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.

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

UV-blocking cotton fabric design for comfortable summer wears: factors, durability and nanomaterials

Plant tannin and chitosan-templated cellulose for improved absorption of UV protective natural chromophores

Purpose In recent years, natural dyes have attracted significant attention globally because of growing public awareness of the environment and health hazards associated with synthetic dyes. Natural dyes can provide special aesthetic qualities as well as the ethical significance of a product which is environmentally friendly. By keeping this burning issue in mind, this study aims to explore the dyeing properties of various unexplored environmentally friendly natural dyes. Design/methodology/approach In this study, the aqueous extract of coconut leaves is used for dyeing purpose. The silk and jute fabrics were dyed with the extract alone as well as in combination with metal salts as mordants by employing pre-, meta- and postmordanting techniques. The dyeing properties of the colored samples were evaluated by measuring their color strength; CIE L * a * b * values; and color fastness to washing, light and rubbing. Findings A yellow shade was achieved when the fabric samples were dyed solely with the extract. However, shade variations were observed when different mordants and mordanting techniques were applied. In all the cases, metallic salts improved the color fastness properties of dyed samples to washing, light and rubbing especially for the silk fabric. Originality/value To the best of the authors’ knowledge, this is the first report on a natural dye extracted from the leaves of coconut. Leaf as the source of dye has added an extra advantage, as it is reproducible and can be collected easily without harming the plants. The reported dye could be an attractive choice for sustainable and eco-friendly dyeing. 

Natural dyeing of silk and jute fabric with the aqueous extract of coconut leaves – an eco-friendly approach

Natural dyes play an important role in sustainable dyeing processes. However, natural yellow dyes with good performance are rare. Traditional natural yellow dyes have issues, such as a narrow color range and poor light fastness. In this paper, a new natural yellow dye was extracted from a low-cost herb Geranium caespitosum L. (G. caespitosum). In addition, the dye composition was analyzed using UV-visible spectroscopy. The dyeing process of G. caespitosum dye on wool fabrics was optimized using single-factor experiments. Standard fastness tests were conducted to evaluate the sunlight, washing, and rubbing fastness of the dyed fabrics. The color characteristics and color gamut range of the dyed fabrics were evaluated. The obtained colors were compared and assessed with Pantone Matching Systems and Chinese traditional colors. The results showed that phenolic acids and flavonoids were present in the G. caespitosum dye solution as yellow dye compounds. The best dyeing process for wool fabrics was meta-mordanting. The dyed fabrics were bright yellow at 60 °C and golden yellow at 90 °C. All the obtained colors were in the yellow-red range. According to the ISO color fastness standards, wool fabrics dyed with G. caespitosum dye had good color fastness ratings, particularly sunlight fastness. Therefore, G. caespitosum dye is a promising natural yellow dye that can be used for wool fabric dyeing. It has advantages over other known natural yellow dyes and has certain application value.

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Study on Dyeing Properties and Color Characteristics of Wool Fabrics Dyed with Geranium caespitosum L. Extract—A New Natural Yellow Dye

This study reported a sustainable comparative cotton dyeing mechanism of condensed and hydrolyzable tannin enriched extracts by exploiting watermelon rind (WR) and mango seed kernel (MSK) bio-waste. Both crude dye extracts possess various coloring chromophores such as flavonoid, betacyanin, quercetin, β -carotene together with condensed and hydrolyzable tannin at a different level of concentrations, which were confirmed by several phytochemical screenings, thin layer chromatography, and UV spectroscopy. At optimized reaction condition, the resulted fixation rates of various WRCs (at 60  ° C for 60 min) and MSKCs (at 90  ° C for 60 min) were found as 25%–75% and 55%–71%, respectively. MSKCs have higher absorbance intensity and proactive anchoring sites than those of WRCs, resulting in three times higher color strength (K/S). For promoting the dye fixation, cotton fabric samples were chelated with different types of metallic salts (Fe2＋, Al3＋, Sn 2 + , and Cu 2 + ) and 65% and 45% enhanced color strength was found for WRCs (K/S increased from 0.95 to 1.57) and MSKCs (K/S increased from 2.75 to 3.98), respectively. The effects of metal chelation with cellulose chain were estimated in terms of several crystallinity indices, hydrogen bonding configurations, and asymmetric factor and elaborately correlated with the improved dye fixation. In addition, the electrolyte was also added to the dye bath for further improvement of dye exhaustion, thereby granted 12% and 6% higher color depth for WR (K/S increased from 1.57 to 1.76) and MSK dyed fabric (K/S increased from 3.98 to 4.23). Finally, distinguishing colorimetric appearances and excellent colorfastness properties were ensured for different tannin classes.

Md. Luthfar Rahman Liman

Papers

Environmentally benign dyeing mechanism of knitted cotton fabric with condensed and hydrolyzable tannin derivatives enriched bio-waste extracts