Search results

The precise and sensitive methods for authentication and differentiation of natural and synthetic indigo dyes are required for assurance of textile safety and public health. This study aims to develop a fast and simple method to distinguish natural indigo from synthetic one.

A static headspace gas chromatography-mass spectrometry (GC-MS) method was developed for identification of natural and synthetic indigo samples. Natural indigo samples prepared from three different plants and synthetic indigo samples from three famous manufacturers in China, were involved in this study, along with some nonindigo blue samples (such as direct blue, active blue and neutral blue). The yarns and fabrics dyed with natural and synthetic indigo were also analyzed by the GC-MS method.

High levels of aniline (21.87%–71.59%) or N-methylaniline (25.26%–38.73%) were detected only in synthetic indigo samples (1 g) using the static headspace GC-MS method. The yarns and fabrics dyed with the synthetic indigo were also detected with residual aniline (0.47%–14.86%) or N-methylaniline (6.59%–40.93%).

The results clearly demonstrated that aniline or N-methylaniline can be used a diagnostic marker for distinguishing natural indigo from synthetic indigo. The proposed static headspace GC-MS method is a rapid, simple and convenient approach for differentiation of natural and synthetic indigo, as well as for the yarns and fabrics dyed with synthetic indigo.

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.

An indirect electrochemical reduction and dyeing with indigo were carried out here to solve problems of low dye reduction rate and poor dyeing depth in the current electrochemical dyeing process.

Response surface analysis tests were performed to evaluate the effects of ferrous sulfate concentration, medium concentration, sodium hydroxide concentration and reduction time on the reduction efficiency of indirect electrochemical reduction of indigo.

The conditions obtained by design-expert optimization showed that the concentration of FeSO₄·7H₂O has the most significant effect on the reduction performance of dye liquor. Under the optimized electrochemical reduction dyeing process, the rate of dye reduction could be reached 91.21 per cent and the K/S value of indirect electrochemical dyeing of indigo can be achieved to 12.96, which is increased by about 9.56 per cent compared with that of Na₂S₂O₄ dyeing with the same color fastness basically.

The recyclability and biodegradability of the dye remain to be explored.

The strategy presented here can be developed to replace a substantial part of electrochemical dyeing with optimized product quality and reduced environmental pollution in denim production.

The strategy presented here can be developed to replace a substantial part of electrochemical dyeing with optimized product quality and reduced environmental pollution in denim production.

Application of the Fe(II)-DGS-Abal B complex media system in the indirect electrochemical reduction of indigo.

The purpose of this study is to investigate the physical, ultraviolet (UV), colour appearance and colour fastness properties of selected fabrics dyed with natural dyes from Daboya and Ntonso communities of Ghana. The study further highlights the rich cultural heritage of traditional dyeing from these two communities. Craftsmen in West Africa especially Ghana, have sustained the traditional dyeing methods to produce textile products for consumers.

In this study, two sample fabrics were purchased from craftsmen at Ntonso and Daboya communities in Ghana. These fabrics were analysed at the laboratory under standard test methods for their physical, UV, colour appearance and colour fastness properties.

Results showed that all the sample fabrics have good UV shielding performance (ratings above 50+). Daboya sample fabrics (dyed with indigo dyes) produced more colour stains than the sample fabrics from Ntonso (dyed with black “kuntunkuni” dyes). The K/S_sum value or colour yield reduced after washing but that alternatively increased the calculated ultraviolet protection factor.

Findings from this study exposed the unique UV performance of dyed traditional fabrics (using natural dyes) from Ntonso and Daboya communities in Ghana. This inspires and enforces the need for craftsmen to improve their production cycle to produce these fabrics in different sizes which provides the necessary UV shielding abilities for consumers in the wake of climate changes.

This study demonstrated that the natural dyeing process at the two communities produced relatively good UV and colour fastness properties of the sample fabrics. These eco-friendly dyeing practices have survived over time to maintain and promote the concept of sustainability within the textile and fashion industry in Ghana.

In the denim industry, enzyme washing and its combination with stone washing are generally used to get the desired worn-out look. However, these conventional methods include high water, energy and time consumption. Nowadays, laser fading, which is a computer-controlled, dry, ecological finishing method, is preferred in the denim fading process. The purpose of this study is to observe the effects of chemical pretreatment applications on laser-faded denim fabric in terms of color and mechanical properties. To eliminate the enzyme washing process in denim fading and to minimize the disadvantages of laser fading, such as decreased mechanical properties and increased fabric yellowness, various chemical pretreatment applications were applied to the denim fabric before laser fading, followed by simple rinsing instead of enzyme washing.

Two different indigo-dyed, organic cotton denim fabrics with different unit weights were exposed to pretreatment processes and then laser treatment, followed by simple rinsing. Polysilicic acid, boric acid, borax and bicarbonate were used for pretreatment processes, and laser treatment was carried out under optimized laser parameters (40 dpi resolution and 300 µs pixel time). Tensile strength was tested, and color values (CIE L*, a*, b*, ΔE*, C* and h), color yield (K/S), yellowness and whiteness indexes were measured to identify the color differences.

Before laser fading, 30 g/L and 40 g/L polysilicic acid pretreatments for sulfur-indigo-dyed fabric and a mixture of 10 g/L boric acid and 10 g/L borax pretreatments for the fabric only indigo-dyed were recommended for the laser fading with sufficient mechanical properties and good color values.

With the chemical pretreatments defined in this study, it was possible to reduce yellowness and maintain the mechanical properties after laser fading, thus minimizing the disadvantages of laser treatment and also eliminating enzyme washing.

The purpose of this paper is to describe the role of women in rural communities of South‐Western Nigeria in entrepreneurial engagement through craft practice.

Literatures were reviewed on crafts practice and appreciation in Nigeria. This enabled the contemplation of the place of craft practice as occupational engagement before, during and post colonial periods. The process of data gathering consists of field work, interviews, observation and photographing; through this, the technical production of mat and indigo dyed fabric were explored.

Women of rural communities in Western Nigeria have been actively been involved in crafts production to make ends meet in a male dominated economy. They form professional guilds to revive craft production/patronage, to network among members, and to seek help from the government and relevant organizations. The study found out that the potentials of the rural women can be fully developed if the method of making their products is given a facelift through partial mechanization.

An average Nigerian wants to be employed in white collar job and people are no longer interested in craft practice. The apprenticeship system of learning in the traditional system whereby skill is transferred from parents to their children is almost becoming a history. Thus, craft production is in the hand of few people among which the rural women are very spectacular.

This paper considers the women of rural communities in Southwestern Nigeria as a factor in the revilitalization of traditional crafts through occupational engagement in craft practice.

Everyone is extremely concerned about environmental protection and health safety due to the rise in living standards. Plant-derived natural dyes have garnered much industrial attention in food, pharmaceutical, textile, cosmetics, etc. owing to their health and environmental benefits. The present study aims to focus on the elimination of the use of synthetic dyes and provides brief information about natural dyes, their sources, extraction procedures with characterization and various advantages and disadvantages.

In producing natural colors, extraction and purification are essential steps. Various conventional methods used till date have a low yield, as these consume a lot of solvent volume, time, labor and energy or may destroy the coloring behavior of the actual molecules. The establishment of proper characterization and certification protocols for natural dyes would improve the yielding of natural dyes and benefit both producers and users.

However, scientists have found modern extraction methods to obtain maximum color yield. They are also modifying the fabric surface to appraise its uptake behavior of color. Various extraction techniques such as solvent, aqueous, enzymatic and fermentation and extraction with microwave or ultrasonic energy, supercritical fluid extraction and alkaline or acid extraction are currently available for these natural dyes and are summarized in the present review article.

If natural dye availability can be increased by the different extraction measures and the cost of purified dyes can be brought down with a proper certification mechanism, there is a wide scope for the adoption of these dyes by small-scale dyeing units.

The purpose of this study is to extract and characterize a novel natural dye from the leaves of Lannea coromandelica and the extraction with finding ways of dyeing cotton fabric using three mordants.

The colouring agents were extracted from the leaves of Lannea coromandelica using an aqueous extraction method. The extract was characterized using analysis methods of pH, gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared (FTIR), ultraviolet-visible (UV-vis) and cyclic voltammetry measurement. The extract was applied to cotton fabric samples using a non-mordant and three mordants under the two mordanting methods. The dyeing performance of the extracted colouring agent was evaluated using colour fastness properties, colour strength (K/S) and colour space (CIE Lab).

The aqueous dye extract showed reddish-brown colour, and its pH was 5.94. The GC-MS analysis revealed that the dye extract from the leaves of Lannea coromandelica contained active chemical compounds. The UV-vis and FTIR analyses found that groups influenced the reddish-brown colour of the dye extraction. The cyclic voltammetry measurements discovered the electrochemical properties of the dye extraction. The mordanted fabric samples showed better colour fastness properties than the non-mordanted fabric sample. The K/S and CIE Lab results indicate that the cotton fabric samples dyed with mordants showed more significant dye affinities than non-mordanted fabric samples.

Researchers have never discovered that the Lannea coromandelica leaf extract is a natural dye for cotton fabric dyeing. The findings of this study showed that natural dyes extracted from Lannea coromandelica leaf could be an efficient colouring agent for use in cotton fabric.