Natural dyeing and anti bacterial finishing of cotton fabric with extracts from Justicia schimperiana leaf extract: a step towards sustainable dyeing and finishing

ABSTRACT

The use of non-toxic and eco-friendly natural dyes on textiles has received much attention due to the increased environmental awareness to avoid some hazardous synthetic dyes. In the present study, an eco-friendly approach was developed to impart colour and antibacterial properties to cotton fabrics dyed with Justicia schimperiana leaf extract as a non-toxic natural colourant. The solvent method of extraction and exhaust dyeing method was used for this study. Copper sulphate, ferrous sulphate, and alum were applied in a simultaneous -mordanting process as a mordanting agent. The effects of shade percentage, dyeing temperature, and dyeing time on the obtained colour strength of the fabrics were investigated. Optimisation of dyeing conditions was carried out using Box Behnken design of expert software. An optimum level of 3. 28 colour strength (K/S) was observed in the sample treated with a shade percentage of 50 (% o.w.f), 72 °C dyeing temperature, and 45 minutes of dyeing time. Antibacterial properties of treated fabrics were evaluated against common pathogenic bacteria, Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative). The results indicated the treated fabrics possessed desirable antibacterial properties. The washing and rubbing fastness of the dyed fabrics were also reported.

KEYWORDS:

• Natural dyes
• Justicia schimperiana
• cotton fabric
• antibacterial properties

1. Introduction

Lately, there has been a significant amount of attention given to the practice of colouring textiles using different dyes, as well as the techniques employed to create patterned designs (Bhuiyan et al. 2017; Rajendran and Selvi 2014). This trendy colouring technique is achieved through a process called dyeing, which requires immersing the fabric in a solution containing dyestuffs and other additives (Vankar 2007). Since the discovery of aniline dyes from coal tar, synthetic dyes have become prevalent in contemporary times (Vastrad and Byadgi 2018). It’s estimated that textile industries use more than 10,000 different types of colouring agents, with over 700,000 tons of synthetic dyes being employed worldwide (Haji 2019; Reyes et al. 2018). Despite this, the colouring processes used by the industry are inefficient, resulting in approximately 200,000 tons of these dyes being discharged as effluents into the environment every year (Tesfaye et al. 2015; Zollinger 1987).

Traditionally, textiles were coloured using natural materials that were readily available in the environment. Nature has bestowed a wealth of dye-producing plant species, animals, and minerals that can be utilised for colouring textiles (Bhuiyan et al. 2017; Tesfaye et al. 2015). As Vankar notes, natural colouring agents are obtained from different parts of plants, including leaves, fruits, roots, barks, and so on (Satyanarayana and Chandra 2013; Vankar 2007). In contrast to synthetic dyes, natural dyes sourced from plants and other materials may consist of multiple chemical constituents. These constituents can display a range of colours and properties, either independently or in conjunction with other groups, depending on their functional group, chemical composition, and structure (Ayele et al. 2020). Dyes sourced from plants primarily contain colourants such as flavonoids, anthraquinone, and indigoids (Haji 2019; Patil et al. 2016). Among these, flavonoids are the most commonly found and can be further classified into flavonols, flavanones, and anthocyanins. These flavonoids are responsible for producing a diverse range of brown, yellow, and green hues (Ado et al. 2014).

The practice of utilising natural colourants to dye textile materials has been reintroduced in order to address the environmental issues linked to the use of synthetic dyes (Karabulut and Atav 2020; Shariful Islam, Alam, and Akter 2020). Natural colouring agents are organic compounds that can be derived from sources such as plants, minerals, and insects (Chao et al. 2017). Dyes obtained from these natural sources offer vivid colours, have a strong affinity for textile fibres, are environmentally friendly, and provide a feasible method for dyeing textiles (Tutak and Korkmaz 2012). As a result, there are significant research endeavours underway to develop and utilise these dyes. While similar types of trees may exist in various regions of the world, their physical and chemical characteristics can vary significantly due to their dependence on the evolutionary conditions specific to each region (Davulcu et al. 2014; Shahid, Mohammad, and Mohammad 2013).

Modern extraction methods involve using advanced techniques to extract pigments from natural sources more efficiently. These methods often employ solvents, such as water, alcohol, or supercritical fluids, to extract the colourants from plants, insects, or other natural materials (Habib et al. 2023). Techniques like maceration, steam distillation, ultrasound-assisted extraction, and supercritical fluid extraction are commonly used. Modern extraction methods aim to maximise pigment yield and minimise environmental impact while maintaining the integrity and quality of the extracted natural dyes (Adeel et al. 2023) Mordanting is a crucial step in natural dyeing that involves the application of metallic salts to cotton fabric before dyeing. The purpose of mordanting is to improve colour fastness, enhance dye absorption, and create a chemical bond between the dye and the fabric. Common mordants include alum (potassium aluminium sulphate), iron, copper, tin, and chrome. Mordanting can be done by pre-mordanting (treating the fabric before dyeing) or simultaneous mordanting (adding the mordant to the dye bath) (Yameen et al. 2022)

Cotton fibre is a natural, plant-derived fibre obtained from the seed coat of the cotton plant. It is extensively utilised in the textile industry and is renowned for its comfort and softness, making it a popular choice for clothing and bedding (Buyukakinci, Guzel, and Karadag 2021; Kibria, Chowdhury, Ashik, & Riyad 2022). The fabric possesses excellent breathability, enabling air circulation and moisture evaporation, which contributes to maintaining a cool and dry body. Moreover, cotton is highly absorbent and has the capacity to soak up water up to 27 times its weight. Cotton fibres exhibit remarkable dyeing characteristics, allowing for easy and vibrant colouring with a diverse array of dyes. Consequently, cotton fabrics are available in numerous attractive and lively colours (Gomes and Soares 2023; Manyim et al. 2022). Cotton also possesses a strong affinity for natural dyes, facilitating effective penetration and bonding with the fibre, resulting in vibrant and enduring colour outcomes (Manyim et al. 2022). The porous nature of cotton fibre further aids in its rapid absorption of natural dyes. However, it is crucial to adequately prepare the cotton fabric prior to dyeing to ensure consistent and uniform colour absorption (Bouatay et al. 2016; Sinha et al. 2016)

Earlier research has indicated that Justicia schimperiana leaves can be processed for beneficial purposes for instance for essential oil, anti-inflammatory and antioxidant, Nutrition and biomedical, antioxidant, anti-inflammatory and immunomodulatory functions, pharmaceutics, medical and anti microbial properties (John, Reddy, and Sulaiman 2013). Despite this, there has been no research conducted on utilising Justicia schimperiana for natural dyeing or exploring its antibacterial properties on cotton fabric within the textile industry. This research aims to assess the feasibility of extracting natural dyes from Justicia schimperiana located in Wolkite, Ethiopia, and to investigate the dyeing capacity and antibacterial activity of these dyes on cotton fibres. The findings of this study provide novel insights into the potential ways of utilising different parts of Justicia schimperiana for beneficial purposes in the textile industry.

2. Materials and methods

2.1. Materials

2.1.1. Justicia schimperiana leaf

For the purpose of this investigation, Justicia schimperiana leaves obtained from Justicia schimperiana plant in Wolkite city were utilised to extract natural dyes.

2.1.2. Fabric

To conduct the dyeing experiments, a bleached cotton fabric with a plain weave was utilised. The fabric had a mass per unit area of 142 g/m2 and had 68 ends per inch and 50 picks per inch.

2.1.3. Chemicals

To fix the dyes onto the fabrics and create a range of colour shades, analytical grade aluminium sulphate/alum, copper sulphate, copper chloride, zinc chloride, and ferrous sulphate were employed as Mordant’s. None of the chemicals were subjected to purification prior to use.

2.2. Methods

2.2.1. Extraction of natural dyes

The gathered materials were dried naturally at room temperature and then finely ground using a laboratory-grade grinding machine. The colouring agent was extracted from the powdered material through an aqueous extraction technique by boiling it in distilled water at 100^○C for 40–60 minutes. The specific ratios of material to water used are detailed in Table 1. The boiled materials were filtered through nylon fabric as shown in Figure 1, and the solutions obtained were employed to dye the fabric. The residual material was subjected to two more extractions to obtain the maximum yield of colourant. The filtrate obtained was used for both identification and dyeing of cotton fabric.

Figure 1. (a) Raw, (b) dried, and (c) extracted solution.

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Extraction process of justica shimbriana plant. Figure a is the raw leave collected from local areas, Figure b is the crushed leaves mechanically, Figure c indicates the extracted solution from all experimental runs.

Table 1. Extraction recipes for justica schimperiana dye extracts.

Time(minutes)	Temperature(^0C)	pH	MLR
60	85	6.5	1:20
60	90	6.5	1:20

2.2.2. Dyeing process

The cotton fabric was tinted with the powdered dye generated from the leaf of Justicia schimperiana. The samples were then dyed with different extracts for a set amount of time, temperature and shade percentage. All parameters were fine-tuned to achieve the highest possible dye bath exhaustion, optimal shade, and superior colour fastness.

2.2.2.1. Experimental design for dyeing

Box Behnken design experiment software was used for designing the experimental runs for the natural dyeing of cotton fabric with Justicia schimperiana leaf extract. The dyeing factors were dyeing temperature, dyeing time, and shade percentage. The response was colour strength.

The process of dyeing cotton fabrics is depicted in Figure 2. Prior to the dyeing procedure, the fabric samples were soaked in hot water to ensure even penetration of the dye molecules. The dyeing process using the Justicia schimperiana leaf extract was conducted at 70–90^○C for 40–60 minutes, respectively. The dyed samples were then rinsed with cold water to eliminate any unfixed dyes. The approach employed for mordanting and other follow-up treatments was described in detail in the earlier sections. Following the dyeing process, mordanting was carried out using ferrous sulphate, aluminium sulphate, and copper sulphate at room temperature for 10 minutes.

Figure 2. Dyeing process for fixing justica schimperiana onto cotton fabric.

The dyed fabric underwent further treatment, whereby it was boiled for 10 minutes in the presence of a standard solution of 5 g/l soap and 1 g/l sodium carbonate to eliminate any surface-bound

Dye molecules. Next, the fabric was rinsed with water for 10 minutes at room temperature to fully remove any soap and carbonate residues. Finally, the dyed fabric was dried for 5 minutes using a forced airdryer.

2.2.3. Colour strength of dyed cotton fabric

The Greta Macbeth Colour Eye 3100 spectrophotometer was used to measure the reflectance of the dyed samples. The colour intensity of the samples was assessed by determining the ratio of absorption (K) and scattering (S) coefficients (K/S) using the spectrophotometer’s built-in software sequencer.

2.2.4. Evaluation of colour fastness

Colour fastness was evaluated in accordance with the ISO 105-C06 A1S:2010 standard. A fabric sample measuring 4 × 10 mm was subjected to a standard soap solution at a concentration of 5 g/l with a material liquor ratio of 1:40 for 45 minutes at 50^○C using an Auto wash machine (manufactured by Medsan, Italy). The washed samples were then rinsed extensively with cold water, and the degree of staining was evaluated using a grey scale.

2.2.5. Light fastness evaluation of dyed samples

To assess the light fastness of the naturally coloured samples, the ISO 105-B02:2013 standard was followed. The Solar box Xenon Arc Light Fastness Tester (manufactured by Medsan Lab, Italy) was used to conduct the test. The fabric specimen’s light fastness was evaluated by exposing it to sunlight for 10 hours at an average temperature of 30^○C, after which it was compared to the grey scale.

2.2.6. Crock fastness evaluation of dyed samples

The rubbing fastness of the dyed samples was determined using a crock metre manufactured by Medsan, Italy, in accordance with the ISO 105-X12:2016 standard test method.

2.2.7. Anti-bacterial finishing process

The cotton fabric was subjected to an anti-bacterial process using an extract solution through an exhausted method. This treatment was applied to both half-bleached and dyed cotton fabric. The effectiveness of the treatment was evaluated by testing the fabric’s ability to inhibit the growth of gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli) using the AATCC 100 method. The growth of bacteria was investigated using the agar well diffusion test, which relies on the following equation.

$w=\left(T-D\right)/2\dots \dots \dots \dots \left(1\right)$

Where: W is width of clear zone of inhibition in mm, T is total diameter test specimen and clear zone in mm D is diameter of the test specimen in mm

3. Result and discussion

3.1. Extraction of natural dyes

The purified samples were crushed and dissolved in water, followed by boiling in a hot

Water bath for 60 minutes at a constant MLR of 1:20 to facilitate quick extraction. At the end of each extraction cycle, the total colour was extracted using 96% ethanol. The solution was then filtered twice using nylon fabric to prepare it for dyeing. After the extraction process was complete, the remaining residue was dried, and its mass was measured and recorded as shown in Table 2. The aqueous extracted dye had a pH level above 5, indicating it was slightly basic. However, all the extracted dyes showed low acidity, which varied depending on the sample source. The acidic pH of the dye extracts may be attributed to the presence of acidic components such as gallic acid or tannic acid, along with other colouring compounds present in each sample

Table 2. Extraction yield of natural dye.

S no.	Time(min)	Temperature(^0C)	Weight of powder before extracted (g)	Weight of sludge after extracted(g)	Extraction Yield (%)
1	60	90	10	5	50
2	60	90	10	5	50
3	60	85	10	4.6	54
4	60	90	10	5	50
5	60	90	10	5	50
6	60	85	10	4.6	54
7	60	90	10	5	50
8	60	85	10	4.6	54
9	60	90	10	5	50
10	60	90	10	5	50
11	60	85	10	4.6	54
12	60	90	10	50	50
13	60	85	10	4.6	54
14	60	90	10	5	50
15	60	85	10	4.6	54
16	60	85	10	4.6	54
17	60	90	10	5	50

The optimal extraction conditions for obtaining the highest yield of dye from Justicia schimperiana leaves were found to be 90°C for

4. Minutes, resulting in a maximum yield percentage of 55%

Experiment numbers 6 and 17 had higher percentage yields compared to the other experiments conducted. Therefore, experiment 6 and 17 are considered preferable due to their higher percentage yields, indicating better efficiency as shown in Figure 3.

Figure 3. Extraction yield percentage.

4.1. Dyeing of cotton fabric

According to Table 3, cotton fabric dyed with various dye extracts resulted in different shades. The dye extracts from Justica shmbriana produced attractive shades ranging from light yellowish to darker scarlet shades. Table 3 displays 17 different combinations of dyeing temperature, dyeing time, and shade percentage used to determine colour strength. The colour strength of each dyed fabric was evaluated using the colour eye 3100 after the dyeing process was completed. The results of the colour strength for the dyed fabrics are presented in Table 3.

Table 3. Experimental design for dyeing.

Run	A:temperature(^oc)	B:time(min)	C: dye con.(o.w.f)	pH	MLR	colour strength(k/s)
1	80	60	20	6.5	1:20	3.48
2	80	50	35	6.5	1:20	3.08
3	70	50	20	6.5	1:20	2.89
4	70	40	35	6.5	1:20	2.66
5	70	60	35	6.5	1:20	2.64
6	80	50	35	6.5	1:20	3.09
7	80	40	20	6.5	1:20	2.65
8	90	50	20	6.5	1:20	2.75
9	90	50	50	6.5	1:20	3.59
10	90	40	35	6.5	1:20	3.25
11	80	50	35	6.5	1:20	3.09
12	90	60	35	6.5	1:20	3.45
13	80	50	35	6.5	1:20	3.07
14	70	50	50	6.5	1:20	3.06
15	80	40	50	6.5	1:20	3.13
16	80	50	35	6.5	1:20	3.08
17	80	60	50	6.5	1:20	3.41

Table 4 presents the analysis of variance (ANOVA) for the response variable of colour strength in terms of K/S. The ANOVA results show that the model used to analyse colour strength in terms of K/S is significant, as indicated by the Model F-value of 6.94. The probability of obtaining such a large F-value by chance alone is only 0.50%. The model terms A, B, and C are significant, as indicated by their p-values being less than 0.0500. Model terms with p-values greater than 0.1000 are considered not significant. In this case, the Lack of Fit F-value of 85.44 implies that the lack of fit is not significant relative to the pure error, which is a good thing. Therefore, the model was well-fitted to the data. If there are many insignificant model terms, reducing the model may improve its overall performance.

Table 4. ANOVA for selected linear model.

Source	Sum of Squares	df	Mean Square	F-value	p-value
Model	0.8606	3	0.2869	6.94	0.0050	Significant
A-temperature	0.4005	1	0.4005	9.69	0.0082
B-time	0.2080	1	0.2080	5.03	0.0429
C-dye con.	0.2520	1	0.2520	6.10	0.0282
Residual	0.5373	13	0.0413
Lack of Fit	0.5370	9	0.0597	85.44	<0.0001	Not significant
Pure Error	0.0003	4	0.0001
Cor Total	1.40	16

4.1.1. The effect of temperature on color strength

Based on Figure 4 it can be observed that an increase in temperature leads to an increase in colour strength. There is a strong positive correlation between temperature and colour strength. Temperature is a crucial factor in the dyeing process, as high temperatures can cause chemical degradation of dyes, while low temperatures may result in incomplete dyeing (Dhanania, Singhee, and Samanta 2022). The maximum colour strength of 3.59 was achieved when the temperature was increased from 70°C to 90°C, as shown in Table 4. Dyeing cotton fabrics with justice schimperiana leaf extract dye solution demonstrated that higher dyeing temperatures resulted in increased colour strength (K/S value). This could be due to an increase in the kinetic energy of dye molecules, leading to enhanced dye diffusion and aggregation, and/or an increase in the rate of dye penetration into the fibres.

Figure 4. The effect of temperature on color strength.

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The effect of temperature on color strength of dyed fabric sample. As the temperature increases the color strength also increases this due to the increase in rate of diffussion.

4.1.2. The effect of reaction time on color strength

The processing time is a critical parameter in the dyeing process, as both excessively long and short dyeing times can lead to negative effects on the colour outcome (Atav 2023; Tayade and Adivarekar 2013). Prolonged exposure to heat can result in dye material decomposition, while short dyeing times may lead to incomplete dyeing. Table 3 shows that the maximum colour strength of 3.59 was achieved when the processing time was increased from 40 to 60 minutes. Figure 5 illustrates the impact of dyeing time on the colour strength of the dyed fabric, with an increase in reaction time resulting in higher colour strength values. As dyeing time increases, the colour strength value continues to rise until the dye exhaustion attains equilibrium.

Figure 5. The effect of reaction time on color strength.

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As the reaction time increases the color strength also increases this is due to the increase in the rate and degree of exhaustion until equilibrum point.

4.1.3. The effect of shade percentage on color strength

Increasing the dye concentration in the dye bath results in more dye molecules being available to attach to the fibres, leading to higher K/S values with deep shades (Aminoddin Haji, Shahmoradi Ghaheh, and Mohammadi 2023) as shown in Table 3. Figure 6 shows that the maximum colour strength of 3.59 was achieved when the concentration was increased from 20 % to 50 %. Dyeing cotton fabrics with justice schimperiana leaf extract dye solution demonstrated that increasing the dye concentration resulted in increased colour strength (K/S value).

Figure 6. The effect of dye concentration on color strength.

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The effect of dye concentration on color strength as the shade percentage increases the color strength also increases this is due to the increase in dye migration.

4.2. Fastness properties of the dyed fabrics

Table 5 shows the fastness properties, including light fastness, rubbing fastness, and wash fastness, of the dyed fabric using different Mordants. All three Mordants used in the study demonstrated excellent fastness properties, with alum performing slightly better in terms of wash fastness than the other Mordants for both dyes. However, the un-mordantand natural dyed samples exhibited poor fastness properties, which could be attributed to the fabric’s properties that bind the dye molecules in the form of hydrogen bonding and Vander Waals forces.

Table 5. Shades of dyed cotton fabrics with dye extracts from Justica shmbriana.

Mordant	Nomordant	Coppersulphate	Alum	Ferroussulphate
Shade

The colour of the undyed cotton fabric is pure white

4.2.1. Wash fastness

The type of mordant used is a critical factor that influences the colour fastness properties of naturally dyed cotton fabrics, as it affects the association between the dye and fibre. Most of the naturally dyed samples exhibited excellent wash fastness grades, except for those using alum mordant, where wash fastness was only fairly good (3/4) as shown in Table 6. From these results, it can be concluded that the use of a mordant is necessary to fix the extracted dye onto the fabric and to improve its wash fastness properties. Among all the dyed samples, those treated with CuSO₄ and FeSO₄ using justica shmbriana showed very good wash fastness. The washing fastness property of natural dye is significantly affected

Table 6. Fastness properties of dyed samples.

Mordant	Wash fastness	Light fastness	Rubbing fastness
			Wet	Dry
FeSO4	4/5	7	4/5	4/5
CuSO4	5	8	4/5	5
Alum	3/4	6	4/5	4/5

by the rate of dye diffusion and the state of the dye inside the fibre (Tayade and Adivarekar 2013).

4.2.2. Light fastness

As with the previous study, the light fastness properties of naturally dyed fibres are significantly influenced by the type of mordant used. Regardless of the mordant type, the fastness to light of naturally dyed fabrics was very good, except for dye mordant and with Alum, where it was good (6). Moreover, the rate and extent of colour change for the dyed fabrics were greater with Ferrous and copper sulphate Mordants.

4.2.3. Fastness to rubbing

The dry colour change to rubbing of the dyed fabrics was found to be good and all Mordants, with a rating of 4/5, and good in wet conditions with a rating of 4/5. The changes in rubbing fastness may be due to the water-soluble dye group, which makes them more susceptible to detachment from the fabric (ISO, B 2010).The fastness analysis results indicated that mordanting produces a higher colour depth relative to non-mordantand samples. This can be attributed to the additional dye sites provided by the mordanting process. This may be explained by the fact that natural colouring agents contain ionisable groups such as -OH and CO2H (Hamdy, Hassabo, and Othman 2021). In aqueous solution, these -OH groups become soluble due to their conversion into anionic systems. Mordants with metal ions with vacant orbital’s of the suitable energy have the ability to create complexes between the fibre, mordant, and dye molecule known as chelate that shifts the natural dye and is most effective with natural fibres (Samanta 2020; Samanta and Konar 2011; Sanjeeda and Taiyaba 2014).

4.3. Proposed mechanism of dyeing

It is important to note that the majority of natural dyes do not have substantivity to all kinds of textile fibres without the use of a mordant (Gupta 2019). Most natural extracted dyes require a mordant, which can be obtained from a natural source or manufactured, preferably in the form of a metal salt or suitably coordinating complex-forming agent, in order to create an affinity between the fabric and the extracted colouring agent or pigment molecules of natural dyes as shown in Figure 7 (Gupta 2019; Samanta et al. 2009). Metallic salts, as a mordant, can affect the shade and depth of the blank samples and form metal complexes with the fibres and dyes (Samanta 2020; Saxena and Raja 2014). After mordanting, the metal salts anchor to the yarn/fabric, attracting the dye molecules to be anchored to the textile material and finally creating a bridging link between the colouring agent’s main functional group and the fibre by forming coordinating complexes (Kasiri and Safapour 2014) as shown in Figure 9.

Figure 7. Chemical structure of oxy-cis-henokiresinol in Justica shmbriana plant (John, Reddy, and Sulaiman 2013; Singh and Srivastava 2017).

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Justica shimbriana plant contains oxy-cis henokiresinol chemical structure in its native structure form.

Copper sulphate Mordants are well-known for their ability to form coordination complexes and readily chelate with the dye. As the coordination number of copper sulphate is 6, some coordination sites remain unoccupied when they interact with the fibre. Functional groups, such as hydroxyl groups on the fibre, can occupy these sites (Patel 2011; Samanta and Konar 2011). Thus, a ternary complex can be formed in which one site binds with the fibre and the other site binds with the dye. Such a strong coordination tendency can enhance the interaction between the fibre and the dye, resulting in high dye uptake (Hamdy, Hassabo, and Othman 2021; Kanchana et al. 2013) as shown in Figure 8. This leads to higher K/S values, which indicates greater colour strength.

Figure 8. Proposed dyeing mechanism of cotton fabric and dye extracted from the justica shmbriana.

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Dyeing Mechanism of cotton fabric with the given natural dye. The presence of tannins and saponins are responsible for the proposed dyeing mechanisms of cotton fabric through justica shmbriana.

Figure 9. Proposed mordanting mechanism of cotton fabric and dye extracted from the justica shmbriana.

4.4. Antibacterial activity

The effectiveness of the fabric in killing bacteria was tested by exposing it to two different types of microorganisms, Staphylococcus aureus and Escherichia coli, which were obtained from the American Type Culture Collection (Jothi 2009; Preethi et al. 2020; Sathishkumar, Sneha, and Yun 2010). The method used to evaluate the antibacterial activity was to measure the zone of inhibition (Ennaceur et al. 2022). To prepare the fabric sample, it was sterilised by autoclaving at 121 degrees Celsius for 15 minutes. Bacterial suspensions of S.aureus and E.coli were created, and 200 micro litres of each were added to the glass cup containing the fabric sample. The sample was then incubated at 37 degrees Celsius for 24 hours. After incubation, 10 micro litres of each sample were taken and incubated for another 24 hours. The results showed the antibacterial activity of different untreated and treated fabrics, which are shown in Figures 10, 11 and 12.

Figure 10. Anti –bacterial activity of control fabric.

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Anti bacterial activity of control fabric this is the anti bacterial activity of untreated samples for both gram posetive and gram negative bacterias.

Figure 11. Anti –bacterial activity of dyed fabric.

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Anti bacterial activity of dyed samples this is the anti bacterial activity of treated or dyed samples for both gram posetive and gram negative bacterias.

Figure 12. Anti –bacterial activity of dyed fabric after 5 wash cycle.

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Anti bacterial activity of dyed samples after 5 wash cycles this is the anti bacterial activity of treated or dyed samples after serious of 5 wash cycles.

According to the results of the agar well diffusion test, the finished fabric exhibited antibacterial activity against both Staphylococcus aureus and Escherichia coli, with a zone of inhibition of 13 mm and 12 mm respectively. This indicates that the presence of flavonoids and tannins in the leaf extract contributed to a reduction in bacterial growth on the finished fabric. However, after subjecting the fabric to 5 wash cycles, the zone of inhibition decreased to 11 mm and 10 mm for Staphylococcus aureus and Escherichia coli respectively. This suggests that the antimicrobial finish became less effective as the number of wash cycles increased, likely due to a reduction in the durability of the finish. Further research is necessary to develop a more durable antimicrobial finish for the fabric.

4.4.1. Proposed mechanism of anti bacterial finishing

The results of the experiment showed that the treated fabric was effective against both gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli), as it prevented their growth and killed them. In contrast, the control fabric had large colonies of bacteria, as seen in Figure 10. The presence of tannin and flavonoids in the leaf extract of the Justicia Schimperiana plant contributed to the antimicrobial properties of the treated fabric, as these compounds are known to have antimicrobial properties (Khurshid et al. 2015; Pawar, Bagatharia, and Thaker 2005). This is consistent with literature that suggests that natural dyes containing compounds like tannin, flavonoids, and quinonoids often possess high medicinal activity due to their inherent antimicrobial properties (Bang et al. 2007; Hebeish et al. 2011; Purwar and Joshi 2004).

5. Conclusion

The research consisted of three phases. In the first phase, natural dye was extracted from the leaf of the Justicia Schimperiana plant, and the extraction yield was characterised. The maximum extraction yield was found to be 55%. In the second phase, cotton fabric was dyed with the extracted leaf solution, and the effect of dyeing temperature, dyeing time, and shade percentage on colour strength was analysed. The recommended dyeing conditions were a dyeing time of 45 minutes, a dyeing temperature of 72 ◦c, and a shade percentage of 50 % o.w.f. The colour strength of the optimised sample was found to be 3.28. In the last phase, the antibacterial activity of the antimicrobial finished fabric was evaluated, and it was found to be effective against both Staphylococcus aureus and Escherichia coli, with a zone of inhibition of 13 mm and 12 mm respectively. Overall, the study successfully applied dyeing and antimicrobial finishing of cotton fabric with Justicia Schimperiana leaf extract.

Authorship contribution statement

Worku Tegegne: Writing- original draft, Adane Haile:Supervision, Methodology, yerdawu zeleke, writing and editing, Yohannes Temesgen: Lab. Work, Editing, Siltanu Biyable: - review & editing, Haymanot Bantie: Lab. Work, Review

Acknowledgments

The authors express their sincere appreciation for the technical assistance provided by the college of engineering and technology, at Wolkite University in Wolkite, Ethiopia.

Disclosure statement

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

Data availability statement

The datasets used and/or analysed during the current study are available from all authors upon reasonable request.

Additional information

Notes on contributors

Worku Tegegne

Worku Tegegne is a senior lecturer and researcher at wolkite university, He obtained his Bsc and Msc degree in 2019 and 2022 respectively from Bahir Dar University. His work has been Published in several prestigious sciencetific journals and he has recieved numerous awards for his contribution in the field.

Adane Haile

Adane Haile Associate is a distingushed researcher who has made significant contribution in the field, He has held a senior researcher position at Bahir Dar University. With a wealth of knowledge and experience, Associate Professor Adane Haile has authored numerous papers that have been published in reputable journals. Associate Professor Adane Haile’s commitment to advancing knowledge and his dedication to mentoring students have made him an invaluable asset to the academic community.

Yirdawu Zeleke

Yirdawu zeleke is a senior researcher at wolkite univeristy and now he is a PHD candidate at ITMO university, Russia. He holds a chair position in the Department of textile engineering. Yerdawu’s work has been published in leading journals in his feild and he has presented his findings at international conferences. He is passoniate about teaching and mentoring students in undergraduate and postgraduate level.

Yohannes Temesgen

Yohannes Temesgen was a researcher at wolkite univeristy. He obtained his Bsc degree from wolkite university in 2023. He is passionate about doing researches and community service activities.

Haymanot Bantie

Haymanot Bantie was a researcher at wolkite university in the depertment of textile engineering, he obtained his Bsc. degree from wolkite Univerisity in 2023.

Siltanu Biyable

Siltanu Biyable was a researcher at wolkite univeristy in textile engineering department. He obtained his Bsc degree from wolkite Univeristy in 2023.