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

Natural dyes in textile printing: parameters, methods, and performance

In recent years, consumer preferences have begun to turn back to natural dyes, whereas synthetic dyes have been pushed into the background over the previous 60 years. This is a result of increased knowledge of the potential hazards associated with the creation of synthetic dyes, which use raw materials derived from petrochemicals and involve intense chemical interactions. Such dyes need a lot of energy to produce, and their negative effects on the environment increase pollution. It has been discovered that several of these dyes, particularly the azo-based ones are carcinogenic. On the contrary, natural dyes are getting more attention from scientists and researchers as a result of their several advantages like being eco-friendly, biodegradable and renewable, sustainable, available in nature, having no disposal problems, minimizing the consumption of fossil fuel, anti-bacterial, insect repellent, and anti-allergic, anti-ultraviolet, intensify dyeing and finishing process efficiency, less expensive, and no adverse effects on human health and environment. However, there are also some drawbacks, like poor fastness properties, natural dye printing for bulk production, difficulties in reproducibility of shades, and so forth. Despite all these limitations, the demand for natural dyes is increasing significantly in textile industries because they offer far more safety than synthetic dyes. This study provides an overall concept of the natural dyes in textile printing. It illustrates parameters of printing performance, methods, and techniques of extraction of natural dyes, printing methods, and printing of natural and synthetic fibers. Finally, this study describes the challenges and future prospects of natural dyes in textile printing.

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.

In quest for improvement of dyeing properties using agriculture waste: utilization of Oleaster as new bio-mordant for wool yarns

Agricultural waste is an unwanted material that is not only unmarketable, but also has secondary costs such as environmental pollution. Oleaster, also known as olive Russian fruit, has various uses, but it also produces waste such as seeds and peels. Oleaster fruit and all its parts are tannin rich, which can be utilized as natural mordant. Improvement of fastness and color properties of natural dyed fibers is obtained by using mordant. The employing of this mordant is effective in reducing agricultural waste and the production of dyeing chemical waste. Reseda extract was utilized as natural dye to investigate the color characteristics. The study of the phenolic percentage of different components of the Oleaster fruit, including peel, seed, and flesh, showed that each of these materials can be used as natural mordant. The formation of physical bonds in the presence of all kinds of mordant was investigated using the FTIR method, and the results showed that their performance is similar and they are effective in surface treatment of wool. Investigation of color characteristics of the yarns showed that the color strength increases in the presence of mordant. Studying the fastness of yarns dyed with ISO methods showed that the samples have high washing fastness.

Ultrasonic-assisted sustainable pollution free advanced method for isolation of colouring material from Amba Haldi (Curcuma aromatica) for wool dyeing

The purpose of this research is to evaluate the colouring performance of Amba Haldi-based natural extracted yellowish colour for the dyeing of wool fabric using ultrasonic (US) treatments. Before and after the US treatment, the colourant was separated in aqueous and acidic solutions for up to 60 min. Scanning electron microscopy and Fourier-transform infrared spectroscopy were used to investigate the surface morphology and chemical changes in the cloth before and after radiation. On the wool fabric that was ultrasonically treated at 75°C for 45 min, an acidic extract of Amba Haldi powder after US treatment for 20 min showed good colour depth (K/S). Acacia extract (2%), pomegranate extract (1.5%) and pistachio extract (1%), when used as pre-biomordants, were shown to have excellent colour strength. Acacia (1.5%) extract, pomegranate (2%) extract and pistachio (1.5%) extract were also used as post-biomordants. As pre-chemical mordants, Al salts (1%), Fe salts (1.5%) and tannic acid salts (2%), whereas Al salts (2%), Fe salts (1%) and tannic acid salts (2%), have produced successful results as post-chemical mordants. Overall, it was discovered that pomegranate extract (2%), used as a post-bio-mordant, and salt of Fe (1.5%), used as a post-chemical mordant, both exhibit exceptional colour strength. Ultrasonic treatment, a procedure that is harmless for the environment, has only served to increase the colour strength of dye on wool fabric, and the addition of bio-mordants has made the process more sustainable.

Alkanna tinctoria-based sustainable alkanin natural colorant for eco-dyeing of wool

The awareness of sustainability and widespread utilization of green technologies in textile dye houses are revolutionizing not only textile industries but related fields. The current study is concerned with ultrasonic (US)-assisted utilization of extracts of Alkanna tinctoria (a source of natural alkanin dye) for wool dyeing. The extracts are obtained in various media, and both extracts and wool fabrics have been  US treated for 15-60 min. Dyeing is performed by applying variable parameters and utilizing herbal-based extracts as a source of bio-mordant, hence improving the fastness rating and enhancing color strength. Good color strength and fastness ratings are obtained using irradiated extract at 4 pH when the US-treated wool fabric is dyed at 65 °C for 60 min before and after chemical and bio-mordanting. For comparative studies, chemical mordants are also employed. In contrast to chemical mordants, the bio-mordants have made the dyeing process more sustainable with good to excellent fastness rating.

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.

Assessment of wild turmeric-based eco-friendly yellow natural bio-colorant for dyeing of wool fabric

The current study has been designed to observe the coloring efficacy of wild turmeric-based natural yellowish colorant for wool dyeing under microwave (MW) treatments. Extracts and fabrics have been exposed to MW treatment for up to 10 min. Surface morphology and changes in the fabric's chemical nature before and after radiation have been studied through SEM and FTIR, respectively. The results obtained after a series of experiments show that using 45 mL of aqueous extract (pH = 5) in the presence of 1.5g/100mL of table salt as an exhausting agent at 75°C for 45 min has displayed outstanding color depth (K/S) onto microwave-treated wool fabric. On applying biomordants, it has been found that acacia extract (1.5%), pomegranate (2%), and pistachio extracts (1.5%) before dyeing, whereas acacia (1%), pomegranate (1%), and pistachio extracts (2%) after dyeing, have shown colorfast shades of high strength. Comparatively, salts of Al (1.5%) and Fe (1%), and T.A (2%) before dyeing, while salts of Al (1%) and Fe (1.5%) and T.A (1.5%) after dyeing, have given the best results. Generally, it has been originated that salt of Fe (1.5%) as a post-chemical mordant and pomegranate extract (1.5%) as a post-bio-mordant have displayed wonderful color strength. It very well may be inferred that MW treatment, being naturally protected, has just superior the varying strength of colorants on wool fabric. Adding biomordants has transformed the strategy into a more sustainable one.