchil colour fades faster than the woad.

Study of reactive dyes and their hydrolyzed forms in a real trichromatic dyeing process by capillary electrophoresis with UV detection.

Detecting the concentration of reactive dyes and their hydrolyzed products is essential for controlling the dyeing process and is an important guide for upgrading and improving textile dyeing technology. In this study, capillary electrophoresis (CE) with UV detection was for the first time applied in a real trichromatic dyeing process to provide qualitative and quantitative determination of reactive dyes and their hydrolyzed forms. Here, three original reactive dyes (SES-Cl-red-195, SES-Cl-yellow-145, and SES-Cl-blue-194), their vinyl sulfone forms (VS-Cl-red-195, VS-Cl-yellow-145, and VS-Cl-blue-194), and complete hydrolyzed forms (HES-OH-red-195, HES-OH-yellow-145, and HES-OH-blue-194) could be baseline separated in our developed BGE comprised of 10.0 mol/L Na2B4O7, 15% (V/V) ACN at pH 8.50 that adjusted by 0.50 mol/L H3BO3. The LODs (S/N = 3) of nine analytes ranged from 0.3 to 1.3 mg/L, and high sensitivities were achieved with UV detection. The RSDs of peak area and migration time were in the ranges of 1.4-3.8% and 0.39-1.29%, which indicated the CE methods were reliable for studying different dye forms in complex dye baths, and for evaluating dyeing process quality. Thus, the percentage of dye-uptake in single and trichromatic combination dyes was calculated based on the concentration of the original and their vinyl sulfone and hydrolyzed forms, and the result was consistent with the traditional UV-Vis method.

Environmentally Friendly Approach for Treatment Textile Wastewater by Nanobubble Water Technology and Enzymes

One of the most important issues about textile industry is its negative environmental impacts because of the pollution produced. Herein, decolorization processes of different-colored reactive dyeing baths using eco-friendly ways; nanobubbles and enzymes, was discussed. Decolorizations were evaluated by examining the transmittance and chemical oxygen demands of the treated wastewater baths were measured. The results showed that nanobubbles could be used in decolorization while laccase and peroxidase enzymes increased the decolorization effect of nanobubbles. In addition to the decolorizing effect of nanobubbles, it was an important environmental advantage that the corresponding process provided lower chemical oxygen demand than that in the untreated wastewater. The results of the study reveal that it is possible to use nanobubble in decolorization and this technology is an important wastewater treatment technology in protecting the environment by reducing the chemical oxygen demand of wastewater.

Novel Disperse Dyes Based on Enaminones: Synthesis, Dyeing Performance on Polyester Fabrics, and Potential Biological Activities.

1-(3-aryl)-3-(dimethylamino)prop-2-en-1-one (enaminones) derivatives and the diazonium salt of para-chloroaniline were used to synthesize several novel disperse azo dyes with high yield and the use of an environmentally friendly approach. At 100 and 130 °C, we dyed polyester fabrics using the new synthesized disperse dyes. At various temperatures, the dyed fabrics' color intensity was assessed. The results we obtained showed that dyeing utilizing a high temperature method at 130 °C was enhanced than dyeing utilizing a low temperature method at 100 °C. Reusing dye baths once or twice was a way to achieve two goals at the same time. The first was obtaining a dyed product at no cost, and the second was a way to treat the wastewater of dyeing bath effluents and reuse it again. Good results were obtained for the fastness characteristics of polyester dyed with disperse dyes. When the disperse dyes were tested against certain types of microbes and cancer cells, they demonstrated good and encouraging findings for the potential to be used as antioxidants and antimicrobial agents.

Assessing the dyeing efficacy and environmental impact of cotton fabric dyed with sawmill bio‐waste extracts and metal salts

AbstractTextile coloration is a complex process involving the interaction of dye molecules with fibers in a dye bath. Synthetic dyes pose environmental hazards, leading to increased interest in natural dyes sourced from plants, animals, and minerals. However, natural dyes often require mordants for application to textiles. Despite their eco‐friendliness, natural dyes can exhibit poor wash fastness on fabrics, necessitating further research to enhance their performance. This study investigates the use of mahogany sawdust extract as a natural dye for cotton coloration, focusing on the enhancement of fastness properties through metallic mordants and associated environmental risks. Mahogany sawdust, rich in flavonoids and tannins, shows promise as a sustainable alternative to synthetic dyes. The dyeing process involves the extraction of natural dyes from sawmill bio‐waste and subsequent application onto cotton fabrics using various metallic mordants. Evaluation of colorfastness properties, color strength, color coordinates, tensile strength, FTIR, and SEM analysis provides insights into the dye‐fiber interactions and fabric properties. Environmental risk assessment considers metal exhaustion onto fabric surfaces, residual metal concentrations in mordant baths, and metal content in dyeing wastewater. Overall, this study contributes to the development of sustainable dyeing processes and highlights the importance of environmental considerations in textile coloration.Highlights Mahogany sawdust extract: potential natural dye for sustainable cotton coloration. Metallic mordants enhance colorfastness and fabric durability in dyeing processes. Comprehensive analysis reveals the intricate dynamics of dye‐fiber interactions. Environmental risk evaluation guides sustainable textile manufacturing practices. Research paves the way for greener, more sustainable textile industry practices globally.

Facile physical entrapment of halochromic dye via UV-photografting for the fabrication of colorimetric cotton sensors to detect toxic ammonia gas

Textile-based halochromic gas sensors are useful for detecting volatile organic compounds (VOCs) such as ammonia, because they undergo changes that are distinguishable to the naked eye. Herein, we report the UV photografting system we developed for the fabrication of halochromic cotton sensors with reduced amounts of salt, resources, and effluents. First, 4-hydroxycoumarin-based dye (HD) was synthesized as a halochromic indicator, where after the synthesized dye, monomer, and photoinitiators were introduced to a dye bath to fabricate the UV photografting system. This system was produced by grafting monomers on a fiber surface under UV light irradiation to formulate a polymer network that entraps dye molecules. A series of different monomer concentrations and photoinitiators were introduced to the dye bath. Subsequently, the dyeability and gas detection performance of the fabricated cotton sensors were evaluated. In addition, fastness and reusability tests were performed to ensure the fabricated cotton sensors were durable and sustainable. The dyeability of the fabricated cotton sensors increased as the monomer concentration increased and the color change upon exposure to ammonia gas followed the same tendency. The fabricated cotton sensor prepared with the highest monomer concentration underwent a distinctive color change upon exposure to ammonia gas for 300 s (ΔE > 15). Furthermore, the cotton sensor exhibited remarkable durability to washing (wash fastness level: 5, ΔE maintenance rate after washing: ∼85 %) and rubbing (rubbing fastness level: 4/5, ΔE maintenance rate after rubbing: ∼95 %). Reusability testing of the fabricated cotton sensors showed that the halochromic property was retained after repeated washing (10 cycles). The results confirmed that the UV-induced photografting performance had been optimized and suggested that UV-induced photografting offered an eco-friendly alternative to conventional dyeing for the fabrication of halochromic textile sensors.

Comprehensive study of Fenton reaction efficiency on textile wastewater treatment from dye solution to real effluent with emphasis on Fukui function analysis

This study investigated the continuous degradation monitoring of three reactive dyes, reactive yellow 176 (RY), reactive Blue 4 (RB) and reactive red 293 (RR), both in separate solutions and in a mixture, along with their corresponding dye bath and industrial dyeing effluent, using Fenton reaction. A kinetic study was conducted to compare the degradation efficiency of the studied solutions. This work provides important yield of dye degradation, where the results showed that RB, RY, and RR had 96.64 %, 92.47 %, and 73.27 % color removal, respectively, within a two-hour reaction time. The pseudo-second-order model fit well to describe the degradation of RR and RY, while the zero-pseudo-order model provided a better fit for RB. The dye mixture exhibited 57 % color removal, whereas the dyeing bath and real effluent showed 41 % and 36 % removal, respectively, over a two-hour reaction time. Moreover, significant reductions in chemical oxygen demand (COD) and biological oxygen demand over 5 days (BOD5) were observed, with the real effluent demonstrating a 73.91 % COD reduction and an 86.66 % reduction in BOD5. The COD and BOD5 reductions for the dye bath were 67.53 % and 95 %, respectively. Additionally, COD and BOD5 reductions of 72.96 % and 96.66 %, respectively, were observed for the dye bath. DFT calculations were employed to elucidate the regioselectivity of radical oxidation of the three reactive dyes by Fenton's reagent, providing insights into global and local reactivity descriptors. Toxicity studies further underscored the efficacy of the Fenton reaction in wastewater treatment. Additionally, UV–visible spectral analysis before and after 12 h of Fenton reaction revealed total discolouration and a reduction in UV and visible peaks across all reactions, indicating comprehensive dye degradation and reduction.

Investigation of process parameters for eco-friendly indigo dyeing of cotton fabric with reducing sugars

Purpose The application of indigo dyes in the denim industries has been criticised due to the introduction of non-renewable oxidation products into the environment. Previous studies have investigated that reducing sugars can be used as green alternatives to sodium dithionite in the indigo dyeing of cotton fabric owing to their reduced and stable redox potential in the dye bath. The purpose of this study was to dye denim cotton fabric with indigo dye using various reducing sugars and alkalis. The use of sucrose and potassium hydroxide (KOH) for indigo dyeing has been explored for the first time. Design/methodology/approach A mixed factorial design with four variables including alkali, pH, number of dips and type of reducing sugar at different levels was studied to identify a significant correlation between the effect of these variables on the colour strength and fastness properties of the dyeings. Findings Investigations were made to examine the significant factors and interactions of the selected responses in the eco-friendly dyeing method. This process has the potential to reduce the load of sulphite and sulphate generated in the dyebath due to the use of a conventional reducing agent, sodium dithionite. The colour strength of the dyeing reduced with fructose was found to be better than other reducing sugars and significantly influenced by the number of dips, pH levels and the interaction between pH and reducing sugars. Using fructose for indigo dyeing with two dips at a pH of 11.5, using KOH as an alkali, results in higher colour strength values. The fastness properties of the indigo-dyed sample with reducing sugars ranging from fair to good or good to excellent. Specifically, colour change receives a rating of grey scale 3–4, staining 4–5, dry rubbing 4 and light fastness 3–4. These assessments hold true across various factors such as the type of reducing sugar, alkali, pH and the number of dips. The optimised parameters leading to improved colour strength and fastness properties are also discussed. Originality/value This dyeing technique is novel and a green alternative to dithionite denim dyeing. This process is found to be useful for indigo dyeing of denim fabric leading to reduced and stable redox potential in the dyebath and acceptable colour strength of the dyed fabric.