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While aiming to create methods for fibre recycling, the question of colours in waste textiles is also in focus; whether the colour should be kept or should be removed while recycling textile fibre. More knowledge is needed for colour management in a circular economy approach.

The research included the use of different dye types in a cotton dyeing process, the process for decolourizing and the results. Two reactive dyes, two direct dyes and one vat dye were used in the study. Four chemical treatment sequences were used to evaluate colour removal from the dyed cotton fabrics, namely, HCE-A, HCE-P-A, HCE-Z-P-A and HCE-Y-A.

The objective was to evaluate how different chemical refining sequences remove colour from direct, reactive and vat dyed cotton fabrics, and how they influence the specific cellulose properties. Dyeing methods and the used refining sequences influence the degree of colour removal. The highest achieved final brightness of refined cotton materials were between 71 and 91 per cent ISO brightness, depending on the dyeing method used.

Only cotton fibre and three different colour types were tested.

With cotton waste, it appears to be easier to remove the colour than to retain it, especially if the textile contains polyester residues, which are desired to be removed in the textile refining stage.

Colour management in the CE context is an important new track to study in the context of the increasing amount of textile waste used as a raw material.

This paper aims to select a type of mordant from aluminium salts, namely, aluminium sulphate, aluminium nitrate and polyaluminium chloride (PAC) with the lowest potential for contamination so that their use will minimise pollution from natural dye waste. It also aims to determine the pollution value of natural dye immersion waste from jackfruit wood extract, secang wood, mangsi fruit and several synthetic dyes, to identify potential environmental pollution.

Dyeing with natural dyes was performed by exhaust at room temperature by the pre-mordant method, while with synthetic dyes it was performed by exhaust according to the dyeing procedure (reactive, vat and naphthol). The groundwater, mordant solutions, natural dye extract and the waste-water from the natural and synthetic dyes were then tested to determine their biological oxygen demand (BOD₅), chemical oxygen demand (COD), total suspended solids (TSS), pH, Al and heavy metal contents such as chromium (Cr), copper (Cu), cadmium (Cd), nickel (Ni), cobalt (Co) and lead (Pb).

Aluminium sulphate had the lowest pollution load while PAC had the highest, as aluminium sulphate had a higher BOD₅/COD ratio (0.62–0.67) than aluminium nitrate (0.56–0.64) or PAC (0.44–0.54). The dyeing waste from the three natural dyes contained an acidic pH of 3.5–4.2, Al of 75.280–621.34 mg/L, Cr of 0.154–0.215 mg/L and Cu of 0.035–0.072 mg/L. The values of TSS, COD and BOD₅ are higher than the quality standards of the waste but are environmentally friendly because the ratio of the BOD₅/COD values from the waste ranges from 0.44–0.67.

The findings indicate that as a mordant, aluminium sulphate results in lower pollution loads than aluminium nitrate and PAC. However, all three mordants contain Cr and Cu, albeit in negligible concentrations. Therefore, it is recommended that future studies strive to identify a mordant that has lower pollution loads and does not contain metals but can increase dyeing results to satisfy consumer requirements. It is the hope that, with the discovery of a new mordant, natural dyes will be the solution for the heavy metal pollution caused by synthetic dyes.

The use of environmentally-friendly mordants and natural dyes in the Indonesian textile and batik industry will give rise to superior quality eco-textile and eco-batik products. Such environmentally-friendly and high-quality products will not only increase competition and consumer interest but increase product sales as well which will, in turn, increase incomes and the economy. Additionally, an increase in the use of natural dyes by the textile and batik industry will serve as additional income to the communities and farmers from which the raw materials for the natural dyes are sourced thereby creating jobs and increasing welfare.

As environmentally-friendly mordants and natural dyes replace the hazardous and toxic materials currently used in the textile and batik industry, it guarantees the health and safety of its consumers and workers. Furthermore, as the waste-water produced is biodegradable, it reduces river and groundwater pollution. It is, therefore, expected that this information will not only lead to a shift in attitude within the textile and batik industries but the adoption of environmentally-friendly materials, for the sake of the environment, as well as the development of eco-textile and eco-batik products.

Aluminium sulphate is a mordant type of aluminium salt with a lower potential for contamination than aluminium nitrate and PAC. However, PAC has been discovered to be a mordant for natural dyes, as has the fruit of the mangsi shrub, which has recently been discovered as a naturally occurring blue dye.

The purpose of this study is to assess the attitudes and practices of students and practitioners in the dyeing studio. Empirical evidence shows that synthetic dyes are the most commonly used dyestuff because of their colour fastness as compared with natural dyes. However, it is proven scientifically that synthetic dyes and their auxiliaries are carcinogenic and allergenic, which pose as health risks to users.

The study used analytical observational study design, where observation, questionnaire and interview were the instruments for data collection.

A survey conducted at selected dyeing studios in Ghana revealed the excessive use of vat dyes by students and practitioners because of its availability and accessibility on the local market. Adversely, the study found non-use of personal protective equipment by students and practitioners for protection against hazardous effects of dye chemicals. Again, poor studio set up with limited space and lack of proper waste drainage systems at the various dyeing studios results in inappropriate disposal of dyes, leading to environmental pollution.

Dyeing throughout history has been practiced to colour a fabric or yarn for specific use in the environment, which brings in some revenue. This practice however employs the use of dyes coupled with its auxiliaries, which poses some health problems in the short, medium and long term because of certain attitudes and practices exhibited by students and practitioners in the studio. It is therefore imperative for effective compliance to safety rules and practices by students and practitioners to ensure their safety. It is also critical that educational institutions and practitioners build modern dyeing studios which are spacious, well ventilated and efficient in limiting environmental pollution in compliance with eco-friendly practices. The study further recommends collaboration between Academia, local dyers’ association , Ghana Health Service and the Environmental Protection Agency to organize workshops to ensure best safety practices to save lives and the environment.

Cotton being an anionic fiber can be dyed with direct, reactive, vat and sulfur dyes but cannot be dyed with acid dyes due to their chemical differences. But there are certain advantages of acid dyes like acid dyeing is the simplest method than the other classes of dyes; and it offers various intense and bright shades. So, the purpose of this paper is to focus on acid dyeing of cotton fabric after its chemical modification.

Such modification of cotton fabric has been achieved using poly(amido)amine dendrimer (PAMAM) treatment. The current work is based on the synthesis of a full-generation PAMAM dendrimer (G0) and its application onto the cotton fabric for modifying the cotton substrate by the exhaust and padding method.

The treatment of the dendrimer on cotton fabric has been analyzed by Fourier transform infrared spectroscopy and scanning electron microscopy. The dyeing results in terms of color strength of the treated cotton fabrics are compared with those of conventional acid dyed silk fabric. The fastness assessments such as wash, light and rubbing fastnesses after dyeing of treated cotton fabrics are also performed and found to be satisfactory.

This paper can be used in the application of synthesized poly(amido)amine dendrimer in acid dyeing of cotton.

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.

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.

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.

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.

Dyeing process is usually to blame negatively for deteriorating the environment. Eco-friendly silk fibers are able to exercising their commercial values well followed by eco-friendly processing. One of the supporting examples is the process of changing the colors of silk fabrics. This would include the dyeing process used to change the colors of silk fabric. The intention of the study is to reach the goal of creating an eco-friendly finishing process using a local natural plant-based indigo dyeing process that would complement an eco-friendly degumming process. Currently, most dye houses use sodium hydrosulfite (Na₂S₂O₄) and alkali (NaOH) as the substances for providing hydrogen as a reducing agent. Since the sodium hydroxide by-products are acidic, they may damage equipment in the dye houses, generate air pollution in working environment. The other problems associated with the use of sodium hydrosulfite are the cost and instability with low storage.

This paper is based on continuing improvements to the commercialization of the raw materials via the innovative degumming process elaborated in the author’s previous study: “Degumming of Silk Fibers by CO₂ Supercritical Fluid.” The initial study has already proved that it was possible to remove sericin from raw silk fiber by using an organic acid pretreatment and CO₂ supercritical fluid over the heavy processes the industry currently deploys. The sericin removed from this innovative and eco-friendly processing of silk fiber will be remained in a clean state, not in the form of waste via the existing technologies in use. Clean sericin, rich in silk protein with high market values, can be a potentially perfect substitute of collagen the medical and cosmetic industries widely use. The continued research is focused on the other by-product coming out from this eco-friendly degumming process the silk fibers post degumming. Dyeing process is usually to blame negatively for deteriorating the environment. Eco-friendly silk fibers are able to exercising their commercial values well followed by eco-friendly processing. One of the supporting examples is the process of changing the colors of silk fabrics. This would include the dyeing process used to change the colors of silk fabric. The intention of the study is to reach the goal of creating an eco-friendly finishing process using a local natural plant-based indigo dyeing process that would complement an eco-friendly degumming process.

Degumming is an important stage in the silk manufacturing. Due to removing sericin from silk fibers, when subjected the degumming process, these silk fibers acquire the properties, which are of high consumer and commercial values, those include gloss, perfect color, soft handle and texture, elegant drape. Another purpose for the silk fabric degumming is preparing for the next step in processing, such as dyeing or printing. The author has developed a new approach to the degumming process exploiting a supercritical fluid carbon dioxide and found it as a good alternative to the conventional methods that are currently used in industry. Silk fabrics treated by the scCO₂ degumming process are characterized by improved dyeing ability or color strength, while this process does not adversely affect the environment. The implications or potential applications of the findings: as it is clearly seen from Table 1, the effectiveness of the degumming process can be improved by at least 38% applying scCO₂. Moreover, implementation of the scCO₂ silk degumming process into the textile industry may help manufactures to consume less water and energy resources (Elmaaty and Abd El-Aziz, 2017), as well as to obtain pure sericin as a valuable end-product that can be used in the medical and cosmetic industries.

The innovation and novel aspects of research: degumming is an important stage in the silk manufacturing. Due to removing sericin from silk fibers, when subjected the degumming process, these silk fibers acquire the properties, which are of high consumer and commercial values, those include gloss, perfect color, soft handle and texture, elegant drape. Another purpose for the silk fabric degumming is preparing for the next step in processing, such as dyeing or printing. The author has developed a new approach to the degumming process exploiting a supercritical fluid carbon dioxide and found it as a good alternative to the conventional methods that are currently used in industry. Silk fabrics treated by the scCO₂ degumming process are characterized by improved dyeing ability or color strength, while this process does not adversely affect the environment.

The author has developed a new approach to the degumming process exploiting a supercritical fluid carbon dioxide and found it as a good alternative to the conventional methods that are currently used in industry. Silk fabrics treated by the scCO₂ degumming process are characterized by improved dyeing ability or color strength, while this process does not adversely affect the environment.

As it is clearly seen from Table 1, the effectiveness of the degumming process can be improved by at least 38% applying scCO₂. Moreover, implementation of the scCO₂ silk degumming process into the textile industry may help manufacturers to consume less water and energy resources (Elmaaty and Abd El-Aziz, 2017), as well as to obtain pure sericin as a valuable end-product that can be used in the medical and cosmetic industries.

To make the silk manufacturing more green, the author has developed a technology for obtaining a plant-based indigo dye applying only locally grown agricultural products. The author has found that banana paste and banana peel paste have a sufficiently enough reduction potential for converting the indigo dye into indigo white, which is an important stage in the dyeing processes. The investigation performed showed that both these pastes can serve as a green alternative to sodium hydrosulfite, widely used in industry as a reducing agent. The main result of this study is the demonstration that natural, recyclable and easily biodegradable resources can be exploited to produce the semi-products for the textile industry and the final dyed silk fabrics as well. Summarizing the above, it can be concluded that we have got the results, which show promising alternative green processes for the textile industry in silk treatment (both degumming and dyeing). Their implementation may turn the silk textile production into a sustainable green circle and economically viable manufacturer.

The purpose of this paper is to prepare and characterise various ink formulations for inkjet printing on nylon 66 carpet.

Various ink formulations were prepared using CI Acid Red 57, synthetic thickeners (BYK425 and BYK420), ethylene glycol, diethylene glycol, isopropanol with auxiliaries. The inks were characterised for their rheological, wetting and storage stability properties. The inks were jetted using a Printos P16 drop‐on‐demand jet print‐head onto nylon 66 carpet materials. The printed images were characterised using an ImageXpert system.

It is found that the inks containing the synthetic thickeners at the optimum ratio give good printing and image properties, such as optical density, drop size, and depth of penetration into the substrate at pH 4‐5. The optimised ink formulation is found to have good storage stability.

The study focuses on ink formulations based on CI Acid Red 57. Ink formulations based on other colorants could also be studied in order to assess the applicability of the ink formulation system found for other colorants.

The ink formulations developed could find use in industrial scale printing.

Low cost ink formulations for printing of nylon carpets are novel.

Wherever corrosion occurs it can be the cause of many difficulties and much frustration of effort, but it is believed that in no type of works can corrosion be so wasteful of materials and have so adverse an effect on output as in those works where textile materials are bleached, dyed, printed and finished. This can be readily understood when it is recognised that in the processing of textile yarns, fabrics and garments the results of corrosion not only influence the working of a machine so that this may break down and need repair or replacement, but the products of corrosion may become transferred to the textile material so as to interfere with the desired effects of the processing and thus cause the material to be seriously weakened or acquire some characteristic of colour or handle detrimental to its use or consumer appeal. The following article indicates the complexity of corrosion problems that can occur.

The purpose of this paper is to compare light fastness assessments by exposure of fabric dyes with various dyes in daylight and an artificial xenon arc lamp.

Cotton fabric dyed with 66 reactive, vat, azoic and direct dyes dyed in different depths were exposed to daylight and Xenon arc lamp for assessment of light fastness by standard methods. The light fastness rating and fading hours by the two methods were analysed and compared statistically.

The correlation between the corresponding light fastness rating (LFR) measured in Xenotest and daylight is quite high (0.93). The logarithmic correlation coefficients between fading hour (FH) and LFR in Xenotest and daylight are 0.95 and 0.88, respectively. For Xenotest, the assessed LFRs are same as those predicted from geometric progression up to LFR of 5.5, and thereafter, the former is higher. On the other hand, in the case of daylight, the assessed LFR is lower. Assessments for three successive seasons showed high repeatability in case of Xenotest and moderate repeatability in case of daylight. Assessments for three successive seasons showed high repeatability in case of Xenotest and moderate repeatability in case of daylight.

The exposure conditions in daylight cannot be controlled or standardised, whereas the exposure in Xenon arc lamp in the accelerated fading instrument can be strictly controlled. These differences in exposure control may affect the repeatability of experimental findings.

Inconsistent ratings may be because of little deterioration of samples during storage, as well as seasonal variation of daylight.

There are no direct social implications.

The researches on the comparison of the two light fastness assessment methods have not been reported in any recent publication to the best our knowledge.