Assessment of Colorimetric and Fastness Properties of Prangos Ferulacea (Jashir) Dyed Wool Yarns in Conjunction with Mixed Metal Mordant Combinations via Reflectance Spectroscopy

ABSTRACT Prangos ferulacea (Jashir) plant possesses various phytoconstituents such as coumarins, flavonoids, alkaloids, umbelliferon, and monoterpenes and has been used in traditional medicine. The presence of flavonoids in aerial parts of Prangos ferulacea necessities further examination of using them as a source of natural colorants for developing natural and beautiful shades on wool yarns. This will add one more new effective natural dye source and ease the dependency of the present-day textile industry on synthetic colorants. Simple adsorption of aqueous dye extract on the wool followed by evaluation of buildup properties using 28 different binary metal combinations as mordants were studied in this study. The dyeing was performed by exhaust dyeing method and dyed samples were analyzed through reflectance spectroscopy and analyzed in terms of color strength, CIEL*a*b*, and CIEL*c*ho values. Color characteristics were evaluated on a spectrophotometer under D65 illuminant and 10° standard observer. FT-IR and SEM analyses were performed to characterize P. ferulacea dyed wool yarns. The results showed that overall 29 different shades having very good to excellent fastness properties were produced by the use of different metallic salt combinations in natural dyeing of wool yarns using aerial parts of P. ferulacea as a source of natural dye.


Introduction
Natural products that are not just "eco-friendly" and "organic" but also synthesized or produced "ethically" became more and more common among consumers in the present era of scientific and research developments. The present research is being focused on the strategies to substitute petrochemical products by plant-derived natural materials Rather, Shahid-Ul-Islam, and Mohammad 2015;Zhang, Shahid-Ul-Islam Rather, and Li 2022). Natural dyes and pigments have made a comeback in the textile dyeing sector as a valuable alternative to most of the synthetic dyes, which are thought to be harmful to humans (Carcinogenic) and aquatic ecosystems (Ahlström, Eskilsson, and Björklund 2005;Javadian, Angaji, and Naushad 2014;Rather, Haji, and Shabbir 2021). Biodegradable, sustainable, and environmental-friendly natural colorants derived from renewable resources like plants and insects are gaining popularity in the dyeing industrial sectors (Zhang et al. 2021;Zhou et al. 2022). A variety of chemical compounds present in dye-yielding plants including tannins, anthraquinones, alkaloids, naphthoquinones, flavonoids, and carotenoids are being studied for their potential usage to produce colorful textiles of different hues and tones (Koh and Hong 2014;Sadeghi-Kiakhani et al. 2021). Because of the inherent biological properties of dye components (tannins, flavonoids, anthraquinones, naphthoquinones, and carotenoids), researchers have employed them for the production of functional textile materials with insect repellent, antimicrobial, antioxidant, UV protection, and fluorescent properties (Rastogi, Jain, and Negi 2022;Rather et al. 2019;Safapour, Sadeghi-Kiakhani, and Eshaghloo-Galugahi 2018;Zhou et al. 2020Zhou et al. , 2022. More recently, researchers are exploring the use of waste by-products of plant origin to reduce the cost of natural dyeing processes in addition to the introduction of new dye sources (Amutha et al. 2022;Zhang et al. 2021;Zhou et al. 2022).
Natural dyeing is a centuries-old tradition in Iran, where textile items such as fibers, yarns, and other clothing's are soaked in a precise combination of pigments, resulting in the production of beautiful colors. In Achaemenid-era (c. 550-330 BC) famed Pazyryk rug was recovered from the Bolshoy Ulagan dry valley of the Altai Mountains in Kazakhstan in 1949 which bears natural yellow, red, blue, and green colors providing a clue of the long history of natural dye processes in this area . The development of carpet dyeing was witnessed in the Safavid era (1501 -1736) with crimson red, blue, green, pale yellow, and orange colors which are similar to the present-day pigments. The dyers also practiced the mixing of two or more colors, providing hues that are different from each other. Mixing violet and red created bright magenta and further addition of yellow pigment turns it into persimmon orange (Aali et al. 2012;Pollard et al. 2008). Prangos ferulacea (L.) Lindl. plant (Jashir) from the order Umbellales, the family of Umbelliferae (Apiaceae) and subfamily of Smyrneae grows wildly in different parts of eastern and western Iran. P. ferulacea is used as animal fodder and for yogurt seasoning (Bruno et al. 2021;Sadraei et al. 2013). In Turkey (eastern cities), P. ferulacea is used to provide a characteristic aroma with antimicrobial properties to Otlu cheese. In Persia, P. ferulacea has been explored for use in flok medicine as an antimicrobial, tonic for gastrointestinal and liver disorders, anti-inflammatory, anti-viral, and anti-helminthic agent. It also contains emollient, antiflatulent, and sedative properties (Kafash-Farkhad, Asadi-Samani, and Rafieian-Kopaei 2013). Moreover, it has been reported that P. ferulacea is a rich source of different antioxidants (Delnavazi et al. 2017). The protective effects of P. ferulacea are directly related to the presence of phenolic compounds (Coruh, Celep, and Özgökçe 2007;Mavi et al. 2004). The different classes of compounds found in different parts of P. ferulacea are coumarin, flavonoids, terpenoids, phytosterols, and other miscellaneous compounds. From the aerial parts of P. ferulacea, quercetin and isorhamnetin have been isolated and characterized by 1 H-NMR, 13 C-NMR, EI-MS, and UV spectral analysis (Delnavazi et al. 2017;Mottaghipisheh et al. 2020) (Figure 1). Reverse phase HPLC of P. ferulacea aerial parts extract revealed that active dyeing components present are 3-O-glucuronides of quercetin and isorhamnetin, or rutin . The nature of the sugar moiety P. ferulacea flavonol glycosides was determined by acid hydrolysis and the products were analyzed by LC-MS (Bigge et al. 1995). Further, it was found that the flavonol glycosides in P. ferulacea are identical to those found in Anethum graveolens L. which had previously been identified as quercetin 3-O-β-D-glucuronide and isorhamnetin 3-O-β-D-glucuronide (Teuber and Herrmann 1978). Additionally, β-pinene (43.1%), α-pinene (22.1%), and δ-3-carene (16.9%) were the main components of the essential oil component of the aerial parts of this plant (Bruno et al. 2021;Delnavazi et al. 2017).
The results of a recent study ) have shown that the dried plant parts of Prangos species can be directly used for dyeing processes as the dried parts are devoid of any free aglycones. Flavonoid-based natural dyeing of wool fibers presents a novel and cleaner production technology for combating antibiotic resistance with the successful production of the antimicrobial and antioxidant wool substrate (Zhou et al. 2022). In light of the conclusion drawn by ) and Zhou et al. (Zhou et al. 2022), P. ferulacea can be used as a source of natural yellow dye for the production of yellow-colored wool yarns. It was recently discovered that P. ferulacea can be used to dye wool fibers and the optimization of dyeing parameters was done using the response surface methodology approach (Barani and Rahimpour 2014). However, we herein report for the first time the pre-mordanting of wool with P. ferulacea dye in conjunction with binary metal salt combinations to develop shades of acceptable colorimetric and fastness properties with specific hues and tones. The results have been discussed well in terms of the possible relationship between dye structure, the coordination ability of metal ions, and metal-wool-dye interactions.

Materials and chemicals
Commercial scoured 100% wool yarn (20/4 Nm), used as pile yarn for handmade carpet production, was used in this study. Aerial parts of P. ferulacea plant were used as a source of natural dye, purchased from the local market in Yazd, Iran. Nonionic detergent (Nikogen SDN) was used for the scouring of wool. Distilled water was used for the preparation of solutions, mordanting, and dyeing.

Dyeing with and without mordants
Before mordanting and dyeing, wool yarns were scoured in a solution of 5 g/L Nikogen SDN (nonionic detergent) at 60°C for 30 min with a liquor ratio of 40:1. The air-dried wool yarns were then premordanted using twenty-eight different binary metal mordant combinations with a liquor ratio of 50:1 at 95°C for 60 min . Mordanted samples were thoroughly rinsed with running tap water several times to remove surplus (unused) mordants and dried under shade. The details of the binary mixed metal mordant combinations with respective concentrations are provided in Supplementary data (Table S1). Dyeing experiments were performed with a liquor ratio of 40:1 for 75% (o.w.f.) P. ferulacea aerial parts extract under the acid condition of pH 5 (adjusted by acetic acid) at simmering point (93ºC) for 60 min . Finally, the dyed samples were removed from the dyeing solution and washed thoroughly under running tap water. The samples were dried in shade and stored for the fastness rating assessments.

Color parameter assay
The colorimetric characteristics (L*, a*, b*, c*, h o , and K/S) of wool yarn dyed with 75% (o.w.f.) P. ferulacea natural dye were recorded with a reflectance color-eye XTH spectrometer, X-Rite Inc. in the range of 360-750 nm under the D65 illuminant and 10° standard observer. The color coordinate L* corresponds to the brightness index (100 = white; 0 = black), a* corresponds to the red-green coordinate of color space diagram (+ive = red; -ive = green), b* corresponds to the yellow-blue coordinate (+ive = yellow; -ive = blue), c* gives the color purity or vividness -dullness ratio (100 = vivid; 0 = dull) and h 0 corresponds to the hue angle (Shahid-Ul-Islam Rather et al. 2017). The color strength (K/S) is related to the adsorption of the dye onto the wool surface and gives the depth of the shade . The data of color parameters are the average of 4 individual measurements.

Colorfastness assay
Wash fastness measurements of all dyed wool yarns were tested as per the ISO 105-C10:2006(E) standard. The samples were washed for a period of 30 min at 60°C and were evaluated for color change and degree of staining on adjacent cotton and wool fabric on gray scale. Rub fastness tests were performed as per ISO 105-X12:1993 (E) standard. The Lightfastness test was done as per ISO 105 B02:1988 (E) standard using a xenon arc lamp and samples were analyzed with a blue scale.

FT-IR spectral analysis of dyed wool yarns
FT-IR spectra of the powdered native, Al/Fe mordanted , and Al/Fe mordanted dyed wool yarn samples was recorded using a Jasco 680-plus FT-IR spectrometer with 4 cm −1 resolution between 4000-500 cm −1 (Rather, Shahid-Ul-Islam, and Mohammad 2015).

Surface morphology of dyed wool yarns
Surface morphology of native, Al/Fe mordanted , and Al/Fe mordanted dyed wool yarns was observed using TESCAN MIRA3 FEG Scanning Electron Microscope at 10 kV accelerating voltage. Samples were glued to aluminum stubs with colloidal silver paint for conductivity and sputter coated with gold for 3 min in an argon atmosphere . Figure 2 shows the variation of color strength (K/S) dyed wool yarns mordanted with the binary mixed metal combinations. Thus, by varying the combination of metal mordants in conjunction with 75.0% (o.w.f.) P. ferulacea aerial parts extract, we can achieve a range of colors with varying hues and tones. From the results, it is observed that wool yarns dyed P. ferulacea dye extract exhibit significant variations in K/S values due to different mordant combinations. Out of all binary metal combinations, the highest K/S values were observed with Al/Cu, Al/Sn, Fe/Sn, Sn/Co, Sn/Ni, and Sn/Zn with values of 24.78, 24.39, 25.05, 24.65, 24.13, and 26.78 respectively (Supplementary data; Tables S1-S5). This is because metal mordants form chelate complexes with the phenolic group's of dye molecules and functional groups (amino and carbonyl) of wool fiber (Malacaria et al. 2022;Uddin 2015) (Figure 3). Such coordination bonding enhances the interaction between dye molecules and textile substrate, subsequently resulting in higher color depth (higher K/S values) (Ayele et al. 2020). In a particular binary metal combination, the retaining effect (bright hues) of a particular metal (e.g. Sn  mordant in various Sn combinations) is due to the higher coordination ability (more charge to size ratio) of Sn compared to Al, Fe, Co, Ni and Zn metal ions which is evident from the higher K/S values of corresponding combinations (Rather et al. 2018;Rather, Shahid-Ul-Islam, and Mohammad 2015). From the photographs of dyed wool yarns (Supplementary data; Figures S1-S5), it is evident that most of the Sn combinations (Sn/Al, Sn/Fe, Sn/Co, Sn/Ni, and Sn/Zn) mordanted wool yarns have retained their characteristic bright hues . While in Sn/Cu and Sn/Cr combinations, more contributions come from Cr and Cu compared to Sn. It is clear that varying the amounts and the nature of mordants in a particular combination with constant amount of dye, helps to develop a range of yellow colored shades on wool yarns with different hues and tones.

Lightness (L*), chroma (c*), and Hue angle (h o )
From the colorimetric values (CIEL*a*b* and CIEL*c*h o ) presented in Tables S1-S5 for various binary mixed metal mordanted wool yarns, it is clear that application of P. ferulacea dye extract produced shades of high lightness (L*) and low color saturation (c*) with hue angle ranging between 82° to 92° ( Figure 4). Among all binary mixed metal combinations, the copper series (Cu/Sn, Cu/Co, Cu/Ni, Cu/ Cr, Cu/Zn) showed lower lightness (L*) values compared to the aluminum, iron, and tin series. a* -b* color coordinates Figure 5 displays the plotted a*-b* graphs of P. ferulacea dyed wool yarns mordanted with different binary metal mordants. As depicted from the a*-b* graph, the data plotted for most of the developed shades for binary mixed mordanted wool yarns lie in the red-yellow zone of the color space diagram. Exceptionally, the a*-b* plots of Al/Fe, Al/Sn, Al/Co, Fe/Zn, Sn/Cr, and Sn/Zn lie in the green-yellow coordinate of the color space diagram with dominant yellow color. The mordanted samples show significant variations in the color of dyeing imparted to wool yarns by the use of different metal combinations. Dyeing with all mordant combinations resulted in color shades with low a* and high b* values, indicating less reddish and more yellowish tincture except Fe/Cr combination which is shifted more toward the red region of the yellow-red coordinate with a* value of 6.28. Darker shades were provided by the iron and copper combination series which possessed comparatively lower b* values and provided the greatest change in color appearance with a shift from yellow to yellowish-brown color. In general, a*-b* values were in good agreement with the visual assessment.

Fastness properties
Light, wash and rub fastness properties of the fastness of P. ferulacea dyed wool yarns were evaluated as per the respective ISO standards. Table 1 shows the fastness characteristics of control dyed and mordanted dyed samples. Control dyed samples possess a lightfastness rating of 4 (good lightfastness) and a color change rating of 4 (Very good). Application of binary mixed metal mordant combinations has increased the fastness properties concerning the nature and strength of interactions between wool, metal, and dye molecules ). Among different mordant series, it was found that tin combinations possess low color change fastness properties with a rating of 4 and lightfastness ratings of 5-6. No or least staining was observed on adjacent cotton and wool fabrics with ratings in the range of 4-5. Similarly, the results for rub fastness for all the shades were assessed using grayscale and in all the cases, dry rub fastness ratings were better than wet rub fastness properties with ratings between 4 and 5.

FT-IR spectral analysis of dyed wool yarns
The infrared spectra of native wool yarns indicate the characteristic absorption bands assigned to the peptide bond which is the fundamental structural unit of the polypeptide chain. The different atoms of the peptide bond (IR active) oscillate/vibrate; giving rise to three different IR spectral bands designated as amide I, II, and III bands (Wojciechowska, Włochowicz, and Wesełucha-Birczyńska 1999). The amide-I represents the C=O vibrations and falls in the range of 1690-1600 cm −1 . Amide-II band is linked with the deformation of N-H and stretching vibration of -C-N bond and it appears in the range of 1580-1480 cm −1 . Likewise, amide-III band is linked with the vibrations of C-H and C-N which appears in the region of 1350-1220 cm −1 (Khan et al. 2012). The position of amide bands is attributed to the changes in the conformation of keratin molecule. The IR spectrum of native wool yarns has its own characteristic vibrational bands/FT-IR spectral bands: a high intensity and sharp band at 3380 cm −1 representing N-H and O-H stretching frequency. Sharp band at 2964 cm −1 represents symmetric stretching of methylene group (-CH 2 ) (Rather, Shahid-Ul-Islam, and Mohammad 2015). Two more bands at 2920 and 2853 cm −1 represents asymmetric methylene stretching frequencies. Strong peaks at 1635 cm −1 represents amide-I (-C=O) stretching band. Sharp absorption peak around 1536 cm −1 is linked to the secondary amide, N-H bending, and C-N wagging vibrations (Ricci et al. 2015). 1226 cm −1 peak represents the virbations linked with amide-III band of peptide bond. Peak at 1076 cm −1 belongs to the S=O vibrations of cysteic monoxide group of polypeptide chain of wool fiber (Belukhina, Milasiene, and Ivanauskas 2021;McGregor, Liu, and Wang 2018). The wave number shift and intensities of respective bands were found to be affected significantly by mordanting with Al/Fe mordanting  (Figure 6), which have been briefly summarized in Table 2.

Surface morphology of dyed wool yarns
The surface morphological features of native, mordanted (Al/Fe), and mordanted dyed wool yarns are shown in Figure 7. SEM images of native wool yarns show normal surface morphology (Figure 7a). It can be clearly seen that mordanting with Al/Fe mordant combinations and subsequent dyeing processes does not alter surface morphology of wool yarns. However, the surface of mordanted sample reveals coarser surfaces due to deposition of well dispersed metal particles with no or little aggregation (Figure 7b). Figure 7c shows that mordanted wool yarns dyed with 75% (o.w.f.) P. ferulacea aerial parts extract showed deposition of dye molecules on its surface. The surface of mordanted dyed yarn sample showed darkening effect due to the  deposition of more dye molecules which clearly indicates role of metal ions in increasing color depth (coating) of dyed wool yarn .

Conclusion
The present research was initiated for the development of colored wool yarns with 75.0% (o.w.f.) P. ferulacea aerial parts extract in conjunction with different binary mixed metal salt combinations. The research examinations asserted the use of P. ferulacea natural dye for the development of yellowcolored wool yarns with industrially acceptable colorimetric (CIEL*a*b* and CIEL*c*h o ) and fastness (light, wash, and rub) characteristics. The maximum improvement in the dye uptake (K/S) value of 26.78 was recorded with 1.5% (o.w.f.) of stannous chloride +2.5% (o.w.f.) of zinc sulfate combination for 75.0% dye concentration. Each metallic salt-mordant combination produced deep yellow to yellowish-brown shades with significant differences in the hue of the color. The higher values of color depth (K/S) of mordanted samples compared to the control dyed samples were due to the coordination complex-forming ability of metal ions with dye molecules within the fiber structure. The increase in the adsorption of dye molecules and surface characteristics after mordanting and dyeing procedures were verified by FT-IR spectral analysis and SEM images. The surface morphology showed no damage to the cuticle surface of wool yarns under high temperature (93 °C) dyeing. Therefore it can be concluded that different binary metal salt combinations can be successfully utilized for producing beautiful natural yellow shades on wool yarns with P. ferulacea aerial parts extract.

Disclosure statement
No potential conflict of interest was reported by the author(s).