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This paper aims to focus on the absorption behaviour of single and binary mixtures of natural dyes on wool. Natural dyes are multi-components with different structures and properties.

In this research, the absorption behaviour of single and binary mixtures of natural dyes was investigated on wool fibre. Study was conducted via some natural dyes, including pomegranate peel as a yellow natural dye with tannin, weld as a yellow natural dye without tannin and madder as a red natural dye without tannin. Applied mordant was alum, which was used in the pre-mordant method. Different shades were obtained by varying dye concentration in the binary mixture. The effect of tannin on absorption behaviour of binary mixture of natural dyes was investigated by spectral reflectance and colour parameters of dyed samples measurements.

Obtained results indicate that tannin affects the absorption behaviour of natural dyes in binary mixtures.

Because natural dyes are multi-components with different structure and properties, the study of compatibility and absorption behaviour of natural dyes in binary mixture on wool is important in applied researches.

The study of compatibility and absorption behaviour of binary mixture of natural dyes on wool is novel.

This work aims to study the effect of mordanting method as pre-mordanting (on-chrome), meta-mordanting (meta-chrome) and post-mordanting (after-chrome) on wool dyeing with madder natural dye without tannin and pomegranates peel, as a natural dye contains tannin.

The woolen yarn was dyed with madder and pomegranate peel natural dyes by three methods as pre-mordant, meta-mordant and pos-mordant. The color parameters and reflectance spectra of dyed samples were analyzed by using derivative spectroscopy and the principal component analysis (PCA) techniques.

The obtained results indicate that the color difference between the samples dyed with madder by pre-mordanting, and the samples dyed by other methods is more than the color difference between the samples dyed by meta-mordanting and post-mordanting. However, the color difference between samples dyed with pomegranate peel by pre-mordanting and meta-mordanting methods is less compared to other pairs. Also, analysis of reflectance spectra and color depth (K/S) values indicate that the color depth of dyed sample with madder by pre-mordanting method is more than other dyeing methods. But, the color depth of sample dyed with pomegranate peel by post-mordanting method is less compared to other methods. The analysis of first-, second-, third- and fourth-order derivatives of reflectance spectra and the study of the first, second, third and fourth PCs of reflectance spectra indicate that the reflectance of dyed samples with madder and pomegranates peel depends on the mordanting method.

Evaluation of the effect of mordanting method on color and reflectance of wool dyed with madder and pomegranates peel natural dyes using derivative spectroscopy and the PCA techniques

In nature, thousands of different colours and shades exist. Basic set of dyes, namely, yellow, red, blue and green are necessary for a complete colour gamut. Creating a complete gamut with natural dyes with one common extraction and application procedure is not exploited hitherto. The paper aims to discuss this issue.

In this study, an attempt was made to create a complete colour gamut with easily available natural dyes with one common extraction and application procedure.

Silk fabrics were dyed using various natural dyes alone and in combination to yield various shades, namely, yellow, red, green, blue. Pre-mordanting of silk fabrics was carried out with mordants, namely, alum, ferrous sulphate, copper sulphate, stannous chloride, potassium dichromate followed by dyeing. The fastness properties and colour strength values of all the shades obtained were determined.

Creating a complete gamut with natural dyes with one common extraction and application procedure is not exploited hitherto.

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.

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 check the effectivity of plasma in the natural dyeing of polyester fabric using four natural dyes – Turkey red, Lac, Turmeric and Catechu using plasma and alum mordant. The surface modification on the polyester fabric by plasma along with the use of benign mordant alum is studied. The enhancement of dyeability in polyester fabric with natural dyes is the main focus. Due to surface modification, the wettability increases, which leads to better dye uptake. Better dye uptake and better dye adherence are the main objectives.

Plasma-mediated natural dyeing is the main design of this research work. The effect of plasma treatment on surface modification of synthetic fabric polyester and its subsequent effects on their dyeing with different natural dyes, namely, Turkey red, Lac, Turmeric and Catechu are studied. The dyeability was further enhanced by the use of alum as mordant. The main focus is on the betterment of natural dyeing of polyester fabric using sustainable natural dyes resources for dyeing and to reduce wastewater contamination from the usage of toxic additive chemicals for cleaner production.

Plasma-mediated and alum-mordanted dyeing method facilitated very good dyeability of all the four natural dyes, namely, Turkey red, Lac, Turmeric and Catechu. Color strength (K/S) values and fastness properties of plasma-treated samples were far better than untreated samples. The synergistic effect of plasma and alum mordanting has made natural dyeing of polyester very easy with very good fastness results. Natural dyeing of polyester after 2 min of plasma treatment showed excellent and desirable results. The process is also easy to be adapted by industries.

As polyester is hydrophobic, natural dyeing of polyester fabric is not very easy, but with plasma-mediated natural dyeing, it becomes a very facile dyeing method; thus, there are no limitations. Use of plasma has reduced the need for any chemical additives which are usually added during the dyeing process.

This process of natural dyeing of polyester fabric can be scaled up to industrial dyeing with natural dyes. Plasma pretreatment of the fabric followed by premordanting with alum has facilitated the natural dyeing well.

Use of plasma in place of chemical modifiers can be a green and environmentally friendly approach for sustainable coloration of polyester fabric, providing a clean wet processing for textiles dyeing.

The synergistic effect of plasma-mediated and alum-mordanted natural dyeing of polyester has not been attempted by any researcher. To the best of the authors’ knowledge, this is for the first time that pretreatment with atmospheric plasma followed by alum mordanting of polyester fabric has shown very good dye uptake and fastness properties as the dye molecules could penetrate well after 2 min of the plasma treatment.

This paper aims to examine the recipe for and standard methods of dyeing cotton fabric with natural dyes from jackfruit wood extract. The dyeing of the fabric was performed by immersion it without heating for a short time to obtain the best results.

The dyeing experiment using cotton fabric with jackfruit wood extract was conducted by immersion at room temperature. The independent variables studied were the mordant method, type of mordant, mordant concentration, salt concentration and dyeing pH. The dependent variables were colour strength and colour fastness to washing and rubbing. The orthogonal array L16 (45) was used in the study to obtain the optimal values for each parameter of the response variables. The multi-response signal-to-noise (MRSN) method was used to optimise the five response variables with different quality characteristics so that the best parameters could be obtained based on the highest MRSN ratio value.

The best parameters were obtained at an MRSN value of 4.5254 under A3B3C1D2E4 conditions, namely, the dyeing process with post mordant, aluminium nitrate type mordant, mordant concentration of 10 g/L, salt concentration of 15 g/L and dyeing a pH: of 10. Under these conditions, the value of K/S was obtained at 1.893, colour fastness to washing (GS: 4) and (SS: 4–5), dry rubbing (SS: 5) and wet rubbing (SS: 4–5).

Obtaining a standard recipe and method for dyeing cotton cloth with jackfruit wood extract by immersion without heating is expected to lead to the development of natural dyes, and especially their application on an industrial scale. This standard and method can be used as technical guidelines by industry. The use of aluminum nitrate as a mordant will help achieve optimal dyeing results. The use of polyaluminium chloride (PAC) mordant, which has the potential to produce high colour strength, and papaya fruit sap, which has the capacity to increase colour fastness, still need to be developed to improve the results of natural dyes.

The standard recipe and dyeing method will be able to improve the results of the dyeing of cotton fabrics with natural dyes. Short immersion dyeing without heating and the optimal results obtained are the main attractions for their use by the textile/batik industry, as the process is easier and a lower cost. The results of dyeing with dark colours and good colour fastness mean the textile products are of the higher quality demanded by consumers, thereby increasing sales. This will encourage the use of and increase the need for natural dyes by industry, consequently reducing the use of synthetic dyes.

The use of natural dyes, chemical mordant from aluminum salts, and natural mordant from papaya fruit sap in the dyeing process in the textile/batik industry in Indonesia will produce eco-textile and eco-batik products that are environmentally friendly and of high quality. This in turn will increase consumer interest and sales, meaning that the income and economy of workers in the textile industry/crafts sector will also increase. In addition, the use of natural dyes with the selection of a safe mordant (not containing heavy metals) will reduce the use of synthetic dyes, which pollute and damage the aquatic environment.

This study found a standard recipe and method of dyeing cotton fabric with natural dyes from jackfruit wood extracted by immersion without heating for a short time to obtain the best results. In addition, the discovery was of PAC, a new mordant which is effective in the use of natural dyes can give high colour strength to cotton fabric. In addition to the discovery of a new mordant, PAC, which has the potential to produce high colour strength, papaya fruit sap also has the capacity to increase colour fastness with the use of natural dyes from the flavonoid group.

Peanut skins are an agro-waste product with no commercial value. The purpose of this paper is to evaluate peanut skin as a natural dyestuff and to determine if this natural dye could be used in the dyeing of some Egyptian cotton cultivars.

The methodology consists of several steps; dye extraction procedure from peanut skin through aqueous extraction, then dyeing optimized using simultaneous mordanting using alum. Finally, dyed cotton has been subjected to different textile laboratory tests, for example, color measurements and mechanical properties. Color-fastness was determined on Egyptian cotton fabric. The peanut skin as a source of natural dye and the dyed cotton sample were characterized by fourier transform infrared spectroscopy (FTIR) analysis.

It was found that the natural dye extracted from peanut skin has an affinity for cotton samples and showed high dyeability with a unique color shade, good color strength and very good fastness.

The novelty of this paper is the extraction of color from the peanut's outer skin which is discarded as waste such as agro-waste of the agricultural process which can be used as a natural dye in the textile industry and applied to dyeing some Egyptian cotton fibers from different genotypes.

The purpose of this paper is to evaluate the efficacy and kinetics along with diffusion properties of a new source of natural dye obtained from leaves and fine stems of the Sesbania aculeata plant, using metallic mordants for cotton dyeing.

The approach followed in this work is to conduct experiments with the application of the natural dye obtained from Sesbania aculeata plant and to study the kinetics, dye uptake and the diffusion properties of this dye.

Sesbania aculeata with simultaneous mordanting with different metal mordants imparted shades which varied from cream to light brown to dark brown in case of aqueous extract. The different mordants used not only changed the hue colour and K/S values but also L* and brightness index values. The results of fastness properties of the dyes were found to vary from fair to good. The percentage dye exhaustion values varied with different mordants. The dye uptake value increased with time and reached its saturation limit after 4 hours of dyeing. In the absence of mordants, the diffusion coefficient values increased with increase in the temperature. In the presence of mordants, the diffusion process appears to slow down, which could be attributed to the binding effects of mordants.

The extraction and dyeing process of Sesbania aculeata plant is less tedious and time consuming compared to the other sources of natural dyes.

Sesbania aculeata is relatively easier to grow and does not require much tending operations. Thus, it promises to be an affordable source of natural dye. If this dye is commercialised, it will help to generate sustainable employment and income for the farmers in rural and sub-urban areas. This could be both for dyeing and for non-food crop farming.

An advantageous feature of this plant, in contrast to the other natural dyes based on vegetable and fruit sources, is that its usage in making the natural dye does not result in any wastage of an otherwise highly commercial product. The current experimental study on a new source of natural dye would be a significant contribution to the existing database of knowledge regarding the kinetics and diffusion properties of natural dyes. There are several reported studies in the literature pertaining to the application of natural colourants and evaluation of their dyeing properties on various fibers. However, relatively fewer studies exist on the kinetic and exhaustion aspects. Thus, the current study would help to develop a set of predictable settings for application of natural dyes on various textiles.

Commercial natural dyes are quite costly as manufacturers are to follow multi-step extraction and purification procedures for standardisation purposes. Upon cost comparison, they lose in the market to synthetic dyes. However, in the handicraft sector, reproducibility may be of lesser importance against cost. In the present study, a domestic method of dyeing silk with the aqueous extract of raw plant/tree components (flower, leave, bark and root) by using a natural mordant and alum will be described. Good dyebath exhaustion and washing and light fastness are observed for some of the natural colouring matters.