Per-acetic acid effect on separation of banana fiber and their dyeing with natural dyes

Abstract

The fiber derived from the pseudo-stem of the banana plant is the subject of this investigation. It describes the processes involved in creating pseudo-stem fiber from bananas, such as fiber extraction, retting, and degumming. Banana fiber has been separated using per-acetic acid. To evaluate the efficacy of the process, the fiber's appearance and form have been altered. A homogeneous, spotless surface was observed under Scanning Electron Microscopy. Weight loss is the outcome of the treatment and absorbency increases. 3.66% of the weight loss is attributed to the per-acetic acid treatment. The fiber’s average diameter was reduced 81.9% compared to the raw fiber. Fourier transform infrared spectroscopy analysis was utilized to assess the chemical changes brought about by the treatment, which verified the presence of cellulose in the fiber. The separated fibers were colored using natural dyes, which were then assessed based on how well they characterized the color. The results demonstrated the use of natural colors derived from extracts of madder and myrobalan. The standard test indicates that ferrous sulfate (FeSO₄) exhibits strong resistance to light, washing, and rubbing fastness, making it a viable mordant for achieving brown to black color.

Introduction

The production of textiles is increasingly being influenced by the concepts of environmentally friendly and sustainable development. These ideas are not wholly novel in the textile industry. Over time, numerous natural and eco-friendly textile processing techniques have become more advanced. Many scientific and technological initiatives have been made to create environmentally friendly procedures in order to preserve a link with the ecosystem. However, substitute materials need to be considered. Significant advantages of natural fibers include their low density, appropriate mechanical properties, high disposability, and renewability. This study suggests that banana pseudostem, a waste material left behind after harvest and a consequence of banana fruit farming, could be used as a natural fiber source for textile manufacture. Natural fibers include banana fiber. After harvest, the remaining materials in the field may be utilized to make goods that might be sold to the socioeconomic sector [1, 2].

Billions of tonnes of stems and leaves are wasted annually from banana farms after the bananas are harvested. The manufacturing of other natural and synthetic fibers requires less energy, fertilizer, and chemical inputs because of the readily available supply of fibers produced by such waste [3]. Since synthetic fibers are harmful to the environment, finding nontraditional sustainable textile supplies is vital to provide an effective answer [4, 5].

One of the most crucial post-fabric treatments used to increase the fabric’s marketability is dyeing. The customer’s selection of visual hue for the fabric is invariably skewed. However, the concerns with wastewater discharge are made worse by the usage of hazardous chemicals during the dyeing process. To make the process environmentally friendly, it is becoming more and more important to look into dyeing with natural resources [6–11]. Finding numerous references to their usage of banana cloth proved to be challenging [12]. Natural dyes are non-substantive and can be made from a variety of plant parts. Mordents are therefore necessary in order to get around their intrinsic disadvantage of having a narrow color spectrum. Many plant parts can be used to make natural colors, although they are insubstantial. To overcome their intrinsic color range limitation, mordents must be used. Nonetheless, an effort has been made to overcome this constraint in this study [13–15].

The main objective of this project is to look at easy, low-cost methods of adding value through recycling banana plant waste. The main constitutents of bananan fiber is Cellulose (31.27 ± 3.61), Hemicellulose (14.98 ± 2.03), and Lignin (15.0 ± 0.66) [16] which makes the fiber harsh and rigid. A recent study by Chattopadhyay et al. [17], described a low-temperature, low-alkali method of peracetic acid (PAA) bleaching of banana fiber that is fiber-friendly. In this article, banana fiber has been separated and purified using an environmentally friendly method. The morphological features, physical attributes, and chemical makeup of the fibers are examined. SEM microscopy was used to examine the fiber’s morphology. Utilizing FTIR spectroscopy, the isolated fiber's chemical composition was examined. Lastly, in order to add value, the extracted fibers were dyed using two natural dyes Myrobalan and Madder to create a range of shades. The dyed samples were then examined using the CIELab system to determine their color characteristics and fastness.

Materials and methods

Materials

Banana raw material

Sheaths of banana plant were collected from Gujarat, India’s Bharuch district. The fibers from the bananas were removed mechanically. To facilitate the fiber extraction process, a cutter machine can split the pseudostem into two or four halves. These are the sections that makeup sheaths. These sheaths are transferred from the cutter machine to the raspador equipment. The pseudostems of banana trees are decorated, or the fiber is removed, using this simple instrument. Following their passage through an extraction machine called a mechanical decorticator, the pieces are mechanically stripped of their fibers [1].

Dyes and chemical

The natural dyes were extracted in a laboratory using an aqueous extraction technique, i.e. Myrobalan (Terminalia chebula) (NDI) extracted as per the method reported by Patel et al. [9]. The active groups present in the NDI were Gallic acid, Glucodallin, Pyrogallol, and Ellagic acid. The natural dye, Madder (Rubia Cordifolia) (NDII) was extracted using the process reported by Patel and Kanade [18]. The active chromophoric groups present in this dye were Xanthopurpurin and Pseudopurpurin.

The in-house synthesized Per-acetic acid (CH₃COOOH) was used. The Per-acetic acid was prepared using a process reported by Chattopadhyay and Chavan [19].

Metal salts like Ferrous sulfate (FeSO₄, 7H₂O), Copper sulfate (CuSO₄, 2H₂O), Alum (Al₂(SO₄)₃, 2H₂O), and Stannous chloride (SnCl₂, 7H₂O) were used as mordents. Acetic acid, Caustic soda (NaOH), non-ionic detergent, and Soda ash (Na₂CO₃) were used as process auxiliaries supplied by Suvithinath Laboratories, India. All other compounds employed in this research were of LR grade and used without additional purification.

Methods

Several contaminants, including gum, lignin, dust, dirt, and several other agricultural pollutants, can be found in raw banana fiber. Therefore, to get pure cellulose, it is important to eliminate all of these contaminants using processes like beating, cleaning, alkali treatment, bleaching, etc. The pretreatment process is described in the following order;

Pretreatment of raw banana fiber

Initially, sticky material and other contaminants were removed from raw banana fiber using a wooden rod. Cleaning is only done mechanically with a comb before being subjected to alkali treatment. Following beating and cleaning, the banana fiber was treated with a 5% (owf) caustic soda solution and a 2% (owf) (Lisapol N) non-ionic detergent solution according to the recipe below. On a gas hob for one hour at 80 °C, the alkali treatment was finished. After that, tap water was used to properly wash the banana fibers many times. The process flow is described in the following Fig. 1.

Fig. 1 [Images not available. See PDF.]

Preparatory processes flow chart for banana fiber separation

Bleaching treatment

Using hydrogen peroxide and per-acetic acid alternately, a bleaching process was carried out to increase the degree of whiteness of the fiber and eliminate the self-coloration of banana fiber caused by lignin and other compounds.

In–house preparation of per-acetic acid: All of the chemicals used in the study, including the anhydrous acetic acid (AA), potassium permanganate, sodium thiosulfate, 30% hydrogen peroxide (HP), sulfuric acid, potassium iodide, and others, were purchased locally and were analytically pure. Vacuum distillation of 30% HP produced a higher concentration of HP. Less than 0.5 × 10⁻⁶ gpl of metallic ions were present in the system of the reaction. The tests were conducted using deionized water. In the clean round-glass stopper flasks, 1 molar AA and 1% (v/v) of 98% sulfuric acid were added before the reaction. After that, 0.5 molar of HP solution was added and well-blended. The system was kept at a constant temperature in a water bath. Samples were quickly gathered and examined in a set amount of time [19].

Two-step bleaching process: The bleaching process consists of two steps. Step 1 involved treating the fiber with the formulation shown in Table 1 using produced per-acetic acid, and Step 2 involved treating the fiber with hydrogen peroxide at 80 ℃ for 1 hour. The samples were then carefully cleaned, neutralized with weak hydrochloric acid, and rinsed one more before drying.

Table 1. Formulation of bleaching bath

Recipe (Step:1) Per-acetic acid Bleaching
Per-Acetic acid	15 gpl
MLR	01:20
Temperature	Room temperature
Time	1 h
Recipe (Step:2) H2O2 Bleaching
H2O2 (3%)	15 gpl
Sodium silicate	15 gpl
Soda Ash	20 gpl to maintain pH- 10–11
MLR	01:20
Temperature	80 °C
Time	1 h

Morphological analysis of banana fiber by scanning electron microscopy (SEM)

A scanning electron microscope, model JSM-5610 LV from Japan, is used to describe the size, shape, and morphology of a material’s surface. The SEM displays incredibly detailed three-dimensional images at noticeably greater magnifications (up to × 300000) than a light microscope (up to × 10000). But because no light waves were utilized in their creation, they are only available in black and white.

Scanning electron microscopy was used to observe the surface morphology of treated and untreated fiber. Images of the surface structure of fiber composites, fracture surfaces, natural particles, and chemical coating are extremely clearly visible through SEM imaging. SEM is the correct method to analyze the treated and untreated fibers textile substrate because it can provide images with a resolution of 1–5 nm. Instead of utilizing visible light, transmitted electrons were used to create SEM images, which can achieve a resolution of up to 100A^o and magnification of up to 100,000 X. There were created Computerized records of the scanned images at various magnification and resolution levels.

FTIR (Fourier transform infrared spectroscopy) analysis

Banana fiber’s chemical makeup was examined using FTIR (Kbr pellet technique FT-IR 8400S spectrophotometer, Shimadzu, Japan). The method is based on the fact that a chemical compound exhibits strong, selective infrared (IR) absorption. After absorbing IR radiation, a chemical substance’s molecules vibrate at a variety of speeds, creating tightly packed absorption bands known as the IR absorption spectrum, which will correlate to the distinctive functional groups and bands found in a chemical substance. A chemical substance’s IR spectrum can be used to identify it as a result.

Dyeing of banana fiber with natural dyes

Aqueous extraction of natural dye

In the current study, two natural colors, one from the Myrobalan fruit and the other from the Madder plant’s roots were extracted using distilled water. Natural extracts of NDI and NDII were prepared as per literature by Patel [9] and Patel and Kanade [18] respectively. To make a 1 L stock solution, accurately weighed 100 gm powder from each unique natural source and was pasted with 5 ml of T. R. oil and the remaining distilled water. To ensure that the stock solution was free from lumps and aggregates of solid ingredients, the solution was further boiled for 2 h and then filtered through fine cotton fabric. This solution was applied throughout the investigation.

Application of natural extract to the textile substrate

The exhaust dyeing was done in a laboratory-scale six-hole dye bath (Paramount, India) that had a set temperature. 10, 20, and 30% (owf) of the required amounts of NDI and NDII extract were added to the dye baths, sodium carbonate was added to the dye bath to maintain the liquor's pH at 8.5, and metallic mordants such as ferrous sulfate, copper sulfate, and stannous chloride were added to the dye bath at a rate of 6.0% (owf). The quantity of metal salts was used as per the permissible limits by CPCB: Guide manual: Water and Wastewater analysis. With water, the material-to-liquor ratio was kept at 1:50 for the dyeing process. Starting at room temperature, the dyeing process takes ten minutes. Gradually, raise the bath’s temperature till it reaches boiling while continuing to color the water for one hour. After dyeing the sample was neutralized with dilute H₂SO₄ (1%) rinsed thoroughly and dried under shade.

Color characterization of dyed banana fiber

The Spectra scan 5100 (RT) spectrophotometer (Premium Color Scan Instruments, India) is used to measure color. It was used to test the dyeability of banana fiber in terms of color strength (K/S) and color coordinate (L, a, b, C, H) values.

The dyed sample was examined for colorfastness using methods that adhered to ISO standards. In particular, the ISO 105-CO3 test for colorfastness to washing determined using launder o meter (Paramount Scientific Instruments, India), ISO 105-BO2 (1990) test for colorfastness to light evaluated using Fad-o-meter device with a xenon arc lamp (FDA-R, Atlas, USA), and ISO 105X12 (2002) test for colorfastness to rubbing on Crock Meter (Paramount Scientific Instruments, India) were all utilized.

Results and discussions

The results of testing on agricultural waste banana fiber are summarized in this publication. Extracted banana fibers were subjected to an alkali treatment to remove non-cellulosic components (such as sticky compounds), hemicelluloses, and lignin. The fiber’s natural color components were also lost during the subsequent bleaching process.

This study’s primary goal is to investigate simple, cost-effective ways to add value by transforming trash from banana plants. In this article, an innovative green technique has been used to separate and purify banana fiber. The shape, physical characteristics, and chemical composition of the extracted banana fiber were studied. The FTIR spectroscopy method was also used to analyze the chemical makeup of the extracted fiber.

By treating the prepared material with natural resources, its functioning was further improved. By using the proper process, the prepared material's absorbency and feel were assessed. Broadly speaking, this is covered in two segments: (1) Extraction and analysis of separated banana fiber by a novel green method, and (2) Further enhancing its aesthetics and functionality by treating the separated fibers with natural resources.

Effect of per-acetic acid on separation of banana fiber

Even after scouring, the natural fibers and fabrics still have naturally existing coloring matter. The flavones in the banana bloom may be responsible for this brown and yellow coloring. In varying degrees, the soil, dryness, and frost can all contribute to yellowness. Oils and greases from harvesting or processing equipment, as well as dirt, dust, and insects, may also contribute to color. By using bleaching chemicals to remove the coloring material from the fiber with the least amount of fiber damage, the goal of bleaching is to create white fiber shown in Fig. 2. The effectiveness of both processes, assessed in terms of yellowness, whiteness, and brightness index (Table 2), has been tested in this study utilizing traditional bleaching with (H₂O₂) and a green approach employing per-acetic acid.

Fig. 2 [Images not available. See PDF.]

Unbleached and bleached banana fibers

Table 2. Characteristics of pretreated banana fiber

Sample	K/S	Whiteness	Yellowness	Brightness	Image of fibers
Raw fiber	1.856	55.084	45.994	24.637
Alkali treatment	1.014	60.080	33.712	31.246
Per-acetic acid bleached	0.167	84.067	10.144	68.331
H2O2 bleached	0.111	85.701	7.938	71.330
Softening	0.118	84.187	11.712	67.941

Consumers today are demanding more environmentally friendly products. A similar tendency is also seen in the textile sector. In this context, the textile processing sector considers reduced water use, energy efficiency, and processing using green or organic chemical compounds. Per-acetic acid is a liquid chemical substance that has no color. Commercial per-acetic acid is an equilibrium mixture of per-acetic acid, acetic acid, hydrogen peroxide, and water. Per-acetic acid is not toxic to the environment because it decomposes into acetic acid and oxygen. Acetic acid is also 100 percent biodegradable.

Two-stage bleaching is used to bleach natural cellulosic fiber, particularly for bast fibers. To achieve a suitable level of whiteness, hypochlorite bleaching was used in the first step, followed by hydrogen peroxide. It has been discovered that materials that are initially bleached using per-acetic acid rather than hypochlorite achieve a suitable level of whiteness with significantly less harm to the fiber and appear to be softer. In this experiment, in-house manufactured per-acetic acid was employed in addition to commercial per-acetic acid. To prevent the wasteful degradation of ready-made per-acetic acid, it was synthesized using hydrogen peroxide and glacial acetic acid in 1:2 molar ratios or manufactured on-site. Controlling pH is crucial in all cases.

Effect on whiteness, yellowness, and brightness of banana fiber

A material’s capacity to give other materials color is gauged by its color strength. This characteristic, which can be stated as a color strength value, is characterized by the absorption in the visible portion of the spectrum. The results of measuring the impact of conventional and green pretreatment on banana fiber are shown in Table 2. From the results it can be seen that the color strength values (K/S) of raw fiber were found to maximum i.e. 1.9, gradually as the treatment proceeded towards alkali treatment followed by H₂O₂ Bleached the K/S values reduced indicating the color of the fiber shifted towards white. In the case of pretreatment with per-acetic acid i.e. green process the fiber becomes pallid, compared to the raw and alkali treated fiber. The softening process further decreases the color strength value of the fiber.

From Table 2, it can also be seen that the whiteness index of the fiber improved from raw fiber < alkali treated < Per-acetic acid Bleached < Softening < H₂O₂ Bleached. In the case of the yellowness index opposite to the whiteness index trend was observed. The maximum value of the brightness index was observed in the case of banana fiber treated with the conventional pretreated sample.

The banana fiber in its raw form contains several impurities i.e. lignin, gum, and many others which were removed by subsequent pre-treatments. The maximum weight loss that occurred at alkali treatment was 26%. After the alkali treatment, weight loss during the peroxide bleaching process was less than 11%, and the overall weight loss was 36.37%. The maximum weight loss that occurs during alkali treatment may be due to the removal of lignin, gum, extracts, and pectin content of the fiber, which gets soluble in alkali, resulting in weight loss. In the case of the bleaching process, only coloring matters are removed, resulting in less reduction in weight. The per-acetic acid treatment contributes a minimum weight loss of 3.66% compared to the conventional bleaching process.

Effect of PAA treatment on the morphology of banana fiber

Using the SEM technique, the surface morphology of banana fiber has been studied at various pretreatment phases. Images taken at different magnifications display the contour and surface of banana fiber. The surface of fibers and changes to fiber surfaces as a result of the subsequent procedure may be examined very well using scanning electron microscopy (SEM).

Figure 3, depicts the SEM micrograph of untreated, raw banana fiber. It is clear from the figure that the fiber surface contains waxes and oils as well as other surface contaminants. These contaminants give fibers a layer of protection, which may eventually increase fiber strength and reduce absorbency.

Fig. 3 [Images not available. See PDF.]

Scanning electron micrographs of raw banana fibers

The surface morphology of banana fiber after alkaline treatment is shown in Fig. 4. The contaminants that were present on the surface of raw fiber have been eliminated as a result of the alkali treatment, as can be seen clearly from the fiber surface under various magnifications. The sticky components shown on the surface of raw fibers in the SEM image don’t appear to be present on the alkali-treated fiber's surface.

Fig. 4 [Images not available. See PDF.]

SEM micrographs of banana fiber treated with alkali

Figure 5, depicts images of per-acetic acid-bleached banana fiber. When seen at different magnifications, the surface of the fiber can be observed to have improved since the previous stages of processing; specifically, the alkali treatment caused the surface to become free of gummy materials, and other impurities.

Fig. 5 [Images not available. See PDF.]

SEM images of Banana fiber bleached with a per-acetic acid green process

Four magnified SEM images of banana fiber treated with a typical H₂O₂ bleaching agent are shown in Fig. 6. In comparison to the previous stage of alkali pretreatment, the surface of the fiber seems to be extremely clean, free of gummy substances, and separated from one another. The individual fiber also appears to be more separated, transparent, and whiter than the fiber treated with the green process. The scanning electron microscope (SEM) image of banana fiber in its natural state reveals an average diameter of 110.5 µm. The fiber’s average diameter decreased to 22.7 µm as a result of the subsequent alkali pre-treatment, representing a reduction of 79.46%. Following the alkali treatment, there was a decrease in diameter of 20 µm during the per-acetic acid bleaching process. The fiber's diameter was reduced by 81.9% in total. The decrease in the diameter of the fiber could be attributed to the disconnection of individual fibers from the banana stem. From the literature and our experimental work, it can be confidently concluded that the traditional approach outperformed the alternative in terms of fiber separation and fiber cleaning. The green process, however, can be considered as the potential process with the optimal performance in terms of separation and cleaning of individual fiber, according to the morphological images of banana fiber that were taken after each stage of the conventional process with H₂O₂ and with the green single stage per-acetic acid process.

Fig. 6 [Images not available. See PDF.]

SEM images of banana fiber bleached with H₂O₂

Effect of PAA on the chemical composition of banana fiber

The composition of solids, liquids, and gases is revealed by the influence of per-acetic acid on the FTIR spectrum. Infrared spectroscopy is a crucial technique in organic chemistry for identifying the presence of specific functional groups in a molecule. This technique creates spectra with patterns that reveal structural information, allowing one to determine the functional group that is present in a molecule or chemical. A distinct spectral imprint is left behind by every chemical molecule or substance.

The spectra pattern obtained through FTIR analysis has been shown in Fig. 7a–d of raw banana fiber, alkali-treated fiber, hydrogen peroxide bleached, and per-acetic acid bleached fiber banana fiber respectively.

Fig. 7 [Images not available. See PDF.]

a FTIR spectra of raw banana fiber. b. FTIR spectra of alkali treated banana fiber. c. FTIR spectra of H₂O₂ bleached banana fiber. d. FTIR spectra of per-acetic acid treated banana fiber

Figure 7a represents the FTIR spectrum of raw banana fiber. The hydrophilic tendency of raw banana fibers is reflected in the broad absorption band at the 3700 cm⁻¹ region due to the presence of –OH groups as the main component. The zigzag nature of the peak indicates scattered cellulose units. The peak at 2830–2695 cm⁻¹ is due to aliphatic saturated C-H stretching vibration in hemicelluloses and cellulose. The peak at 1740–1724 cm⁻¹ in fiber is due to acetyl (C=O stretching) and ester groups of hemicelluloses, pectin, and lignin. The peak at 1070–1030 cm⁻¹ is due to the S=O stretching present in the sulfoxide group. The peak at 600–500 cm⁻¹ indicates the presence of a C–Br group strong alkyl halide. The peak at 500–450 cm⁻¹ is due to the presence of the Si–O-Si bending vibration group.

FTIR spectrum of alkali-treated banana fiber is given in Fig. 7b. The peak values 3650–3400 cm⁻¹ signify the presence of –OH stretching groups which is responsible for its hydrophilic nature. The peak at 2960–2850 cm⁻¹ is due to aliphatic saturated C-H stretching vibration in hemicelluloses and cellulose.

Figure 7b represents absorption peaks and corresponding groups present in the fiber after alkali pretreatment. The efficiency of the alkali treatment can be evaluated by subtracting the FTIR spectrum from the raw banana fiber. It can be seen from Fig. 7c that the pectin, gummy material, as well as lignin, are removed from the alkali-treated banana fiber.

Figure 7c represents the FTIR spectrums of samples cleaned with conventional H₂O₂ bleaching process. The changes that occurred in chemical composition due to the conventional pretreatment can be determined by the changes in the spectrum of raw fiber and finally treated fiber. Absorption wavelength shows the groups present in the conventionally bleached banana fiber. The peak at 3000–2840 cm⁻¹ is due to aliphatic saturated C-H stretching vibration in hemicelluloses and cellulose. The peak at 1600–1450 cm⁻¹ is due to the C-H stretching of the aromatic ring. The peak at 1342–1266 cm⁻¹ is due to the C-N stretching of aromatic amine. The peak values at 1150–1085 cm⁻¹ are due to the presence of C-O stretching which signifies the presence of cellulose, hemicelluloses, and lignin. The peak at 690–515 cm⁻¹ is due to the C–Br stretching of the halo compound.

Figure 7d represents the corresponding groups of FTIR peaks. The hydrophilic character of the peak values, 3700–3587 cm⁻¹, is due to the presence of -OH stretching groups. The presence of the Nitro molecule N–H stretching group is what causes the peak at 1550–1500 cm⁻¹. The presence of aromatic amines with the C-N stretching group is what causes the peak at 1342–1266 cm⁻¹. Since the C–Cl stretching halo compound is present, the peak at 850–550 cm⁻¹ results. The peak for lignin does not appear in Fig. 7d indicating their removal from the per-acetic acid bleached banana fiber.

Effect of PAA treatment on the color characterization of banana fiber with natural dyes

In this study, pretreated banana fiber was dyed with two natural dyes namely, Madder and Myrobalan, at 10% owf shade using the exhaust dyeing technique. Meta-mordanting technique was employed for mordenting the banana fiber with three metallic mordents namely, CuSO₄, FeSO_4, and Al₂(SO₄)₃. Table 3 displays the outcomes in terms of color intensity and color coordinate values.

Table 3. Colour strength and color coordination of dyed banana fiber

Sample	K/S	L	a	b	C	H	Image of fibre
Raw Banana fibre	1.97	56.02	5.04	12.73	13.70	68.38
ND I 10% (owf)	2.70	59.01	3.77	14.68	15.15	75.57
NDI 10% (owf) + FeSO4 (6% owf)	6.17	56.60	3.72	12.55	13.09	73.46
ND I 10% (owf) + CuSO4 (6% owf)	10.30	64.18	1.72	17.90	17.98	84.46
ND I 10% (owf) + Al2 (SO4)3 (6% owf)	2.51	64.35	2.29	17.55	17.70	82.55
ND II 10% (owf)	1.87	40.09	8.11	− 3.48	8.83	33.76
ND II 10% (owf) + FeSO4 (6% owf)	5.75	49.32	8.48	7.25	11.16	40.49
ND II 10% (owf) + CuSO4 (6% owf)	3.65	41.88	10.50	1.48	10.60	8.00
ND II 10% (owf) + Al2 (SO4)3 (6% owf)	1.32	44.64	19.02	4.49	19.54	13.29

The images of dyed fibers and color coordinate values of samples dyed only with natural dyes exhibit a light brown color with Myrobalan extract and medium brown with the Madder extract. The shades of individually dyed samples were changed with the use of individual metallic salts. In the case of Myrobalan when used with CuSO₄ as mordant it can be seen from the image that the color strength value increases and the color is changed to dark brown. Light brown or beige color is obtained with Al₂(SO₄)₃ as mordant and with FeSO₄ as mordant giving a dark brownish-black color on banana fiber.

The tones of the colors produced by various metallic mordents with each natural extract vary. Because “tannin” is the primary contaminant in NDI extract, this may be the cause. A tannin-metal ion combination was created when this tannin and the metal ion interacted. For instance, a dark brown color tannin-metal ion complex was created when tannin and ferrous sulfate combined. Depending on the strength of the binding between the dye and metal ion, dark and bright colors were produced. Different mordants can produce a wide range of colors (in various tones and hues), which may be because tannins are present. These tannins are phenolic chemicals that can chelate with various metals to produce a variety of colors. In addition to changing tannins’ light sorption properties; a treatment with metal salts has the potential to render them water-insoluble [20]. As a result, they are fixed to the textile substrate. In addition to these processes, it is hypothesized that the tannins in the dyes may connect with cellulose in the ways listed below.

The phenolic hydroxyl group of the tannin forms hydrogen bonds with the hydroxyl and carboxyl groups of other polymers; Ionic bonds form on the tannin between appropriately charged anionic groups; Covalent bonds are created when any quinone groups interact with the tannin and the appropriate reactive groups in the other polymer [21].

Similarly, in the case of NDII extract when used with individual mordants gives different shades i.e. with CuSO₄ as mordant dark brown; with Al₂(SO₄)₃ as mordant reddish brown, and with FeSO₄ as mordant gives dark brown color on banana fiber as seen from the color coordinate data and corresponding images given in Table 3.

Madder’s roots are richer in color. The roots contain dye present in the free or bound glucosides which are anthraquinone derivatives, mainly purpurin (CI-75410) and munjistin (CI-75370). The roots also contain a small amount of xanthopurpurin (CI-75340), pseudopurpurin (CI-75420), nordamncanthal, and rubiadin. Ferrous sulfate, which is well known for its capacity to form coordination complexes, rapidly chelated with the dye in this experiment, as shown in Table 4. Since ferrous sulfate has a coordination number of 6, several coordination sites were vacant when it interacted with the fiber. These positions can be occupied by functional groups such as amino and carboxylic acid groups in dye and -OH groups on the fiber. With the fiber on one side and the dye on the other, this metal can create a ternary complex [20–22]. Aluminum sulfate creates weak coordination complexes with the dye; these complexes tend to make relatively strong connections with the dye but not with the fiber, preventing the dye from interacting with the fiber [18].

Table 4. Fastness ratings for washing, Light, and rubbing of dyed banana fiber with natural dyes

Sample	Light	Washing	Rubbing
			Dry rubbing	Wet rubbing
Myrobalan 10% (owf)	5–6	3	3–4	3–4
Myrobalan 10% (owf) + FeSO4 (6%)	6–7	3–4	3–4	3–4
Myrobalan 10% (owf) + Cu SO4 (6%)	6	3–4	4	3–4
Myrobalan 10% (owf) + Al2 (SO4)3 (6%)	6–7	4	4	4
Madder 10% (owf)	5	2–3	3	3
Madder 10% (owf) + FeSO4 (6%)	5–6	3	3–4	3
Madder 10% (owf) + Cu SO4 (6%)	5–6	3	3–4	3–4
Madder 10% (owf) + Al2 (SO4)3 (6%)	6	3–4	4	4

Since banana fiber is cellulosic, it contains many active sites where a dye can bind. The -OH groups on the ends of the polymer may establish covalent or ionic bonds with it, giving rise to important colorimetric and fastness features. The chemistry of dyes bonding to fiber is quite intricate. By creating a chemical bridge between the dye and the fiber, the mordant aids in the binding of dyes to fiber, increasing the substantiveness of a dye as well as the fabric’s color fastness and color depth.

Table 4 displays the color’s resilience to external agents, including light, regular laundering, and rubbing against external surfaces. Both the applied natural dyes show overall moderate to very good efficacy against the light, washing, and rubbing fastness properties when evaluated through standard methods. The use of metallic salt not only enhanced the overall fastness ratings but also changed the shades of the sample dyed without the mordents. The change in shade due to the use of mordant may be attributed to the fact that the mordant is “metallic salts” that are used in natural dyeing to help set the dye pigment and improve color and light fastness. The word comes from the Latin word “mordere” meaning “to bite”. The type of mordant used changes the shade obtained after dyeing and also affects the fastness property of the dye.

Sustainable aspects of PAA treatment on banana fiber

The idea of sustainable development and environmental friendliness is now influencing how textiles are made. In the textile sector, these concepts are not particularly new. The variety of natural and environmentally friendly textile methods has improved with time. To maintain links with the ecosystem, several attempts have been undertaken in science and technology to create environmentally friendly procedures. In this prospect use of in-house prepared PAA in the pretreatment of banana fiber should be considered as a sustainable alternative process.

Natural fibers offer significant benefits such as low density, suitable mechanical characteristics, high disposability and renewability, and acceptable stiffness. This study suggests using leftover banana trunks as a fiber source in the textile manufacturing process to popularize a natural fiber option that is a by-product of banana fruit cultivation. After harvest, the banana pseudo stem is a waste product. A natural fiber is banana fiber. The leftover materials that are left in the field after harvest can be used to create it extremely cheaply. For the successful commercialization and to add value by enhancing its aesthetic value without compromising the ecological aspect of this work, the separated fibers were dyed with two natural resources i.e. Myrobalan and Madder extract.

Conclusion

The main objective of this study was to explore the potential of banana fiber as a valuable functional material for various industries, including medical, cosmetic, and textile-related sectors. The separation of banana fibers was achieved through a modified approach that incorporated environmentally friendly technologies. Green peracetic acid can be used to separate banana fiber.

In the initial part of the study, banana fibers were isolated and purified using a green technique and in-house produced per-acetic acid. It is evident from the SEM pictures that the surface of the fibers has achieved a higher level of uniformity and is free from impurities. As a result of the treatment, the fiber’s color changes to white. In terms of whiteness, the traditional H₂O₂ bleaching procedure proved to be more effective. FTIR measurement confirms the higher intensity of cellulose. The conventional technique proved to be the most effective in achieving whiteness, while the green per-acetic acid method remains a viable option for separating and cleaning banana fibers. Two natural dyes can be used to effectively color the banana fibers, enhancing their visual appeal. The use of green chemicals for pretreatment and natural dye to color the fiber simplifies the process and makes it cost-effective for adding value by converting waste obtained from banana plants.

Author contributions

B. H. Patel: Conceptualization, Methodology, Data curation, Formal analysis, Software, Validation, Project administration, Writing – review & editing. D. P. Panchal: Investigation, Methodology, Data curation, Formal analysis, writing. S.B.Chaudhari: Project administration, Supervision, Validation, Review & editing.

Funding

This work has not supported by any funding agencies.

Data availability

All data pertaining to this work will be made available on reasonable request.

Declarations

Competing interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

References

1. Mohiuddin, AKM; Saha, MK; Hussion, S; Ferdoushi, A. Usefulness of banana (Musa paradisiacal) waste in manufacturing of bio-products a review. Agric; 2014; 12, 1 pp. 148-158.

2. Deka, B; Deka, P; Borgohain, R. Exploration of banana fiber as low cost ecofriendly waste management. Asian J Bio Sci; 2014; 9, pp. 129-130.

3. Al Mamun, MA; Hasan, MM; Ali, MF; Shafiur Rahman, GM. Eco-friendly treatment of green banana fiber in compared to chemical treatment. J Mater Environ Sci; 2021; 12, 6 pp. 823-826.[COI: 1:CAS:528:DC%2BB3MXisVKis7rP]

4. Zhang, Y; Lu, X; Gao, BC; Lv, W-J; Yao, J-M. Preparation and characterization of nano crystalline cellulose from bamboo fibers by controlled cellulase hydrolysis. J Fiber Bio Engg Info; 2012; 5, 3 pp. 263-271. [DOI: https://dx.doi.org/10.3993/jfbi09201204]

5. Nadanathangam, V. & Satyamurthy, P., Preparation of Spherical Nanocellulose by Anaerobic Microbial Consortium. 2^nd International Conference on Biotechnology and Food Science, IPCBEE. 2011; vol.7, Singapore.

6. Patel, BH. Clark, M. Natural dyes. Handbook of textile and industrial dyeing; 2011; Cambridge, Woodhead Publishing: pp. 395-424. [DOI: https://dx.doi.org/10.1533/9780857093974.2.395]

7. Desai, K; Patel, B. Eco friendly preparatory processing of cotton textiles. Asian Dyer; 2021; 18, 4 pp. 26-33.

8. Patel, BH; Shah, SR. Novel approach for single stage green dyeing and antifungal finishing of wool fabric. Asian Dyer; 2014; 11, 5 pp. 25-30.

9. Patel, BH; Agarwal, BJ; Patel, HM. Dyeing of nylon with Acacia Arabica wild bark extract. Text Asia; 2002; 33, 9 pp. 34-42.

10. Patel, BH. Studies on waste minimization and reproducibility of a natural dye. Colourage; 2009; 56, 6 pp. 91-96.[COI: 1:CAS:528:DC%2BD1MXovFOlsL4%3D]

11. Agarwal, BJ; Patel, BH. Reincarnation of natural colourants. Chem Weekly; 2000; 45, 38 pp. 139-148.

12. Singh, PP; Sharma, D. Application of madder natural dye on banana fiber. Inter J Home Sci; 2020; 6, 2 pp. 1-3.[COI: 1:CAS:528:DC%2BB3cXitFGgu7bM]

13. Patel, BH; Patel, PB. Dyeing of polyurethane fibre with Ocimum sanctum’. Ind J Fib Text Res; 2006; 31, 3 pp. 474-476.[COI: 1:CAS:528:DC%2BD28XhtFWqtbfK]

14. Hosseinnezhad, M; Gharanjig, K; Iamin, H; Rouhani, S; Adeel, S. Environmentally dyeing of wool yarns using of combination of myrobalan and walnut husk as bio-mordants. Progress Color, Colorants Coat; 2023; 16, 2 pp. 197-205.[COI: 1:CAS:528:DC%2BB3sXksFymt7s%3D] [DOI: https://dx.doi.org/10.30509/pccc.2022.167001.1177]

15. Patel, KJ; Patel, BH; Naik, JA; Bhavsar, AM. Eco- friendly dyeing with Tulsi leaf extract. Man-made Text India; 2002; 45, 11 pp. 420-425.[COI: 1:CAS:528:DC%2BD3sXisVGltbk%3D]

16. Mukhopadhyay, S; Fangueiro, R; Arpaç, Y; Şentürk, Ü. Banana fibers-variability and fracture behaviour. J Eng Fib Fab; 2008; [DOI: https://dx.doi.org/10.1177/155892500800300207]

17. Chattopadhyay, SN; Samanta, KK; Ammayappan, L; Ghosh, RK. Peracetic acid bleaching of banana fibre: process optimisation. Color Technol; 2023; 139, 6 pp. 678-688.[COI: 1:CAS:528:DC%2BB3sXksVanurY%3D] [DOI: https://dx.doi.org/10.1111/cote.12681]

18. Patel, B; Kanade, P. Sustainable dyeing and printing with natural colours vis-à-vis preparation of hygienic viscose rayon fabric. Sust Mat Tech; 2019; 22, e00116.[COI: 1:CAS:528:DC%2BB3cXjvFajsQ%3D%3D] [DOI: https://dx.doi.org/10.1016/j.susmat.2019.e00116]

19. Chattopadhyay, DP; Chavan, RB. Per-acetic acid- an eco friendly bleaching agent. Ind J Fib Text Res; 2003; 28, pp. 456-461.[COI: 1:CAS:528:DC%2BD2cXmvFWqtg%3D%3D]

20. Patel, B; Kanade, P. Iron-tannin complex effect on coloration and functional properties of silk fabric. Sust Chem Pharm; 2021; 22, 100490.[COI: 1:CAS:528:DC%2BB38XhtlSrtL%2FL] [DOI: https://dx.doi.org/10.1016/j.scp.2021.100490]

21. Patel, BH; Agarwal, BJ; Solanky, DD; Panchal, JJ. Improving the environmental and economic aspects of cotton dyeing using vegetable dyes. Colourage; 2006; 53, 3 pp. 49-58.[COI: 1:CAS:528:DC%2BD28XktFWnsLc%3D]

22. Patel, BH; Agarwal, BJ; Patel, HM. Novel padding techniques for dyeing babool dye on cotton. Colourage; 2003; 50, 1 pp. 21-26.[COI: 1:CAS:528:DC%2BD3sXitVCjt7k%3D]