Optimization of Marigold Flower Dye Using Banana Peel as a Biomordant

ABSTRACT This research aims to optimize the dyeing process of marigold flower dye by using banana peel extraction as a biomordant in cotton fabrics. In the beginning, we investigated the optimal condition for extracting tannin compounds from fresh banana peel. Then, the woven cotton fabrics were dyed with marigold flower extraction at 90°C for 60 min with three different mordanting methods; pre-mordanting, post-mordanting, and meta-mordanting. With meta-mordanting, the ratios of mordant to dye solution were varied. The mordanting temperature and time of each methods were studied. The color strength, CIEL*a*b*, wash fastness, and light fastness were also inspected. It was found that the optimal condition for tannin extraction from the fresh banana peel was at 90°C, 1 h. When dyeing cotton fabrics with marigold flower dye by the pre-mordanting and post-mordanting method, the optimal mordanting condition was achieved at 60°C, 120 min, as the dyed fabrics showed the highest color strength. Moreover, the optimal condition of meta-mordant method was shown at 30°C, 90 min at the mordant to dye = 2:1 and 30°C, 60 min at the mordant to dye = 1:1 and 1:2. The color fastness of the mordanted cotton fabric was improved, especially the post-mordant method.


Introduction
In recent years, the natural-dyed fabric has gained more interest and acceptance as the natural dyeing process is environmentally and does not cause negative effects (Arifeen et al. 2021;Lambrecht et al. 2020). The natural color normally comes from a sustainable source such as plants, animals, or minerals. The bio-waste and by-products sources from various industries and agriculture were also the alternative natural dye source. However, cotton could not attach to dye molecules properly because of cotton's chemical structure, which lacks amino and carboxyl groups. Therefore, mordant was introduced into the natural dye dyeing process to fix the dyestuff in or on the textile material (İşmal and Yıldırım 2019). Biomordant, which mostly came from vegetal sources, were used regarding their properties, such as aluminum-hyperaccumulating plants were used as substitute for alum mordant, copper-rich plants were used as substitute for copper mordant and some plants were a rich source of tannin (Shahid, Salam, and Mohammad 2013). Tannin is a polyphenolic compound that has a high molecular weight. Using tannins substance in cotton dyeing could retain coloring matter permanently because of the covalent bonds formed by the interaction of any quinine or semi-quinone groups in the tannins and could bond with cellulose fiber tannin any other suitable reactive group (Prabhu and Bhute 2012;Prabhu and Teli 2014).
Banana (Musa sapientum L.) originated in Southeast Asia and is widely planted in every part of Thailand. The banana fruit contains high nutrition and can be processed into various types of food. After that, there were loads of banana peel waste after the food processing. It was reported that banana peel contained tannin (El Barnossi, Moussaid, and Housseini 2021) which can be used as the natural mordant in the natural dyeing process. It was found in the previous study that banana peels were used in the textile dyeing process; for example, the extraction from Musa, cv. Cavendish was dyed on cotton fabric using iron as the mordant, and the resulted fabrics resisted UV radiation and E. coli, S. aureus, and K. pneumonia (Aboul-Enein et al. 2016;Babu 2017). The other parts of the banana tree, such as banana sap, might dye cotton fabric using alum, iron, copper, and tin as the mordants .
Marigolds flowers (Tagetes erecta L.) are yellow to orange-red. They are used for decoration and worship in religious ceremonies (Teli and Ambre 2017). Their petals are a rich source of carotenoids and lutein. Marigold flowers contain lutein as a natural carotenoid dye, flavonoids, and vitamin C (Jothi 2008). Previously, research showed the utilization of marigolds flower extraction as the natural dye in the textile dyeing process with different chemical mordants such as copper, alum, sodium chloride, citric acid. Additionally, the pre-treatment of the fabric using Cs-137 gamma irradiator was studied to improve the color strength and color fastness (Adeel et al. 2017).
This research aimed to extract tannin from the banana peel waste and its application as a natural mordant for dyeing cotton fabrics with marigold dye extraction. The total phenolic content of the fresh banana peel extraction was also investigated. In this research, there were three different mordanting methods; pre-mordanting, post-mordanting, and meta-mordanting. The optimal mordanting parameters, including temperature and time, were explored during the mordant process. The ratio of mordant to dye in the meta-mordanting method was also varied. The color strength, color coordinates were used to evaluate the optimal condition for cotton fabrics with and without natural mordanting. The wash fastness and light fastness of the dyed cotton fabric were also tested.

Materials
Desized and scoured plain weave 100% cotton fabric with 103 g per square meter (120 end per inch and 54 pick per inch) was used in this research. In addition, fresh banana and the fresh marigold flower were purchased from a local market.

Extraction of banana peel
Tannin from banana peel was extracted with water as a solvent because this technique is simple and its lower cost (Das et al. 2020). 100 g of fresh green-ripe banana peel was cut into small pieces and extracted in 300 mL of water at 30, 60, and 90°C for 30, 60, and 90 min. After the extraction, the mixture was cooled down and filtered. The banana peel extraction obtained at different conditions were used for evaluating the total phenolic content. Later, the extraction which gave the maximum tannin content was used to optimize the mordanting parameters in the dyeing process.

The total tannin content in the banana peel extraction
We examined the banana peels for the amount of tannins. The analysis method was based on the previous study with few modifications (Muangrat, Tomtong, and Luangpan 2016). First, 250 mL of the sample extract was transferred into a 5 ml volumetric flask containing 2.5 mL of distilled water. Then, 250 μL of Folin-Ciocalteu reagent and 2 mL of sodium carbonate solution were mixed. After incubation for 40 min at room temperature, the absorbance at 765 nm was measured by the UV/VIS Spectrometer. The estimate of the tannin content was carried out in triplicate. The tannin concentration was calculated using the tannin acid standard curve based on the reaction of Folin-Ciocalteu reagent with a known concentration of tannic acid.

Preparation of marigold flower dye
The fresh marigold flower's petals were separated and extracted in the water at L:R of 1:20 at 70°C for 30 min following protocol by the previous study (Wongkrajang and Surayot 2017). Then, the extract was cooled and filtered through Whatman® filter paper No.1 for further study.

Mordanting procedures
Three different mordant methods used on the cotton fabric were pre-mordanting, meta-mordanting, and post-mordanting. Pre-mordanting method and post-mordanting were carried out by exhausting cotton fabrics in the banana peel extraction at 30, 60, and 90°C by keeping the L:R of 1:50 for 60, 90, and 120 min in the stainless container. Meanwhile, the meta-mordanting was carried out in the different ratios of the banana peel extraction to the marigold flower extraction at 1:1, 1:2, and 2:1 similar to the pre-mordanting and post -mordanting method.

Dyeing procedures
The dyeing process of marigold flower extraction was carried out by the exhaustion method (L:R = 50:1) with three different mordanting methods in the stainless container in the water bath. First, cotton fabrics were dyed at 90°C for 1 h as the previous research (Farooq et al. 2013). Then, the dyed fabrics were rinsed by running water for 10 min and dried at room temperature.

Color measurement
The control and dyed samples were evaluated for color strength using the reflectance method by a Hunter Lab Spectrophotometer (UltraScan VIS). The CIE Lab color coordinates L*, a*, and b* represent lightness, redness -greenness, and yellowness -blueness of color. The color strength (K/S) values at 450 nm were calculated using the Kubelka -Munk Equation (1) (1) Where K is the adsorption coefficient, R is the reflectance of dyed sample and S is the scattering coefficient.
All mordanting conditions were replicated three times. The standard deviation of each sample was calculated. Data were statistically analyzed using the analysis of variance (ANOVA) one-way test and sample difference was analyzed by Tukey' Honestly Significance Difference (HSD) Test at 95% confidence level.

Fastness test
The color fastness to washing and light was tested according to the standard methods, namely, ISO 105-C10:2006 and ISO 105-B02:2014. For evaluation of the fabrics' washing fastness and light fastness, the ratings were given from 1 to 5 and 1 to 8, respectively. The color change of the samples were also measured by the Hunter Lab Spectrophotometer model UltraScan VIS instrument.

Total tannin content
The determination of tannin content from banana peels in different conditions, namely temperature and time was estimated using the standard curve of tannic acid (Table 1). It can be seen the increasing extraction temperature from 30°C to 90°C, the amount of tannin also increased. Therefore, a large amount of tannin content in banana peels was shown at 90°C compared with the other extracting temperature. However, it was found that when increasing the extraction time at 90°C, the tannin content showed the highest amount at 60 min. Consequently, the longer extraction time to 90 min might not benefit the amount of tannin extracted from banana peels because the longer duration of extraction at high temperature caused oxidation of the phenolic compounds (Shirmohammadli, Efhamisisi, and Pizzi 2018). Therefore, the banana peel would be extracted at 90°C, 60 min for using as a biomordant in the further study.

Effect of mordanting temperature
In order to optimize the mordanting parameters, the mordanting temperature was varied from 30, 60 and 90°C at mordanting time of 60 min. Then, these six samples of pre-mordanting and postmordanting conditions were dyed with the marigold flower extraction at 90°C for 60 min. The optimized value of mordanting temperature has been decided according to the highest K/S value of the dyed fabric. Table 2 shows the effect of mordanting temperature on the K/S value of dyed fabric at a constant mordanting time. The increasing the mordanting temperature from 30°C to 60°C showed the significantly improve K/S value; however, the increasing temperature from 60°C to 90°C did not showed the significantly improvement. It is because of an increase in the dyeing temperature leads to an increase in the dye uptake and the kinetic energy between dye and fabric; however, the aggregation decreased with increasing temperature (Baseri 2022). So the highest value of K/S of the premordanting and post-mordanting methods was recorded at 60°C.
The value of L* represented the brightness of the fabric, and it can be seen that both mordanting condition samples were darker when the fabrics were mordanted at a higher temperature. It can be seen the value of b* was far higher than a* and both positive in all samples. It showed the appearance of color closer to yellow more than red color. The mordanting fabric at 60°C in pre-mordanting and post-mordanting conditions showed a higher value of a* than at 30°C and 90°C. Both pre-mordant and post-mordant samples were lower when the temperature increased based on the value of b ×. These values occurred because the biomordant has not changed the natural dyeing process by developing new shades but brighter or darker shades with different tones (Habib et al. 2021).

Effect of mordanting time
The optimization of the mordanting time of the pre-mordanting and post-mordanting method was studied by exhausting cotton fabrics in the mordanting bath in various conditions from 60, 90, and 120 min by keeping the exhausting temperature at 60°C and L:R = 1:50. The mordanted fabric was dyed with the marigolds extraction at 90°C for 1 h. It was found in Table 3 that the samples exhausted for a longer period showed a higher K/S value as the banana peel mordant could form more complex between dye molecules and fabric. However, the decrease in the K/S values with increasing dyeing time can be attributed to the desorption of dye molecules from the substrate (Baig et al. 2021). Similar to the L* value, they gradually decreased, resulting in deepening of shades compared to the only natural dyed sample because tannin produced the darker the color shades of cotton fabric (Ali et al. 2010). As mentioned, the value of b* was far higher than a* and positive in all samples, which showed that the appearance was closer to yellow than red. On the one hand, the color shade of the post-mordanted samples was reddish than the pre-mordanted sample as a* value of the post-mordanted samples was higher than the pre-mordanted sample. This may be because the tannin mordant appeared in red-brown. When applying on the fabric after the dyeing process, the dyed fabric appears in red-brown. On the other hand, the color shade of the pre-mordanted samples was yellowish than the post-mordanted sample as the b* value of the pre-mordanted samples. This may be because the marigold flower extraction was applied after the banana peel mordant. So that, the lutein dye extracted from the marigold flower produced the yellow-orange shades on the fabric. Therefore, it can be concluded that the optimization condition of dyeing cotton fabrics with marigold flower dyed by pre-mordanting and post-mordanting method was carried out at 60°C for 2 h.

Effect of mordanting temperature
The mordanting temperature was also varied from 30, 60, and 90°C by keeping the mordanting duration at 60 min. Table 4 shows the effect of mordanting temperature on the K/S value of dyed fabric at a constant mordanting time. When increasing the temperature from 30°C to 90°C, the K/S value of all mordant-to-dye ratio showed the greater value at 30°C. Although the color strength of all condition decreased gradually, it was not significantly difference from 60°C to 90°C. This is due to the substantivity of the dye decreases when the temperature rises (Tayade and Adivarekar 2013). When increasing mordanting temperature, the dyed fabric at a ratio of 1:1 and 1:2 showed the redder and less yellow as a* value increased. The dyed samples at a ratio of 2:1 presented the greener. The banana peels extraction also played a role as the dye solution, the same as the marigold extraction. Therefore, the quantity of the mordant solution during the meta-mordant process influenced the color strength and the color coordination of the dyed fabrics as K/S value increases when the amount of mordant was increased (Kamel, Helmy, and El Hawary 2009). Based on color strength, it can be concluded that the optimization of the meta-mordanting method was done at 30°C as the K/S showed the highest value at every ratio of the mordant to dye. Especially, the ratio of mordant to dye at 2:1 presented the highest color strength.

Effect of mordanting time
As a result, the mordanting time was varied from 60 to 120 min by keeping the exhausting temperature at 30°C and L:R = 1:50. The color strength and the coordinates L*, a* and b* results obtained from the mordanted and dyed cotton fabrics with natural dyes was shown in Table 5. The K/S value of dyed fabric at a ratio of 1:1 showed the significantly different at 60 min; however, there was no difference between 90 and 120 min. To compare the samples which was the mordant-to-dye ratio at 1:2 and 2:1, it  was found the significantly different at 90 min. However, there was no difference between 60 and 120 min. The dyed samples were lighter when increasing the mordanting time except the mordant-to-dye ratio at 1:2, which showed the increasing of L* value from 60 min to 90 min and the L* value decreased. As shown in Table 5, the quantity of banana peel extraction affected color coordination. When the mordanting solution was greater than the marigold flower dye extraction, the dyed sample showed redder and less yellow as the value of a* of the dyed sample at a ratio of 2:1 was higher, value of b* was lower than the other two ratio. According to the effective process, using shorter time might be the better decision; thus, the optimal time for meta-mordanting time was at 90 minutes for the dyed fabric at a ratio of 1:1 and 60 min for the dyed fabric at a ratio of 1:2 and 2:1.
Moreover, the K/S values were obtained with banana peels mordant and the unmordant fabric were measured at the different wavelength as shown in Figure 1. It was found the value of color depth of shade was slightly different at 400 nm, while it was proximate around 450 nm.

Color fastness
The results show that the wash fastness of marigold dyed cotton fabric without mordanting presented color change of 1 (Table 6). However, using mordant, the color change rating was within 2 to 4.5. Therefore, it can be said that the overall rating of color change was improved, especially the rating of the post-mordanting sample, which was at 4.5. This is because the banana peel extraction applied after  the dyeing process might better form the complex between marigold flower dye and fiber as can be seen in Figure 2.
With light fastness, the unmordanted sample showed a color change rating at 3, similar to the metamordant (Mordant: Dye = 2:1) sample; however, the rating of the others mordanting samples was slightly improved. It might be because of the natural flavonoid chromophore from marigold flower dye is susceptible to photochemical attack (Patel 2011). So, it can be concluded that biomordant was found to be enhanced the wash fastness property, whereas the light fastness property was not been effectively improved.

Conclusions
This research focused on the optimal mordanting condition in the eco-friendly dyeing cotton fabric with marigold flower extraction. The exploiting of banana peel waste as the natural mordant showed the highest amount of tannin at 90°C for 60 min. The optimal condition was at cotton fabrics were exhausted in the marigold flower dye at 90°C for 60 min with the pre-mordanting and post-mordanting methods at 60°C for 120 min. In the meta-mordanting method, the optimal temperature was found at 30°C; however, the optimal time was at 60 for the mordant-to-dye ratio at 1:2 and 90 min for the mordant-to-dye ratio at 1:1 and 2:1. The mordanted cotton fabrics showed the improvement of wash fastness and slightly improvement of light fastness. Further study might focus on the functional properties of the marigold flower dyed fabric using banana peel extraction as the biomordant such as antimicrobial, ultraviolet protection, and anti-fungi properties.

Highlights
• The extraction condition of banana peel waste showed the highest amount of tannin content at 90°C for 60 min. • When dyeing marigold flower extraction at 90°C for 60 min, the optimal mordanting condition of pre-mordanting and post-mordanting methods of the cotton fabric was shown at 60°C for 120 min. • In the meta-mordanting method, the optimal condition was shown at 30°C for 90 min when the mordant-to-dye ratio at 2:1 and 30°C for 60 min at the mordant-to-dye ratio at 1:1 and 1:2. • The cotton fabrics with banana peel mordant dyed with marigold flower extraction showed the improvement of wash fastness and light fastness.

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