EVALUATION OF COCHLOSPERMUM VITIFOLIUM EXTRACTS AS NATURAL DYE IN DIFFERENT NATURAL AND SYNTHETIC TEXTILES

Cochlospermum vitifolium ﬂ owers were evaluated as a raw material of natural dye on different fabrics, natural and synthetic. The dyeing process evaluation was performed by CIELa*b* color coordinates analysis. Color fastness was evaluated using the AATCC 61-1B and AATCC 116 methods. The chemical identifi cation of the compounds in the color fraction was carried out by HPLC–MS/MS. The naringenin was determined to be the color compound. Among the natural textiles, the wool presented the best uniformity of dyeing and fi xation of color, achieving the best hue when a pre-mordant treatment was used. The combination of sodium and potassium tartrate dye resulted in the best fi nal hue, between the yellow and red regions of the CIELa*b* space (L = 49.84, a* = 5.41, b* = 45.52). The dyeing of the wool by the sodium and potassium tartrate pretreatment showed the best fastness properties to the laundering test (ΔE ab = 54.56), as well as in the rub test (ΔE ab = 67.36). The extract of C. vitifolium could be considered as an alternative natural dye for textiles with a protein base (e.g., wool fabrics), obtaining the best results when mordant pretreatment is used.


Introduction
Dyeing is a complex chemical process, involving several physicochemical phenomena, the most important of which is the fi xation (by covalent/hydrogen bond or electrostatic attraction) of the dye to the textile molecules [1,2].
The use of natural dyes is normally limited to a narrow range of hues and exhibits a low-medium color fastness rate [1]. The use of natural dyes by the textile industry has a positive impact on the environment, including lower water and soil pollutions as well as lower toxicity levels on the fl ora and the fauna. At the same time, natural dyes allow for textiles with functional proprieties, such as protection against UV radiation and bacteriostatic/bactericidal properties [3].
The raw materials used to obtain natural dyes can be divided into agricultural/forestry products and residues from the food and beverage industry [21]. Various phenolic compounds (some aromatic phenolic acids, fl avonols, fl avones, and condensed tannins), hydroxy indoles, carminic acid, carotenoids, curcuminarin, and some quinones (tectoquinones and dimeric quinones) have been identifi ed as the responsible of the fi nal hue of dyes extracted from vegetables, plant tissues, and/or fruits [22].
Several phenolic compounds (phenolic acids, fl avones, and fl avonoids) have been identifi ed as responsible for color in various natural dyes and are used to obtain yellow and orange hues [2].
Cochlospermum vitifolium is widely distributed in tropical and subtropical regions of Mexico and Central America [23]. In Mexico, it is known as wild cotton, yellow rosewood, or marshmallow fl ower [24]. The pharmacological proprieties of the C. vitifolium bark have been documented, but there is a limited reference to the use of bark and stems as a dye for cotton-based textiles that has been documented [25]. There is no available information about the use of the fl oral tissue as a source of natural dye, although there are some reports of its use as a food dye in southern Mexico. Some phytosterols and phenolic compounds have been elucidated from C. vitifolium fl ower extract, including the fl avanone family of compounds, which are the compounds of the highest concentration [26,27].
The objective of this work is to evaluate the effectiveness of the colorful fraction extracted from fl owers of C. vitifolium as a dye on natural and synthetic textiles.

Plant material
Fresh fl owers of C. vitifolium were collected in the rainforest zone of Oaxaca, Mexico. The fl oral material was subjected to a drying process at 50°C for 24 h, and then, the sepals and the pedicles were removed from the fl oral structure.

Extraction process
The extraction of the dye was carried out in the following two phases: (i) Water (80°C) was added to the dried material in a ratio of 1:5 (w/v). The material was macerated for 24 h at 25°C. The solid material was removed by fi ltration. (ii) The fi ltered solid material was macerated again in a water/ethanol solution (20:80, v/v) for 24 h at 25°C. The solid material was removed by fi ltration. Both extracts were combined, and then, they were subsequently evaporated under a nitrogen stream (25°C).

Pretreatment
The fabric samples were pretreated with inorganic (sodium and potassium tartrate, copper sulfate, and potassium sulfate) and organic (tannic acid) mordants. The liquor-to-goods (L/G) ratio was 50:1. The process was carried out at 80°C for 30 min and stirred at 150 rpm; then, the textile matrices were rinsed with distilled water at room temperature (25°C) to remove the nonadsorbed mordant.

Dyeing of textile materials
The fabric samples were dyed at an L/G ratio of 20:1. The amount of the dye (%owf) was 12.5%; the dye was dissolved in 1 l of deionized water. The dyeing process was carried out at 80°C for 60 min and stirred at 150 rpm. The excess nonadsorbed dyeing solution was removed by rinsing the fabric samples with distilled water at room temperature (25°C). The textiles were dried at 25°C.

Textile color measurement
The measurement was carried out by comparing the hue of the fabric samples before and after the dyeing process. To evaluate the effect of the dyeing process, the CIELa * b * scale was used; the hue differences were determined by the following Eq. (1): where DE ab is the total color difference between nondyed and dyed textiles, DL is the luminance difference between nondyed and dyed textiles, Da is the red hue difference between nondyed and dyed textiles, and Db is the blue hue difference between nondyed and dyed textiles.

Fixation ratio
The fi xation value of the dye absorbed was determined spectrophotometrically according to the methodology of Lewis and Vo [28]. The dye absorption was evaluated at 248 nm (wave width of maximum absorption). The fi xation ratio was determined by the following Eq. (2): where F is the fi xation ratio, A 0 is the absorbance of the dyeing liquor at the beginning of the dyeing process, A 1 is the absorbance of the dyeing liquor after the dyeing process, and A 2 is the absorbance of the wash-off solutions after the dyeing process.

Kinetics of the dyeing process
The reaction rate constant (k) was evaluated by analyzing the reaction order of the dyeing process. The standard affi nity of the dye (-Dλ) was evaluated according to Eq. (3), based on the assumption that the processes of dyeing by natural products are characterized by dispersion-adsorption mechanisms similar to those exhibited by the dispersed dyes [29]: where -μ is the standard affi nity (kJ mol -1 ), C 1 is the concentration of the dye in the liquor after dyeing process (mol l -1 ), C 0 is the concentration of the dye in the liquor before dyeing process (mol l -1 ), R is the constant of the ideal gases (8.314 J mol -1 K -1 ), and T is the temperature (K).

Color fastness to laundering of textiles
The color fastness was carried out using a launderometer. AATCC 61-1B * -modifi ed methodology was used [30]. The modifi cations consisted of the use of a solution of TritonX-100 of a concentration of 72.9 mg ml -1 as an anionic detergent; no powder detergent was added. The effect of the washing process was quantifi ed by the difference of the color between the fabric samples before and after the washing process, according to Eq. (1).

Color fastness to crocking
The color fastness was carried out using a crockmeter. The AATCC 116 methodology was used [31]. The rubbing effect was quantifi ed by the difference between the fabric sample before and after the washing process, according to Eq. (1).
The fractions of interest were evaluated using liquid chromatography-positive ion-ESI-MS using a C 18 column (150 mm x 2.0 mm, 3 μm; Variant, USA). The chromatographic methodology used was as follows: from 1 to 20 min, a mobile phase was composed of water:methanol:acetic acid (79.2:19.8:1; v/v); at 20-30 min, the methanol concentration was decreased until it reached the composition of methanol:acetic acid:water (49.5:1:49.5; v/v). At the positive ion mode, the needle potential was 4.5 kV, the tube lens offset was -80 V, and the heated capillary temperature was 270°C. The scan mass spectra were collected in the full scan positive mode (50-700 m/z).
The color phase compounds were identifi ed and analyzed their mass fragmentograms and by direct comparisons of the structural information reported for C. vitifolium fl ower tissues [26,27].

Statistical analysis
ANOVA was used; the fabric sample and the type of mordant were factors. The CIELa * b * coordinates, the fi xation ratio of the dye, and the color fastness were evaluated as response variables. The statistical analysis was carried out using the Statistica ver.7 software.

Dyeing process
The dye solution from C. vitifolium fl ower tissues produced hues from yellow, under basic conditions, to dark orange, under acid conditions (Figure 1). There was no affi nity between the synthetic surfaces (acetate and polyester fabric samples) and the dye extract aqueous solution.
The affi nity of the dye extract for the cotton fabric sample was poor, with incomplete dyeing in extension and fi nal steps ( Figure 2).
For the wool fabric sample, uniform dyeing was obtained ( Figure 3). Due to the nondyeing results in synthetic samples, the evaluations of the dyeing process and fastness probes were only carried out on the wool fabric sample.
The affi nity between the textile material and the dye depends on several factors, such as affi nity through the formation of covalent bonds, hydrogen bonding, and hydrophobic interactions [15], e.g., in cellulose-based fabric samples, when immersed in polar solutions, the cellulose takes an electronegative character that prevents their dye by anionic   AUTEX Research Journal, DOI 10.2478/aut-2019-0056 © AUTEX http://www.autexrj.com/ reactive dyes. The protein-based fabric samples, such as wool and silk, retain the dyes by hydrogen bonds [32].
The use of sodium and potassium tartrate or tannic acid as a pretreatment generated dye textiles with higher luminosity and hues in the yellow region ( Table 1). The copper sulfate and potassium sulfate mordants' pretreatment generated more opaque and hues located near the red region.
The overall effect of the dyeing process (hue) was significantly influenced (p < 0.05) by the type of mordant. The tartrate of sodium and potassium salt mordants resulted in better hues (DE ab = 67.71).

Dye fixation efficiency
The fixation efficiency values ( Table 2) show that the potassium sulfate generated the best dye fixation ratio (70.4%), while the sodium and potassium tartrate generated the lowest dyeing fixation.

Dye fastness
The evaluation of the wool dyed to the rub test (Table 3) indicates that the highest color fastness was observed in the textile pretreated with sodium and potassium tartrate (DE ab = 67.36), while the pretreatment with cooper sulfate resulted in the higher loss of dye (DE ab = 45.64).
The results of the evaluation of the dyed wool laundering fastness test (Table 4) indicate that the lower color proprieties were from wool pretreated with cooper sulfate (DE ab = 36.73), while the pretreatment with sodium and potassium tartrate salt resulted in the lower loss of dye (DE ab = 54.56).
Color fastness and dye fixation are not concepts that describe the same properties. Dye fixation refers to a physicochemical process that depends on the nature of the active sites of the fabric surface molecules, the dye molecule chemical characteristics (a type of functional groups) and physical characteristics (steric hindrances), and the solvation medium used for the dye dispersion (solvent). These characteristics determine the dye absorption, diffusion, and fixation from the solvent to the fabric fibers and the nature of the bonds formed between the dye molecules and the fabric surfaces [33]. Different superscripts indicate significant differences (p < 0.05) between treatments. The potassium sulfate has a higher affinity between the textile and the dye (9.69 kJ mol -1 ). The evaluation of the color fastness is one of the most important textile fabric properties. It is a property derived from the dye and the fabric fiber bonds. The fastness refers to the degradation of the fabric color/hue characteristics, under specific conditions, such as exposure to light, water, detergents, or to a specific fabric use condition. The color fastness characteristics determine if the fabric is suitable for the intended purpose. It is an identifying characteristic of the dyeing process. If color fastness is good, then fabric quality is high. Therefore, color fastness is one of the most important quality factors for the buyer to justify choosing a particular dyed fabric.

CONCLUSIONS
The dye extracted from C. vitifolium flower was not able to dye cellulose acetate or polyacrylonitrile fabric samples.
It is possible to dye wool fabric samples with C. vitifolium flower extract, using metallic and phenolic mordants to obtain dark orange hues.
Sodium and potassium tartrate salt pretreatment improved the higher color fastness characteristics according to the rub and laundering tests.
The naringenin was identified as the main coloring compound in the flower extracts.