Recent advances in the surface modification strategies to improve functional finishing of cotton with natural colourants - A review

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

Sustainability in all applied fields particularly in textiles is to protect our globe, environment, and community, where green dyed products are playing their role. For the current study, Esfand (Peganum harmala) has been explored using a green isolation tool, i.e., ultrasonic (U.S.) rays, and applied onto fabric. Different dyeing parameters have been explored statistically through response surface methodology by employing temperature (50-80°C), time (25-65 min), extract volume (15-55 mL), salt (1-5 g/100 mL), and dye bath pH (4-7) through series of experiments. For developing new shades, green mordants such as elaichi, neem, turmeric, and zeera have been utilized. It has been found that exposure of 35 mL extract of 7 pH containing 3 g/100 mL of salt as exhausting agent to U.S. rays for 30 min for the dyeing of silk at 70°C for 45 min has given maximum color strength with reddish-yellow shades. Color characteristics obtained in the CIE Lab system reveal that 5% of turmeric as meta bio-mordant has given good quality reddish-yellow shades. It is found that U.S. rays have not only good potential to isolate colorant followed by dyeing of silk under reduced condition but also the application of bio-mordants have made the process more greener, sustainable, and cleaner.

Eco-friendly approach towards isolation of colorant from Esfand for bio-mordanted 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.

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

Sustainable natural coloring potential of bitter gourd (Momordica charantia L.) residues for cotton dyeing: innovative approach towards textile industry

Textile coloration using synthetic dyes is not eco-friendly and has detrimental impact on wearer skin. Hence, natural dye is assumed as a suitable alternative for sustainable textile manufacturing and coloration. In this study, we utilized Turmeric (Curcuma longa L.) extract for cotton fabric dyeing. Additionally, biomordants (derived from Citrus lemon and Colocasia esculenta bulk) and metallic mordants (Potassium dichromate and Potash alum) pre-treatments were carried out to upturn the overall uptake of dyes into the fabric interior. The resulted color-strength (K/S) of biomordant pretreated sample was two times higher (K/S=8.6) than the metal mordanted sample (K/S=4.0). To investigate the fastness properties of dyed fabric varities, colorfastness to rub (dry and wet), wash, water, and perspiration test were performed and found superior result for bio-crosslinkers compared to metallic salts chelation. Futhermore, the visual uniformity and moisture absorption on the hue (h*) by the final dyed samples were also found excellent in both mordanted dyed fabrics. Thereby, this dyeing process propossed the viability of natural dyestuff with synthetic auxiliaries for facile cotton fabric coloration. Therefore, the utilization of Turmeric extract as a usefull dye source and Citrus lemon, Colocasia esculenta bulk extract as biomordant could reckon a positive insight for cleaner textile manufacturing and dyeing.

Md. Fazla Rabbi

Papers

Effect of turmeric dye and biomordants on knitted cotton fabric coloration: A promising alternative to metallic mordanting