Valorization of bio-colorants extracted from Hypercium scabrum L. plant for sustainable and ecological coloration of wool yarns.

Recently, natural dyes are being explored all over the world as safer and highly sustainable bio-based alternatives to synthetic dyes. Agricultural wastes and plant by-products are the most commonly explored alternatives with dual benefits of waste reclamation and sustainable dye production with extra value-adds. Hypercium scabrum plant contains interesting bio-dye molecules with high flavonoids and tannin contents. The present study aims at exploring the potential of H. scabrum plant extract to color wool textiles with a focus on sustainable bio-dye production and fastness properties. The extracted bio-dye was quantitatively (for total phenolic (2.733 mg per CE/g) and total flavonoid (1.140 mg per GAE/g) content using the Folin-Ciocalteu method) and qualitatively (UV-Vis, FT-IR, and EDX) characterized. The effect of dyeing parameters like pH (2-8), temperature (60-90 °C), dry-weight content of plant material as a dye (25-150% o.w.f.), and dyeing time (15-120 min) on color strength (K/S) values were assessed. Color fastness assays showed good resistance to light, washing, and rubbing. The effect of artificial aging (Xenon arc lamp) on the color strength of dyed wool yarns under different exposure times (0-48 h) was explored. The highest color fading occurred in control dyed samples with a first-order rate constant of 131.57 h-1 and a half-life period of 5.26 x 10-3 h. Color difference (ΔE) values suggested that mordanted samples showed less fading compared to control dyed samples at equal times of Xenon exposure. Additionally, the dyed samples were washed in double distilled water, tap water, and 4 g/L NaCl solution to check their effects on the corresponding K/S values while 4 g/L NaCl solution mimics the real conditions of perspiration. Maximum color leaching occurred in 4 g/L NaCl washing with a first-order rate constant of 11.57 min-1. Cost analysis of the dye extraction and dyeing procedure revealed that the process is sustainable and economical. Thus, the use of H. scabrum whole plant can provide a clean, economical, and sustainable source of alternative natural dyes that can be used to substitute synthetic analogs.

Grafting of chitosan-acrylamide hybrid on the wool: Characterization, reactive dyeing, antioxidant and antibacterial studies.

This study presents a new approach to enhance reactive dye uptake and functional finishing of wool yarns via simple grafting with synthesized chitosan-acrylamide (Ch-Ac) hybrid. To this, Ch-Ac was synthesized and characterized with fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Then, Ch-Ac was grafted on wool, characterized with FTIR, SEM, and weight gain analysis and dyeability with two commercial reactive dyes. Results showed that Ch-Ac treated wool could be dyed at lower temperatures (ca. 40 °C), times (ca. 30 min), and amount of reactive dye (2% owf) as compared to raw wool. Also, deeper shades not obtainable in conventional dyeing could be attained using Ch-Ac treated wool. In addition, Ch-Ac treatment imparted very good radical scavenging and excellent antibacterial activity against gram-negative (E. coli) and gram-positive (S. aureus) bacteria. Color fastness results confirmed that Ch-Ac treatment had no adverse effect on durability of dyes against washing, light, rubbing and perspiration. The results of this study clearly indicated that Ch-Ac can be used in eco-friendly functional finishing of wool with enhanced reactive dye uptake, minimized residual dye in wastewater, saving in consumption of chemicals, energy, and time of dyeing.

Functionalization of poly(amidoamine) dendrimer-based nano-architectures using a naphthalimide derivative and their fluorescent, dyeing and antimicrobial properties on wool fibers.

Novel naphthalimide-poly(amidoamine) dendrimer fluorescent dyes were synthesized, and their structures were identified and confirmed using different characterization methods such as Fourier transform infrared, (1) H NMR, (13) C NMR, differential scanning calorimetry, elemental analysis and UV-vis spectroscopy. The spectrophotometric studies demonstrated absorption maxima (λmax ) and extinction coefficient (εmax ) values in the ranges of 429-438 nm and 25,635-88,618 L/mol/cm, respectively. The dyeing, fastness and antimicrobial properties of dyed wool fibers were examined. Colorimetric measurements demonstrated a greenish-yellow hue with remarkable fluorescence intensity on dyed wool. Although the fastness properties of naphthalimide dye on wool fibers were poor/moderate, color fastness was appreciably improved through modification of the dye using dendrimers. The results revealed that the newly synthesized dyes are potent antimicrobial agents on wool fibers. Overall, it was deduced that poly(amidoamine) (PAMAM) dendrimers could be exploited as a promising tool in tailoring the different properties of naphthalimide dyes, being suitable for dyeing and antimicrobial finishing agents for wool fibers. Copyright © 2015 John Wiley & Sons, Ltd.