Microwave-assisted sustainable exploration of cocklebur leaves (Xanthium strumarium L.) as a novel source of distinct yellow natural colorant for dyeing cotton fabric.

During current times, the use of bio-colorants attained public acceptance as a sustainable alternative to synthetic ones which in turn reduced the environmental contamination. The present study focused on the green, safe, and clean technology for the resurgence of natural colorant from cocklebur (Xanthium strumarium L.) leaves and their application to cotton fabric. Natural colorants were extracted by employing an eco-friendly microwave-assisted extraction process using an aqueous and alkaline medium. Dyeing of cotton fabric was carried out using irradiated and unirradiated cotton fabric with irradiated and unirradiated natural dyes of cocklebur leaves. The results of extraction experiments revealed that 4 min microwave-assisted alkaline extract exhibited significantly outstanding color strength onto microwave-treated cotton fabric compared to aqueous one. Further to investigate the optimum dyeing conditions for cotton fabric, various dyeing variables such as dyeing time, dyeing temperature, dye concentration, and exhausting agent were monitored and found a superior result using a dye concentration of 45 ml, for dyeing cotton fabric at 75 °C for 50 min in the presence of 4 g/100 ml of table salt. For improvement in color strength and color fastness properties, the effects of various bio-mordants, such as eucalyptus bark, acacia bark, turmeric rhizome, and onion shells, and chemical mordants (aluminum and copper) on dyed cotton fabric were also evaluated. It was also observed that cotton fabric dyed with alkaline extract of cocklebur leaves using bio-mordants as pre-mordants (4% acacia, 4% eucalyptus, 2% onion) and post-mordants (3% onion, 3% eucalyptus, 4% acacia) exhibited the highest color strength and various hues with acceptable colorfastness properties against light, washing, and rubbing in comparison to chemical mordants. The ISO standard for fastness also revealed that bio-mordanting has enhanced the rating from good to excellent in comparison to chemical mordants. The results provide ample scope for the extraction of yellow natural dye from the cocklebur leaves for eco-friendly coloration of fabrics using bio-mordants.

Environmental friendly pollution free bio-dyeing of wool with haar singhar (Coral Jasmine) flower extract.

The world's move towards revival of eco-labelled products has created a huge urge to explore new means which are healthier for the global community. Among such means, plant-based bio-pigments for coloration of matrix are gaining worldwide fame, particularly in the textile sector. For the purpose of appraising new source of eco-friendly dyes, using microwave irradiation techniques, Coral Jasmine flowers have been explored for the bio-dyeing of wool. The colorant was extracted in acidic medium owing to nature of fabric, and both stuffs have been exposed to microwave treatment up to 5 min. Bio-coloration of MW irradiated and unirradiated wool was done using MW irradiated and unirradiated extract for observing high yield. Central composite design (CCD) as statistical method was utilized to see the significance of dyeing parameters chosen for mordanting to develop colorfast shades. Different concentrations of sustainable chemicals and bio-mordants as per weight of fabric were employed to introduce new shades with improved colorfastness properties. International standard textile methods determining shade permanency (fastness) have been employed onto selected dyed-mordanted fabrics. Good yield of colorant was observed when MW irradiated wool fabric was dyed at 75 °C for 45 min with extract of 7 pH, having 1.5g/100 mL of salt solution; the promising color yield was observed. As per gray scale ratings observed after ISO standard methods, pine nut as bio-mordant and iron salt as chemical mordant have developed colorfast shades. Conclusively, it can be recommended that methods for the isolation of colorants from new dye yielding plants, MW heating method as suitable clean technology and medicinal-based bio-mordants should be employed for getting permanent gamutes.

Ecofriendly application of coconut coir (Cocos nucifera) extract for silk dyeing.

The worldwide resurgence of natural dyes in all fields is due to the carcinogenic effects of effluent loads shed by synthetic industries. Coconut coir (Cocos nucifera) containing tannin as a source of natural colorants has been selected for coloration of bio-mordanted silk under the influence of ultrasonic radiations at various dyeing conditions. For extraction of tannin dye from cocos powder, different media were employed, and dyeing variables such as dyeing time, dye bath pH, dyeing bath temperature, and the effect of salts on dyeing were optimized. For achieving new shades with excellent color characteristics, bio-mordants in comparison with chemical mordants were employed. It has been found that acid-solubilized extract after ultrasonic treatment for 45 min has yielded high color strength, when coconut coir extract of 4 pH from 6g of cocos powder, containing 5g/100mL salt solution as exhaust agent, was used to dye silk at 75°C for 65 min. Among bio-mordants turmeric (K/S=13.828) and among chemical mordants iron has shown excellent results (K/S=2.0856). Physiochemical analysis of fabric before and after US treatment shows that there is no change in the chemical structure of the fabric. It is found that ultrasonic waves have excellent potential to isolate the colorant followed by dyeing and environmental friendly mordanting at optimal conditions, but also the usage of herbal-based plant anchors, i.e., bio-mordants, has made the natural dyeing process more sustainable and clean.