Cleaner colorant extraction and environmentally wool dyeing using oak as eco-friendly mordant

Bio-mordants: a review

Due to the increasing pressure on environmentally friendly approaches and sustainable production processes, the textile dyeing industry has focused on natural colorants. Thus, the use of bio-mordants, which are biological materials, has become widespread as an alternative to metal salts, most of which are non-ecological, used in the application processes of natural colorants. In natural dyeing, dyers want to use mordant substances in the dyeing processes in order to both expand the color spectrum and improve the fastness properties. Conventional metal salts used in natural dyeing are made up of metallic ions, which, when released into the environment as wastewater effluent at the end of the dyeing process, cause major damage to the ecosystem. Many researchers have thought about using mordants derived from natural sources to address the environmental problem. This article is a review of the investigation of natural mordants used instead of metallic mordants in the process of coloring various textile materials with natural dyestuff sources. It has been determined that many substances, most of them herbal materials, are used as mordants. In this review, mordants, except for conventional metal salts, are examined under three main groups for a better understanding. These groups are as follows: (i) natural or bio-mordants, (ii) oil mordants, and (iii) new-generation and non-vegetable-based mordants. Here, researchers will find an overview of the most recent developments in green mordants as well as application techniques for a variety of mordants.

Sustainable appraisal of lac (Kerria Lacca) based anthraquinone natural dye for chemical and bio-mordanted viscose and silk dyeing

The coloring behavior of laccaic acid, a natural red dye derived from lac insects, has been investigated in this work for the dyeing of silk and viscose fabrics while being heated in MW radiation. The extract was made in an aqueous and acidic media and then used to color fabrics under microwave treatment for up to 10 min. For developing new shades, eco-friendly green bio-mordants and, in comparison, chemical mordants were employed at given conditions. The obtained results revealed that the aqueous extract after 4 min of radiation exposure produced a high color strength (K/S  =  17.132) onto silk and the aqueous extract after 6 min of radiation exposure produced better color strength (K/S  =  6.542) onto viscose at selected conditions. The fastness ratings evaluation as per ISO standards demonstrates that bio-anchors have provided good ratings under selected irradiation and dyeing conditions. It is concluded that this environmentally friendly technique has improved the natural coloration process of fabrics as well as addition of green mordants has furnished colorfast shades using lac-derived natural anthraquinone dye.

Anar Phali (Opuntia ficus) juice extract as a novel pollution-free source of natural betalain dye for wool yarn

Green products such as plant pigments in all filed are gaining fame globally due to their excellent ayurvedic and biological characteristics. In this study, microwave rays have been employed for the isolation of colorants from Anar Phali while bio-mordant have been included to get color-fast shades. The colorant was isolated in an acidic medium before and after microwave rays for 2 min. For getting darker shades with different tints, sustainable chemical and plant-based extracts as bio-mordant have been employed before and after bio coloration of wool yarn at given conditions. CIE Lab system computed in Colori-spectrophotometer (CS-410) was used to observe the change in color depth and tonal variation of dyed fabrics, and ISO standard methods have been employed to rate the colorfastness to light, washing, and rubbing at grey scale. It is concluded that microwave rays have an excellent sustainable efficacy to isolate colorant from Anar Phali powder for wool dyeing, whereas the addition of bio-mordants has made the process more sustainable and eco-friendly.

Dyeing of polyamide 6 fabric with new bio-colorant and bio-mordants

The present study investigates the natural dyeing of nylon fabric using the dragon's blood resin extract. Response surface methodology was used to optimize the process variables including pH (3-9), temperature (50-100 °C), concentration (10-50%owf), and time (30-90 min). From a visual point of view, diverse eco-friendly shades with a rather diverse color gamut of varied hue and tone were generated by applying a wide range of natural and eco-label mordants. The impact of 4 bio-mordants (including peppermint, mugworts (Artemisia), Dorema ammoniacum (DA) gum, and pomegranate rind), as well as 4 mineral mordants (alum, copper (II) sulfate, potassium dichromate, and iron (II) sulfate) on the color and fastness properties of the dyed nylon samples, was assessed. The concentration of the used mordants was 5%owf, and the dyeing experiments were conducted by applying the pre-mordanting technique. Measurement of the color strength (K/S) of the dyed fabric was done using a reflectance spectrophotometer. The dyed nylon fastness qualities and the colorimetric characteristics were then evaluated by applying the related standards. The results showed that the optimum conditions for obtaining the highest color strength were dye concentration = 50%owf, pH = 6, temperature = 100 °C, and dyeing tome = 60 min. The proposed ISO standards in relation to colorfastness displayed acceptable ratings for the color strength of dragon's blood resin dyed fabric while its treatment was done by applying bio-mordants in comparison to its metallic counterparts. Therefore, dragon's blood resin could be regarded as a promising eco-friendly natural colorant source for the purpose of sustainable nylon dyeing.

Environmental friendly silk and cotton dyeing using natural colorant of Bougainvillea (Bougainvillea glabra) flowers: the sustainable approach towards textile industry

For the current study, Bougainvillea flowers as environment friendly sustainable source of plant-based natural dye have been selected as an alternative to toxic synthetic dyes for dyeing of cotton and silk. Natural colorant from Bougainvillea flowers (Bougainvillea glabra) was extracted using aqueous and acidic extraction media. Maximum colorant was extracted in aqueous medium, and further it was used for cotton and silk dyeing. The optimum values of the dyeing parameters including dyeing time, dye to liquor ratio and salt level as exhausting agent were found to be 30 min, 35-mL liquor ratio and 3.0 g for cotton and for silk 45 min dyeing time, 45-mL liquor ratio and 3.0 g exhausting agent in aqueous dye extract. Bio mordanting has been applied to attain a variety of color shades. The utilization of 3% of henna, 4% of turmeric for silk pre-mordanting and for post-mordanting turmeric at 3% and henna at 4% for silk gave a darker shade. For cotton bio mordanting, 2% turmeric rhizome powder, 3% henna leaves powder extract as pre-mordant and 2% turmeric, 3% henna as post-mordant has developed a variety of shade. Overall, it has been found that natural colorant from Bougainvillea flowers is the new dye source for bio-coloration of natural fabrics, and addition of bio mordants has made the process more calming and eco-friendly.

Sustainable application of novel herbs on cotton fabrics as biomordants and colourants

The textile industry is ambitiously parading towards circularity and curtailing its dependency on fossil fuels hence the instigated research that adheres to Sustainable Developmental Goals (SDGs) and benefits the environment and human health alike. The current research experimented with innovative sources of plant-based biomaterials namely dandelion leaves, bilberry leaves, nettle leaves, and violet herb for application on cotton fabric as biomordants and colourants. The AAS analysis of mild 6% herbal solution revealed ferrous content of 6.78 mg/l in violet herb and 5.03 mg/l of the copper content in dandelion leaves applicable on cotton fabrics as biomordants thereby preventing the depletion of copper and ferrous elements mineral ores. A fair lightfastness rating and good to very good wash and rub fastness test results were obtained individually. The maximum K/S value of 13.95 was gained on cotton fabrics treated with a mild herbal infusion of bilberry leaves and coloured with violet herbs. The ATR-FTIR peak analysis noted strong = C-H bend of alkenes, strong C = O stretch of α and β unsaturated esters, and strong C-O stretch of carboxylic acids functional groups in raw herbs and its treated cotton fabrics. The dissolved oxygen (DO), oxidation-reduction potential (ORP), and potential of Hydrogen (pH) values were found in the acceptable range for all the spent solutions left after colouration of cotton fabrics with violet herbs hence sustainable. The data set obtained was statistically validated with ANOVA one-way test. Life cycle analysis and clinical investigation on potential therapeutic benefits of herbal fabrics to the wearer are suggested for future research and development.

Green miles in dyeing technology: metal-rich pumpkin extracts in aid of natural dyes

To reduce environmental pollution, it is essential to use green processes in dyeing and meet its requirements. Most natural dyes have a low affinity to be used in the dyeing process. To refine this limitation, the mordanting flow is necessary for many dyeing cases. Pumpkin extract as a natural, metal-rich source can be used as a bio-mordant in green dyeing of natural yarns such as wool. Two natural dyes native to Iran, Reseda luteola and madder, were employed in this study. The effectiveness of bio-mordant presence on yarns was evaluated by FTIR-ATR test from mordanted and mordanted-dyed wool samples. The study of K/S (color strength) content of dyed samples showed that increasing the dye concentration increases the amount of K/S. Fastness performance of wool dyed with pumpkin alternated from good to excellent depending on natural dye type and concentration, due to the formation of complex structures.

Microwave-Assisted Exploration of Yellow Natural Dyes for Nylon Fabric

Today, the global community is appreciating green technologies in the application of green products in textiles. The aim of the current study is to use a sustainable heating technique for the isolation of colorant from plant sources and to use eco-friendly anchors to improve the fastness of dyed fabrics with new shades. The current study used microwave radiation to isolate natural colorants from saffron (Crocus sativus) and safflower (Carthamus tinctorius L.) petals for polyamide (nylon) fabric dyeing. For this purpose, acidic extract and fabric were exposed to MW treatment for up to 6 min and employed at various conditions. To make the dyeing process sustainable, bio-mordants have been employed and compared with synthetic mordants. It has been found that 6 min is the optimal radiation time for the isolation of colorant to get good results onto irradiated polyamide (nylon) fabric when employed at 65 °C for 45 min containing 1 g/100 mL of table salt for saffron and 3 g/100 mL of table salt for safflower dyeing. For improving color strength and giving an acceptable rating of fastness, 7% of turmeric as a pre-bio mordant and 7% pomegranate as a post-mordant has given high results using saffron extract. Similarly, with safflower extract, 5% of turmeric as a pre-mordant and 5% of turmeric extracts as a post-mordant have given high results as compared to chemical mordants used. It is concluded that microwave treatment has a high potential for investigating the coloring efficacy of crocin-containing saffron petals and safflower petals as carthamin as a yellow natural dye for bio-mordanted polyamide fabrics. It is recommended that such tools for the isolation of colorant from new dye-producing plants should be used, whereas green mordants should be used to develop new colorfast shades to make process more green and sustainable.

Environmental-friendly extraction of Peepal (Ficus Religiosa) bark-based reddish brown tannin natural dye for silk coloration

The present study aims to extract a natural reddish brown colorant from Peepal (Ficus religiosa) for silk dyeing using the microwave radiation process (MW). The colorant was isolated in aqueous and acidic media, and MW treatment for 1, 2, 3, 4, and 5 min has been given to both fabric and extract to observe changes in color intensity. The dye variables have been optimized, and for sustainable shade making process with good fastness, 1.0-5.0 g/100 mL of sustainable chemical and bio-mordants has been employed. It has been found that after microwave treatment for 3 min, under selected conditions, the irradiated aqueous extract has given high color intensity onto silk fabric. The utilization of 3% of Al, 4% of Fe, and 2% of tannic acid (T.A.) as pre chemical mordant whereas 4% of Al, 4% of Fe, and 3% of tannic acid as post chemical mordant have given good color characteristics. In comparison, 4% of acacia and 3% of turmeric and pomegranate while 3% of acacia and turmeric and 4% of pomegranate extracts as post-bio-mordant have given excellent color characteristics. It is concluded that MW treatment has an excellent sustainable efficacy to isolate colorant from Peepal bark for silk dyeing, whereas the inclusion of bio-mordants has not only made the process more sustainable and environmental friendly but also best K/S, and L*a*b* values have been acquired.

Sustainable isolation of licorice (Glycyrrhiza glabra L.)-based yellow natural colorant for dyeing of bio-mordanted cotton

Sustainability in the utilization of products in all fields particularly food textiles, solar cells, etc. is of prime concern to the global community. In this study, licorice (Glycyrrhiza glabra L.) as a source of herbal-based coloring agent for cotton dyeing has been explored under the influence of ultrasonic (US) waves. Methanolic extract of licorice bark after US treatment for 20 min has shown excellent color depth (K/S) onto ultrasonically treated cotton fabric at 65°Cfor 45 min. Applying bio-mordants, it has been found that acacia extract (1%), henna (5%), and pomegranate and turmeric extracts (7%) as pre-bio-mordant, whereas acacia, turmeric, and henna extracts (7%) and pomegranate extract (5%) as post-bio-mordants, exhibited superb color strength. Salts of Al (7%) and salts of Fe (3%) as pre chemical mordants, while salts of Al (3%) and salts of Fe (5%) as post chemical mordants, have given good results. Overall, it has been found that salt of Fe (3%) as pre-chemical mordant and extract of turmeric (7%) as post bio-mordant have shown superb color strength. It can be concluded that US treatment being an environmentally safe means has only improved the color strength of colorant onto cotton fabric and the adding of bio-mordants has contrived the method more sustainable.

Waste black tea leaves (Camelia sinensis) as a sustainable source of tannin natural colorant for bio-treated silk dyeing

Environmentally friendly products are the need of the hour, particularly in this pandemic situation because synthetic products need such toxic chemicals for their formulation and finishing which are carcinogenic for the globe. The current study is the utilization of waste black tea leaf (BT)-based tannin brown natural colorant for silk dyeing using microwave treatment. Dye (tannin) has been isolated in various media before and after microwave treatment up to 6 min and applied at various conditions. It has been found that 30 mL of aqueous extract of 3.0 pH obtained from 6.0 g of powder containing 3.0 g/100 mL of salt as an exhausting agent after microwave treatment for 5 min, when employed at 55 °C for 45 min, has given good color yield onto silk. Iron (3%) and acacia extract (2%) as pre-chemical and bio mordant, iron (2%) and pomegranate extract (2%) as post chemical and bio-mordant, and Al (3 %) and pomegranate extract (3%) as meta chemical and bio-mordant have given new shades with good to excellent fastness ratings. It is inferred that waste black tea leaves (BTs) in an aqueous medium have an excellent potential to serve as a source of natural tannin brown dye for the coloration of surface-modified silk fabrics under the influence of cost, energy, and time-effective microwave treatment. Additionally, the utilization of a low amount of sustainable chemical and bio-mordants has valorized the dyeing of silk by developing soothing and sustainable shades with good fastness properties.

Sustainable application of Cassia obovata-based chrysophanic acid as potential source of yellow natural colorant for textile dyeing

In the current pandemic scenario, sustainable green products particularly antiviral, antioxidant, and antibacterial in nature are gaining worldwide fame in almost every walk of life. Cassia obovata (C. obovata) has been valorized as a source of yellow natural dye for nylon dyeing. For the isolation of dye extracts and for surface tuning, nylon fabrics were treated with microwave rays up to 10 min. For getting new shades with good to excellent fastness characteristics, sustainable bio-mordants in comparison with chemical mordants have been used at 60 °C, 70 °C, and 80°C. It has been found that for getting effective colorant yield, acidic extract should be exposed to MW ray treatment up to 6 min, and for getting improved fastness rating, bio-mordants have given excellent color characteristics. Statistical optimization of dyeing variable shows that application of 40 mL of C. obovata acidic extract of RE of 6 pH containing 3 g/100 mL of salt when employed at 55 °C for 45 min has given excellent results onto irradiated nylon fabric (RNF). It is inferred that Cassia obovata has an excellent potential for coloration of surface-modified fabrics, where the application of low amount of bio-mordants under statistical optimized conditions has made process more ecological, economical, and sustainable.