2.1 MATERIALS AND CHEMICALS

2.2 METHODS

2.2.2 Dyeing

2.2.2.1 Natural dyeing

Natural dyeing was performed according to our previous work (figure 1) ^{(Repon et al., 2016a, 2016b}. ^2016c). Briefly, dyeing had carried out conferring to exhaust method by Infra-red lab sample dyeing machine (XIAMEN RAPID, China) at 100°C for 60 minutes. Then the dye bath was cooled at 40°C and samples were washed at room temperature. Then soaping was performed for removing unfixed dye form the fabric surface by 0.5 g/L ISO standard soap at 80 °C for 10 minutes. In case of dyeing and soaping, material to liquor ratio maintained as 1:20. Samples were squeezed and dried in fíat dryer machine (MESDAN, Italy).

Fig. 1 Process curve of natural dyeing. 

2.2.2.2 Reactive dyeing

Recipe of reactive dyeing is tabulated in table 2 to match the shade with the natural dyed specimens.

Table 2 Recipe of reactive dyeing of 100% cotton knitted scoured blea.ched fabric. 

Chemicals/	Amount
Parameters
Soda ash	5g/L
Glauber salt	15g/L
Leveling agent	1g/L
Remazol Red RR	0.0119% (on the weight of
	fabric)
Remazol Blue RR	0.0096% (on the weight of
	fabric)
Remazol Yellow RR	0.0520% (on the weight of
	fabric)
Material: Liquor	1:10
Temperature	60°C
Time	30 minutes

Reactive dyeing was carried out according to the process curve mentioned in figure 2 by maintaining the above recipe. The unfixed dyes were removed from the dyed fabric surface with 1 g/L soaping agent (GASOP-100 RUBY) for 10 min at 80°C.

Fig. 2 Process curve of reactive dyeing. 

3.1 FIXATION OF DYE ONTO FIBER SURFACE

Figure 3 indicates the FTIR-ATR spectra of scoured bleached (1), natural (2) and reactive dyed (3) cotton fabric. Table 3 denotes the adsorption bands for imparting color into fabric. Various peaks appears approximately at 435-560cm-l, 620-680 cm-1, 1000-1210 cm-1, 1315-1387, 1420, 1640-1660 cm-1, 2838-2915 cm-1, and 3270-3330 cm-1 for OH out of plañe bending, glycoside linkage and asymmetric out of phase ring stretch of C1-O-C4, C-H bending, di-alkyl ether linkage (C-O-C) and -C-0 symmetric stretching of cellulose, hemicellulose and lignin content , absorbed water vibrations, -CH stretching vibrations and corresponding to hydrogen bonded -OH stretching vibrations respectively ^{(Miller &Wilkins, 1952)}. For natural dyed specimens (2) major changes were appeared at 703.27, 780.32, 1173.71 and 1616.19 cm¹ due the presence of inorganic salts in banana floral setm sap into viz. potassium chloride, sodium phosphate and magnesium chloride respectively ^{(He, et al., 2007: Monteiro, Margem, Loiola, Assis & Oliveira, 2014)}. Peaks at 1056.62 correspond C-H and C-O deformation band ^{(Ibrahim, Dufresne, El-Zawawy & Agblevor, 2010)} and 1396 cm^J was responsible for CH deformation of -CH2-^{(Bashar, Siddiquee & Khan, 2015; Khandare, Kabra. Tamboli & Govindwar, 2011)}. For natural dyed fabric (2), stronger bands were seen at peaks 431.4, 521.4, 607.9, 665.4, 1160.2, and 1427cnr¹ correspondingly than control (1) by decreasing transmittance % due to presence of inorganic salts, tannin, flavonoid, lignin, etc (figure 5) ^{(Ibrahim et al., 2010)}.

Fig. 3 FTIR-ATR, spectra of cotton (1) scoured bleached, (2) dyed with banana sap, (3) dyed with reactive dye. 

For reactive dyed samples (3), weak peaks were observed at HOO-MOOcm^-1 for ethar linkage between reactive dye and cellulose ^{(Bashar et al., 2015)}. It is evidient that peaks 1542.4 and 1627.9 are responsible for N-H deformation of vinyl sulphone (β sulfato ethyl sulfone group) reactive dye (figure 4) . Band at 1727.9 was looked for C=0 of ketone ^{(Khandare et al., 2011)}.

Fig.4. Molecular structure of vinyl sulphone Reactive dye. 

Fig. 5 Molecular structurc of Tannin and common flavonoids of banana floral sap. 

3.2. CMC VALUE

Table 4 embodies the CMC report considering natural as standard and reactive as batch sample. Figure-6 denotes the photographs of BFS sap dyed and Reactive dyed fabric. CMC decisions were accepted as "Pass" for illumination D65 10 degree where difference (DE CMC) was 0.45. Difference in lightness, redness, yellowness, chroma and hue angle were detected as 1.19, -0.05, -0.03, -0.05 and 0.04 respectively. The sample dyed with reactive dye was resembled as slightly lighter than the natural dyed specimens. More green and more blueness were also observed in reactive dyed sample but less dye saturation. Metamerism was not observed in prescribed settings.

Fig 6 Photographs of natural and reactive dyed samples  

3.3 DEGREE OF COLOR LEVELNESS

Homogeneity of dye molecule distribution onto the fiber surface essentially indicates the levelness of color. The natural and reactive dyed samples were showed excellent color levelness (table 5) . Natural dyed specimens were 88% level as compared to reactive dyed samples.

In reactive dye bath, electrolyte and leveling agent are usually used to overeóme the inherent inharmonious spreading of dye molecules onto the fiber surface. Conversely, no leveling agents were required for natural dyeing to produce similar color levelness ^{(Repon et al., 2016a, 2016b}, ^2016c). That means over all more level color were yielded for BFS sap.

3.4 COLOR FASTNESS

Table 6 represents the results of color fastness to wash, water and perspiration andshows the color fastness to rubbing and light of natural and reactive dyed samples respectively. Excellent upshots were recorded for reactive dyed cotton samples regarding wash, water and perspiration (both in acid and alkali) fastness.

The natural dyed samples showed very good rating of color fastness to washing, water and perspiration. Regarding wash fastness, slightly color changes were observed onto cotton, polyamide and wool portion. Concerning water fastness, little staining was witnessed onto polyamide and wool part of multi fiber fabric. Color staining was appeared onto cotton for acid perspiration. For alkaline perspiration color staining was looked onto cotton and polyamide.

Inherently, both reactive dye and cotton deliver anión into water thus repulse one another. The positive rings onto cellulose surface are generated due to the addition of electrolyte in the dye bath and stronger covalent bond formed between cellulose and reactive vinyl sulphone) P sulfato ethyl sulfone) group. Consequently, reactive dyed samples exhibit excellent fastness grading ^{(Repon et al.. 2016c)}. In contrast, BFS comprises of many organic and inorganic compounds ^{(Monteiro et al., 2014)}. From the máximum absorption wavelength (Amax= 350nm), it can be presumed that the color appeared in the dyed samples is liable for flavonoids ^{(Pinheiro & Justino, 2012)}. Tannin of BFS dye has excellent dye molecule cross linking performance via co-ordination bond onto the cellulose surface that was conformed from the FTIR-ATR spectra. So, almost equivalent color durability (washing, water and perspiration) were observed for natural dyed cotton alike reactive dye. Excellent behaviors were noticed for dry and wet rubbing fastness (Table 7) of reactive dyed cotton. For natural dyeing, dry and wet rubbing fastness were graded as very good i.e. 4 and modérate i.e. 3-4 respectively. These observations also express that for stronger binding ability between reactive dye and fiber is favorable for excellent color durability to rub. Conversely, the weak co-ordination bond between natural dye and fiber exhibited modérate upshot ^{(Ali, 2007)}.

Regarding light fastness, the ratings were recorded as 2-3 i.e. poor to fair for natural dyed specimens. Oppositely, 3-4 i.e. fair to modérate ratings were appeared for reactive dye samples. Higher light fastness (Table 7) properties of reactive dyes can be attributed for more intra molecular H bond. This enhances the stability of the dye compound by reducing the electrón density at chromospheres. Therefore, the sensitivity of dye toward photochemical oxidation was reduced ^{(Ali, 2007)}. Alternatively, such strong interaction is not present in the bonding between natural dye and cotton fabric. So the natural dyed specimens were exhibited inferior light fastness property than reactive dyed specimens. Thus, both natural dyed and reactive dyed samples were comparable for color durability without light fastness properties ^{(Ali, 2007)}.

3.5 EFFLUENT PARAMETERS

Table 8 shows the various parameters of effluent for natural and reactive dyeing separately.

BOD, COD, TDS, TSS, Color and pH of reactive and natural dyeing effluent were found as 153, 427, 1210, 112 mg/L, 2100 Pt Co and 8.5 and > 1000, 7303, 9800, 1490 mg/L, 20920 Pt Co and 6.8 respectively. Almost all effluent parameters of reactive dyeing were lower than the DoE standard except color and pH. This is oceurred for using of less amount and few auxiliary chemicals compare to commercial dyeing process ^{(Khan, Islam & Khalil, 2014)}. Though valúes of effluent parameters of natural dyeing were higher than DoE standard but it is not a matter of headache for environmental pollution for their biodegradability aspect ^{(Khan et al., 2014)}. The higher valué of TDS and TSS of natural dye effluent were ensued because of the co-existence of metal and organic compound in banana sap. Lower color contení appeared in reactive dye bath for greater absorption% of dye for improved affinity of cotton towards reactive dye molecules and addition of electrolyte. Conversely, higher color content observed in the bath of natural dyeing for lower exhaustion of molecules and zero use of auxiliary chemicals for improving dye-fiber interaction.

3.6 COSTINO

Table 9 shows the comparative cost of natural and reactive dyeing process for one kg fabric. In case of producing similar shades, cost of natural dyeing was noticed much lower than reactive dyeing.

Because, after harvesting of banana fruit, banana plants leads huge amount (89%) of waste ^{(Repon et al.. 2016a)}. Moreover, no auxiliary chemicals were used in natural dyeing bath. Therefore, only processing cost and negligible amounts of extraction charges are applicable. Conversely, reactive dyeing was associated with more dyes, auxiliary chemicals and processing costs. Dyeing cost of cotton fabric with banana floral stem sap were also less than that of henna leaves, acacia bark and turmeric bark ^{(Ali, 2007; Umbreen, Ali, Hussain & Nawaz, 2008)}. Furthermore, as BFS dye is fully safe so it has zero effluent treatment cost. Interestingly, we didn't use and additional water in main dyeing process. Only few amount of water was engaged for removing unfixed dye from the fabric surface. So negligible water treatment plants cost is applicable for the BFS dye. Additionally, the process of cotton dyeing with BFS sap didn't include various prolong steps as typical commercial process ^{(Rahman, Biswas, Mitra & Rakesh, 2014)} which reduces the dyeing time wittily. Furthermore, various harsh chemicals in reactive dyeing are responsible for machine corrosión that leads machine depreciation cost ^{(Karmakar, 1999)}. In this regards, BFS sap is fully safe for machinery and it will reduce the equipment's depreciation cost ingeniously. Thus, BFS dye reduced dyeing cost almost half of the synthetic dye.