Reactive dye chemistry plays a crucial role in the dyeing of cotton fibers. Herein, to provide insight on the adaptability of salt-free reactive dyeing for sustainable environmental development, the effect of dye chemistry on the dyeing properties of cotton fibers in the proposed EtOH–CCl4–H2O ternary solvent system was investigated in detail. Twelve commonly used reactive dyes were selected as representative dyes and applied to cotton yarns based on their reactive groups, molecular weights, chromophores, and sulfonate groups. Compared with the conventional aqueous dyeing method, almost all reactive dyes showed an enhanced dyeing performance in the EtOH–CCl4–H2O (55:40:5) mixture. Dyeing results of cotton yarns indicated that the investigated copper phthalocyanine dyes and azo dyes are suitable dye categories for dyeing in the EtOH–CCl4–H2O mixture. This study may offer a theoretical strategy for the industrial-scale production of cotton fibers using the developed solvent assisted dyeing technology. The organic solvents recovery will be carried out in the future study.
Research Article
Salt-free reactive dyeing of cotton fibers in a ternary solvent system with different reactive dye chemistry
https://doi.org/10.21203/rs.3.rs-1949200/v1
This work is licensed under a CC BY 4.0 License
You are reading this latest preprint version
Cotton fiber
cellulose
EtOH–CCl4–H2O mixture
reactive dyes
molecular structure
dyeing properties
Cotton, an important industrial crop, has been applied by mankind for thousands of years (Cai et al., 2017; Song et al., 2020; Wang, Shihao et al., 2021). Since it can bring huge economic benefits to the planting area, it is widely cultivated worldwide, accounting for approximately 2.5% of the total arable land in the world (Wang et al., 2022; Zhang et al., 2021). Cotton fibers are the products from the cotton crop, whose growth includes four overlapping stages: initiation, cell elongation, secondary cell wall synthesis, and maturation (Song et al., 2020). It is comprised of cellulose, hemicellulose, pectin, wax, protein, ash, and so on. Among these components, cellulose is a leading ingredient in its secondary cell wall (Hao et al., 2017; Stana-Kleinschek and Ribitsch, 1998).
Cotton fiber, as a biomass fiber, has the advantages of excellent hygroscopicity (Wang, Shihao et al., 2021), biocompatibility (Sykam et al., 2021), air permeability (Haddar et al., 2014), renewability (Bergel et al., 2021), and biodegradability (Dissanayake et al., 2019). To obtain products with high added value, dyeing processes of cotton fibers are required. Reactive dyes are well known for their low price (Zhang et al., 2020), wide color range (Shu et al., 2018), and good colorfastness (Pei et al., 2021), making them the most widely applied dyes for dyeing of cotton fibers. However, conventional reactive dyeing of cotton consumes large amounts of water and inorganic salts, leading to the hydrolysis of reactive dyes during the dyeing process (Fernandez Cid et al., 2005). Therefore, the conventional reactive dyeing of cotton fibers may result in the discharge of dyeing effluents with high concentrations of unfixed dyes and inorganic salts (Dong et al., 2019).
To alleviate the above issues, many approaches have been proposed, including cationization of cotton fibers (Arivithamani and Giri Dev, 2017), supercritical carbon dioxide dyeing (Abou Elmaaty et al., 2022), foam dyeing (Chen et al., 2016), reversed micelle dyeing (Yi et al., 2012), solvent–water (H2O) dyeing (Fu et al., 2015; Liu et al., 2019), all-solvent dyeing (Chen, L. et al., 2015; Zhao et al., 2018), and other dyeing technologies (Han et al., 2022; Liyanapathiranage et al., 2020). Among these dyeing technologies, solvent–H2O dyeing of cotton is considered as a popular method for producing colored cotton products (Mu et al., 2019b). Fortunately, current technologies developed have yielded some promising results. For instance, dichloromethane–H2O system (Lim et al., 2001), soybean oil–H2O system (Mu et al., 2019a), cottonseed oil–H2O system (Mu et al., 2019b), spent cooking oil–H2O system (Liu et al., 2019), and decamethylcyclopentasiloxane–H2O system (Fu et al., 2015) were proposed for reducing hydrolysis of dyes and effluent discharges. Compared with the conventional aqueous dyeing method, these alternative dyeing technologies could realize high exhaustion and fixation of reactive dyes.
To reduce the inorganic salts and hydrolyzed dyes in the dyeing effluents, we exploited an ethanol (EtOH)–H2O mixture for eco-friendly dyeing of cotton fibers (Xia et al., 2021; Xia et al., 2018). Nevertheless, this method of producing colored cotton products may involve long dyeing time and high dyeing temperature. Therefore, we further developed an EtOH–carbon tetrachloride (CCl4)–H2O mixture to indicate the potential in realizing rapid, salt-free, and low-temperature production of colored cotton products (Wang et al., 2020). This dyeing approach can make full use of the investigated reactive dyes for achieving low discharge. However, since there are various of reactive dye chemistries, such as monochlorotriazine based reactive dye chemistry, dichlorotriazine based reactive dye chemistry, and vinyl sulphone based reactive dye chemistry, the dyeing process has to be validated for almost types of reactive dyes to meet the requirements of industrial production. Therefore, it is worth examining the relationship between the dye structure and dyeing properties of cotton in the developed EtOH–CCl4–H2O mixture. Considering that the developed solvent assisted dyeing technology is a promising approach for the cleaner production of cotton, when the dyeing performance of reactive dye in the ternary solvent system is comparable to or better than that in water system, the dye can be regarded as suitable for the solvent assisted dyeing method (Wang et al., 2020).
Herein, to provide insight on the adaptability of salt-free reactive dyeing for sustainable environmental development, the effect of dye chemistry on the dyeing property of cotton fibers in the proposed EtOH–CCl4–H2O ternary solvent system was investigated in detail. A range of commonly applied and representative reactive dyes were selected for the dyeing experiments according to their reactive groups, molecular weights, chromophores and sulfonate groups. The relative solubility, particle size distributions (PSDs) and transmission electron microscopy (TEM) images of the reactive dyes with various structures were tested accordingly. These dyes were used to dye cotton yarns in the conventional aqueous system and the developed EtOH–CCl4–H2O ternary solvent system. The K/S values, exhaustion, total fixation, and dyeing evenness of the dyed cotton samples in the absence of salt were estimated and compared with those conventional aqueous dyed samples. This study may provide a theoretical strategy for the industrial-scale production of cotton fibers using the developed solvent assisted dyeing technology.
2.1. Materials
Scoured and bleached cotton yarns (18.2 tex/2, two-fold yarn) were provided by Shandong Ruyi Technology Group Co. Ltd, China. Twelve commercially available reactive dyes include C.I. Reactive Blue 4 (RB4), C.I. Reactive Blue 19 (RB19), C.I. Reactive Blue 14 (RB14), C.I. Reactive Blue 63 (RB63), C.I. Reactive Yellow 3 (RY3), C.I. Reactive Red 195 (RR195), C.I. Reactive Blue 20 (RB20), C.I. Reactive Blue 171 (RB171), C.I. Reactive Blue 213 (RB213), C.I. Reactive Blue 222 (RB222), C.I. Reactive Blue 255 (RB255), and C.I. Reactive Blue 256 (RB256) were obtained from Sumitomo Chemical Co., Ltd, Tokyo, Japan. The details and chemical structures of these dyes are given in Table 1 and Fig. 1, respectively. Sodium sulfate (Na2SO4), sodium carbonate (Na2CO3), EtOH, and CCl4were of analytical grade and purchased from Sinopharm Chemical Reagent Co. Ltd., China.
|
Name of dyes |
Molecular formula |
Reactive group |
Molecular weight |
Chromophore |
Number of sulfonate groups |
|---|---|---|---|---|---|
|
RB4 |
C23H12Cl2N6Na2O8S2 |
Dichlorotriazine |
681.39 |
Anthraquinone |
2 |
|
RB19 |
C22H16N2Na2O11S3 |
Vinyl-sulfone |
626.55 |
Anthraquinone |
2 |
|
RB14 |
Monochlorotriazine |
CuPc |
2 |
||
|
RB63 |
Double monochlorotriazine |
CuPc |
5 |
||
|
RY3 |
C21H15ClN8Na2O7S2 |
Monochlorotriazine |
636.96 |
Monoazo |
2 |
|
RR195 |
C31H19ClN7Na5O19S6 |
Monochlorotriazine and vinyl-sulfone |
1136.32 |
Monoazo |
5 |
|
RB20 |
C20H16N3Na3O15S4 |
Vinyl-sulfone |
735.59 |
Monoazo and metal complexes |
3 |
|
RB171 |
C40H23Cl2N15Na6O19S6 |
Double monochlorotriazine |
1418.93 |
Double azo |
6 |
|
RB213 |
C27H15ClFN8Na5O16S5 |
Fluoro-chloro-methyl pyrimidine |
1037.18 |
Double azo |
5 |
|
RB222 |
C37H23ClN10Na6O22S7 |
Monochlorotriazine and vinyl-sulfone |
1357.49 |
Double azo |
6 |
|
RB255 |
C66H38Cl2N18Na10O34S10 |
Double monochlorotriazine |
2248.57 |
Quadruple azo |
10 |
|
RB256 |
C38H22Cl2N15Na5O17S5 |
Double monochlorotriazine |
1306.86 |
Double azo |
5 |
| CuPc: copper phthalocyanine. | |||||
2.2. Dyeing Procedures
All reactive dyeings were carried out using sealed stainless steel dyepots by an infrared dyeing machine (HIF-24, Huaxia Science & Technology Co. Ltd., China), at a dye concentration of 2% o.w.f., and a liquor to material ratio of 20:1.
The solvent assisted reactive dyeing of cotton was performed according to the optimal process as reported previously (Wang et al., 2020), the corresponding dyeing procedure are shown in Fig. 2. At the beginning, 2 g of cotton yarns were treated with a 15 g/L of Na2CO3 solution at 60°C for 10 min. The swollen samples were then padded to give 115 ± 5 wt % pickup. Next, the swollen yarns were dyed at 60°C for 60 min in a 55:40:5 (v/v) EtOH–CCl4–H2O system dyebath.
For comparison, the conventional reactive dyeing procedure of cotton with anthraquinone dyes and azo dyes was conducted using the method described in the literature (Wang et al., 2020). As for CuPc dyes, due to their inherent low exhaustion, their conventional reactive dyeing process adopts the following dyeing procedure. Initially, 2 g of cotton yarns were immersed in a CuPc dye aqueous solution at 60°C for 10 min. Then 50 g/L of Na2SO4 was added to the dye solution. After maintaining at the same temperature for another 40 min, 20 g/L of Na2CO3 was added to the dye bath. Finally, the dyeing temperature was enhanced to 80°C at a rate of 2°C/min and maintained at this temperature for 60 min.
After each dyeing step, the cotton sample was washed in a soaping solution for 10 min at 90°C and then, rinsed and dried.
2.3. Measurements
2.3.1. Dyeing assessment
The exhaustion (E) from dyeing liquor was determined using an UV-2700 UV–VIS spectrophotometer (Shimadzu Corporation, Japan) and calculated using Eq. (1) (Wang, Shengli et al., 2021).
1where A1 is the absorbance of the initial dyebath at λmax, A2 is the absorbance of the exhausted dyebath at λmax, n1 is the dilution multiple of the dyebath before the dyeing process, and n2 is the dilution multiple of the dyebath after the dyeing process.
The color strength (K/S value) at 20 random points on a single cotton sample were measured with a Color i7 computer color matching system (X-Rite, USA). In order to keep the samples flat, the dyed cotton yarn is tightly wound on a glass slide while keeping it neat.
The total fixation (T) of reactive dyes was calculated using Eq. (2) (Nallathambi and Venkateshwarapuram Rengaswami, 2016).
2where, the subscripts 0 and 1 show the values of the samples before and after soaping, respectively.
The leveling properties of the dyed cotton yarns were evaluated by the standard deviation (S) of the K/S values obtained from 20 random sample points.
2.3.2. Characterizations of dye liquor
To get the relative solubility (R), the absorbance values of the dye bath were measured at λmax on an UV–VIS spectrophotometer. The R was calculated according to Eq. (3).
(3)
where A0i represents the absorbance of the dyebath formed when the reactive dyes are added to water or EtOH or CCl4, A01 is the absorbance of the dyebath formed when the reactive dyes are added to water, n0i and n01 represent the dilution multiple of the corresponding dyebath, respectively.
The tests of PSD were carried out using a laser particle size analyzer (ZEN-3600, Malvern Instrument, UK).
The morphologies of the samples were measured by TEM (F200, JEOL, Japan) with an acceleration voltage of 200 kV.
2.3.3. Physicochemical characterizations of cotton
Fourier transform infrared (FTIR) spectra of undyed and dyed cotton samples were measured by the KBr disk method using a FTIR spectrometer (Nicolet iS50, Thermo Scientific, USA) in the range of 4000–400 cm− 1 (Xu et al., 2020).
Undyed and dyed cotton samples were subjected to X-ray diffraction (XRD) analysis with a X-ray diffractometer (Empyream, PANalytical, Netherlands). The XRD data of samples were recorded in a 2θ range of 5 º–60 º at a scanning rate of 5 º/min.
Thermogravimetric analysis (TGA) of various cotton samples was carried out on a thermogravimetric analyzer (TG209F1, Netzsch, Germany). Samples were heated from 30°C to 600°C at a heating rate of 10°C/min under nitrogen atmosphere.
3.1. Relative solubility of reactive dyes
The solubility of dyes has a significant influence on the aggregation of dye molecules, which greatly affects their adsorption and diffusion rates to the fibers (Wang et al., 2020; Xia et al., 2021; Xia et al., 2018). Twelve commercial reactive dyes were added to water, EtOH, and CCl4, respectively. The results were presented in Fig. 3. The investigated dyes were all soluble in water, and the resulting dye solutions were dark in color. This was because the molecules of these reactive dyes contain multiple water-soluble sulfonate groups. During the experiment, it was observed that two investigated anthraquinone reactive dyes are partially soluble in EtOH, while two CuPc reactive dyes and eight azo reactive dyes are slightly soluble or even insoluble in EtOH. This phenomenon may be ascribed to the fact that the molecules of RB4 and RB19 contain anthraquinone chromophores that can be dissolved in EtOH (Imran et al., 2018; Vázquez et al., 2015), while the molecules of CuPc dyes and azo dyes do not contain structures that can be dissolved in EtOH. For all the investigated reactive dyes, only undissolved dye particles remained in CCl4 even after 2 h of stirring, and the dye solutions appeared colorless, indicating that these reactive dyes were completely insoluble in CCl4. Poor solubility of the investigated dyes in EtOH or CCl4 may be attributed to the solubility parameter close principle.
To further study the dissolved states of the investigated reactive dyes in different dispersants, the relative solubility of twelve dyes in water, EtOH, and CCl4 were calculated. As can be seen from Table 2 and Fig. 3, the relative solubility values of these dyes in various dispersants are in accordance with their appearance.
|
Dyes |
Relative solubility (%) |
||
|---|---|---|---|
|
H2O |
EtOH |
CCl4 |
|
|
RB4 |
100 |
42.5 |
0 |
|
RB19 |
100 |
22.1 |
0 |
|
RB14 |
100 |
0.3 |
0 |
|
RB63 |
100 |
0.5 |
0 |
|
RY3 |
100 |
0.1 |
0 |
|
RR195 |
100 |
0.0 |
0 |
|
RB20 |
100 |
0.2 |
0 |
|
RB171 |
100 |
0.3 |
0 |
|
RB213 |
100 |
0.1 |
0 |
|
RB222 |
100 |
0.3 |
0 |
|
RB255 |
100 |
0.2 |
0 |
|
RB256 |
100 |
0.1 |
0 |
| a Dye concentration 1 g/L. | |||
3.2. PSDs and TEM images of reactive dyes
The curves of PSD for the investigated reactive dyes in the water system and EtOH–CCl4–H2O system are depicted in Fig. 4. It appears that, with the addition of 55 vol % EtOH and 40 vol % CCl4, the mean values of PSD of dyes shifts to visibly higher values, indicating that the visible aggregation of the investigated dyes was formed in the EtOH–CCl4–H2O mixture (Wang et al., 2020). This result may be explained by the fact that, as described in Section 3.1, the solubility of the investigated dyes in EtOH or CCl4 is lower than that in water. Specifically, the mean particle sizes of three types of reactive dyes, anthraquinone dyes, CuPc dyes, azo dyes, were in the order of anthraquinone dyes < azo dyes < CuPc dyes in the EtOH–CCl4–H2O mixture. This phenomenon may be caused by the following reasons. As mentioned in the previous section, for a 1 g/L dye solution, these dyes have similar relative solubility in water and CCl4. Therefore, the solubility of the investigated dyes in the EtOH–CCl4–H2O (55:40:5) mixture mainly depends on their relative solubility in EtOH. Since anthraquinone dyes are partially soluble in EtOH, while both CuPc dyes and azo dyes are slightly soluble or even insoluble in EtOH. As a result, in the EtOH–CCl4–H2O system, the average values of PSD of the investigated anthraquinone dyes were the smallest. As reported in the previous studies, CuPc molecules possess a planar structure (Chen et al., 2010; Chen, Y. et al., 2015; Kim et al., 2016). As a consequence, among dyes with three kinds of chromophores, CuPc reactive dyes had the best molecular coplanarity (Fig. 1 and Fig. 5). The resulting strongest dye-dye force existed between the CuPc dye molecules in the EtOH–CCl4–H2O mixture will cause the most severe π-π stacking or aggregation of the dye molecules themselves (Jiang et al., 2019; Jiang et al., 2018). Consequently, the investigated CuPc dyes displayed the largest mean particle sizes in the EtOH–CCl4–H2O mixture.
To verify the PSDs of the investigated reactive dyes assessed by a laser particle size analyzer, the morphologies of RB4, RB14, and RB20 in the water and EtOH–CCl4–H2O systems were observed in TEM observation. As depicted in Fig. 6A-F, the particle size of the investigated reactive dyes in the EtOH–CCl4–H2O mixture is larger than that in the water system, being consistent with the mean values of PSD displayed in Fig. 4.
3.3. Relationship between the molecular structure and coloration performances of reactive dyes
3.3.1. Reactive groups and dyeing properties relationship
To understand the influence of the reactive group categories of reactive dyes on the dyeing performances of cotton fibers using the solvent assisted dyeing method, five reactive dyes, RY3 (monochlorotriazine), RB20 (vinyl-sulfone), RB171 (double monochlorotriazine), RB213 (fluoro-chloro-methyl pyrimidine), and RB222 (monochlorotriazine and vinyl-sulfone), were used to dye cotton yarns in the EtOH–CCl4–H2O (55:40:5) mixture and their coloration properties were compared with the corresponding aqueous dyed samples. All these dyes are based on similar chromophores, but have different molecular weights and number of sulfonate groups. As shown in Table 3, cotton yarns dyed with these dyes using two dyeing systems displayed analogous and good dyeing properties, indicating that the applicability of the investigated reactive dyes in the EtOH–CCl4–H2O mixture appeared to be independent of their reactive groups.
Scheme of the dyeing process of anionic cotton yarn in the EtOH–CCl4–H2O ternary solvent system was described in Fig. 7A, which consisted of three stages: adsorption, diffusion and fixation. First, reactive dyes were adsorbed onto the the anionic cotton fiber surface. Nearly all the dyes in the EtOH–CCl4–H2O mixture could be absorbed on cotton fibers due to the high affinity of reactive dyes to cotton fibers, which made the dye molecules easy to discard the EtOH–CCl4–H2O mixture and spontaneously transfer to the surface of cotton fibers. Second, reactive dyes diffused into the interior of the anionic cotton fiber. After treating cotton yarns in the Na2CO3 aqueous solution, the dissociation of the cellulosic hydroxyl groups on the cotton fibers takes place, the anionic cellulosic nucleophile is generated (Fig. 7B). On the other hand, after the alkali pretreatment process, the swelling of cotton samples becomes better. Consequently, the pores of fibers were large, resulting in easy penetration of dye molecules into the inner part of fiber. Third, reactive dyes were fixed onto the anionic cotton fiber by the formation of a covalent bond between the reactive groups of reactive dyes with the hydroxyl groups of cotton fibers. For the monochlorotriazine based reactive dyes, the covalent bonding is formed with anionic cellulosic nucleophile by nucleophilic substitution (Fig. 7C) (Shu et al., 2019). For the vinyl-sulfone based reactive dyes, they form covalent bonding with an anionic cellulosic nucleophile by nucleophilic addition (Fig. 7D) (Nallathambi and Venkateshwarapuram Rengaswami, 2017). The reaction of reactive dyes with both monochlorotriazine group and vinyl-sulfone group on anionic cellulose nucleophile was carried out by nucleophile substitution and addition reaction (Fig. 7E) (Zhang et al., 2020).
|
Dyes |
Dyeing process |
K/S |
E (%) |
T (%) |
|---|---|---|---|---|
|
RB4 |
Aqueous |
4.24 |
76.10 |
39.12 |
|
Solvent |
1.77 |
4.00 |
2.23 |
|
|
RB19 |
Aqueous |
8.85 |
93.75 |
77.55 |
|
Solvent |
2.36 |
14.02 |
13.51 |
|
|
RB14 |
Aqueous |
1.39 |
20.00 |
13.25 |
|
Solvent |
2.81 |
99.44 |
44.60 |
|
|
RB63 |
Aqueous |
7.14 |
21.65 |
9.56 |
|
Solvent |
10.71 |
99.48 |
46.45 |
|
|
RY3 |
Aqueous |
9.87 |
68.60 |
63.08 |
|
Solvent |
11.20 |
98.85 |
69.36 |
|
|
RR195 |
Aqueous |
8.76 |
82.87 |
77.63 |
|
Solvent |
10.63 |
98.57 |
87.53 |
|
|
RB20 |
Aqueous |
17.16 |
90.10 |
88.50 |
|
Solvent |
20.87 |
94.19 |
89.67 |
|
|
RB171 |
Aqueous |
10.53 |
83.68 |
77.34 |
|
Solvent |
13.32 |
99.68 |
87.42 |
|
|
RB213 |
Aqueous |
3.94 |
85.69 |
65.10 |
|
Solvent |
5.14 |
98.30 |
70.64 |
|
|
RB222 |
Aqueous |
11.63 |
78.62 |
72.09 |
|
Solvent |
15.52 |
99.35 |
81.76 |
|
|
RB255 |
Aqueous |
10.41 |
88.75 |
69.40 |
|
Solvent |
12.20 |
99.70 |
77.50 |
|
|
RB256 |
Aqueous |
9.55 |
76.79 |
61.35 |
|
Solvent |
12.95 |
99.78 |
73.31 |
3.3.2. Molecular weights and dyeing properties relationship
The dyeing properties of the conventional water and solvent assisted dyeing processes were compared based on the K/S values, exhaustion, and total fixation of reactive dyes with different molecular weights–RY3 (636.96), RB20 (735.59), RR195 (1136.32), and RB222 (1357.49), as displayed in Table 3. It can be seen that molecular weights of the investigated reactive dyes seem to have little influence on their suitability in the solvent assisted dyeing method. Therefore, it is technically feasible to color cotton fibers in the EtOH–CCl4–H2O mixture using these reactive dyes.
3.3.3. Chromophores and dyeing properties relationship
Cotton samples were dyed with anthraquinone dyes (RB4 and RB19), CuPc dyes (RB14 and RB63), and azo dyes (RY3 and RB20) using conventional water system and ternary solvent system to pick out the suitable reactive dyes for cotton dyeing in EtOH–CCl4–H2O (55:40:5) mixture. As presented in Table 3, the K/S values, exhaustion, and total fixation of cotton yarns dyed with anthraquinone dyes in the ternary solvent system were lower than those in the water system. For CuPc dyes and azo dyes, all the solvent-assisted dyed cotton yarns exhibited higher K/S values, exhaustion, and total fixation than those samples dyed in the conventional aqueous dyeing system, which implies that the investigated CuPc dyes and azo dyes are suitable for dyeing cotton samples in the EtOH–CCl4–H2O mixture. The following aspects may contribute to these results. In the EtOH–CCl4–H2O mixture dyeing process, one of the most important reasons why reactive dyes can obtain better dyeing properties than in water system is that these reactive dyes are soluble only in water, but not in EtOH or CCl4, thereby they tend to form obvious aggregation in ternary solvent system (Wang et al., 2020). The resulting large dye concentration difference formed between the EtOH–CCl4–H2O system dye solution and the fibers surface may contribute to the rapid adsorption of dye molecules onto cotton fibers, and then quickly penetrate into the cotton fibers due to the good wettability of the EtOH–CCl4–H2O mixture, giving rise to excellent dyeing properties of cotton fibers. Among the three types of reactive dyes, CuPc dyes and azo dyes are soluble only in the very small amount of water contained in the EtOH–CCl4–H2O (55:40:5) system, hence the dyeing performances of these dyes in ternary solvent system are better than those in the water system. Since the investigated anthraquinone dyes are partially soluble in EtOH (Fig. 3 and Table 2), for this type of dyes, the dye concentration difference formed between the EtOH–CCl4–H2O mixture and the fibers surface are significantly lower than those for CuPc dyes and azo dyes. Besides, these anthraquinone dyes have relatively smaller molecular sizes (Fig. 1). The resulting lower affinity between the cotton fibers and the dye molecules may result in the deteriorative K/S values, exhaustion, and total fixation of the investigated anthraquinone dyes in solvent assisted dyeing method than in water system. In the EtOH–CCl4–H2O (55:40:5) mixture, the mean particle size of CuPc dyes is larger than those of azo dyes and anthraquinone dyes (Fig. 4), which may result in the formation of maximum affinity between cotton fibers and the CuPc dyes. As a result, the exhaustion of the investigated CuPc dyes was the largest. The large size and good molecular coplanarity of dye molecules are beneficial to the adsorption of dye molecules onto cotton fibers (Jiang et al., 2019; Xia et al., 2018). However, excess molecular coplanarity may, in turn, prevent dye molecules from permeating into the cotton fibers. Therefore, the total fixation of samples dyed with the investigated CuPc dyes in the solvent-assisted dyeing method is worse than those with azo dyes. It can be seen from the above results that the chromophores of reactive dyes may play a crucial role in their suitability in EtOH–CCl4–H2O mixture.
3.3.4. Number of sulfonate groups and dyeing properties relationship
To determine the effect of the number of sulfonate groups of reactive dyes on their applicability in the EtOH–CCl4–H2O mixture, three reactive dyes having the same reactive group and similar chromophores, RB171 (6), RB255 (10), and RB256 (5), were selected for dyeing cotton in water and EtOH–CCl4–H2O (55:40:5) systems. As depicted in Table 3, these reactive dyes differ in the number of sulfonate groups but show higher K/S values, exhaustion, and total fixation in the ternary solvent system than those in the water system, suggesting that the number of sulfonate groups of the investigated reactive dyes may not be a significant determinant of their suitability for the solvent-assisted dyeing method.
3.4. Levelling properties of reactive dyes
The standard deviation (S) of K/S values were used to evaluate the dyeing levelness of cotton samples dyed in the water and EtOH–CCl4–H2O systems and the results were exhibited in Fig. 8. It was obvious that the S values of both the solvent-assisted dyed and aqueous dyed cotton samples showed similarly low values for the investigated dyes, indicating that the dyed cotton samples obtained good levelling properties. The digital photographs of cotton yarns dyed with various reactive dyes are also presented in Fig. 8. The pictures further confirmed that the acquisition of good evenness in the aqueous dyed and solvent-assisted dyed cotton yarns.
3.5. Effect of dyeing method on physicochemical properties of cotton fibers
To well understand the effect of dyeing approach on the chemical compositions of cotton, FTIR analysis of various cotton samples was performed and the results were represented in Fig. 9A. It can be seen that all samples showed characteristic peaks of cellulose at 3275 cm-1 (O–H stretching), 2898 cm-1 (C–H stretching), 1647 cm-1 (C = O stretching), 1431 cm-1 (C–H bending), 1369 cm-1 (C–H stretching), 1115 cm-1 (C–O stretching), and 899 cm-1 (C–O stretching) (Fu et al., 2020; Huang et al., 2022; Penthala et al., 2022; Zambrano et al., 2021). These results indicated that the chemical structure of cellulose did not change significantly after the dyeing process.
XRD patterns of the undyed and dyed cotton samples were shown in Fig. 9B. The three cotton samples all exhibited typical diffraction peaks of cellulose existed at 2θ = 15.2°, 16.9°, and 23.3°, assigned to the (1–10), (110), and (200) planes, respectively (Zhao et al., 2020). According to Segal’s equation, the calculated crystallinity of contral sample, aqueous dyed sample and solvent-assisted dyed sample were 75.8%,77.2%, and 73.4%, respectively, which were in accordance with previous report (Lin et al., 2021; Xia et al., 2021). It can be concluded that the developed solvent-assisted dyeing method did not affect the crystalline form and crystallinity of cotton fiber.
The TGA curves of different cotton samples were completed to compare the thermostability of the aqueous dyed sample, solvent-assisted dyed sample and the original sample. As displayed in Fig. 9C, the pyrolysis trends of aqueous dyed cotton and solvent-assisted dyed cotton were similar to each other, indicating that these cellulose samples have similar thermal stability. The thermal degradation of both cotton samples includes three stages: moisture loss, decomposition of cellulose, and char pyrolysis (He et al., 2014). TGA analysis revealed that the dyeing approach had no significant effect on the thermal properties of the samples.
3.6. Material consumption
The materials consumed to dye 1 ton of cotton yarns using the conventional aqueous and solvent assisted dyeing methods are listed in Table 4. Compared with the conventional dyeing approach, dyeing 1 ton of cotton samples with solvent assisted dyeing process needs 11000 L of EtOH and 8000 L of CCl4. Fortunately, as organic solvents widely used in industry, the recycling technologies of EtOH and CCl4 are relatively mature, and most of the EtOH and CCl4 in the dyeing effluents could be recycled after solvent assisted dyeing process (Wang et al., 2020). Consequently, the actual consumption of EtOH and CCl4 during each dyeing cycle is small. In view of the fact that EtOH and CCl4 are very volatile, all the experiments including alkali treatment, dyeing, and soaping, were performed under sealed conditions in this study. Therefore, EtOH or CCl4 will not be directly released into the surrounding environment. In addition, the Na2SO4 and water in ternary solvent dyeing system were saved by 800 kg and 19000 L, respectively, due to the addition of EtOH and CCl4. In other words, the developed solvent assisted dyeing method reduces the amount of wastewater and the concentration of inorganic salts, which contributes to environmental protection. The results indicate that solvent assisted dyeing is a promising cleaner production technology for cotton dyeing.
|
Dyeing media |
||
|---|---|---|
|
Aqueous |
Solvent |
|
|
Dye (kg) |
20 |
20 |
|
Na2SO4 (kg) |
800 |
0 |
|
Na2CO3 (kg) |
300 |
300 |
|
Water (L) |
20000 |
1000 |
|
EtOH (L) |
0 |
11000 |
|
CCl4 (L) |
0 |
8000 |
| a The dye concentration is 2% o.w.f., liquor to material ratio is 20:1. | ||
In summary, twelve commercial reactive dyes with different reactive groups, molecular weights, chromophores, and the number of sulfonate groups, were selected as representative dyes and used to dye cotton yarns. As expected, these dyes are soluble in water but not in CCl4. CuPc dyes and azo dyes are slightly soluble or even insoluble in EtOH. Anthraquinone dyes, however, are partially soluble in EtOH. Thus, in the EtOH–CCl4–H2O (55:40:5) mixture, the particle sizes of the investigated anthraquinone dyes are distributed over significantly smaller ranges than those of CuPc dyes and azo dyes. Interestingly, differences in reactive groups, molecular weights, and number of sulfonate groups between the investigated dyes have no obvious influence on their applicability in the EtOH–CCl4–H2O mixture. The relationship between the chromophores and coloration performances of reactive dyes revealed that the different chromophores made the evident difference. Cotton yarns dyed with anthraquinone dyes in a ternary solvent system displayed deteriorative dyeing performances than those in the water system, whereas samples dyed with CuPc dyes and azo dyes using the solvent assisted dyeing method obtained better dyeing properties compared to the conventional approach. Both the conventional aqueous dyed and solvent-assisted dyed cotton yarns exhibited satisfactory leveling properties, indicating that the investigated CuPc dyes and azo dyes are suitable for dyeing cotton samples in the EtOH–CCl4–H2O mixture. This study may provide a theoretical strategy for the industrial-scale production of cotton fibers using the developed solvent assisted dyeing technology. The reuse of the organic solvents in the EtOH–CCl4–H2O mixture should be investigated in the future work.
Ethics approval and consent to participate
Not applicable
Consent for publication
All the authors gave consent for publication.
Availability of data and materials
Data and materials will be made available on request.
Declaration of competing interest
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.
Funding
This work was supported by the National Natural Science Foundation of China (U21A2095), National Natural Science Foundation of China (21905214), Local Science and Technology Development Projects Guided by the Central Government (2020ZYYD038), and Opening Project of State Key Laboratory of Silkworm Genome Biology, Ministry of Agriculture, Southwest University (sklsgb-2019KF08).
CRediT authorship contribution statement
Aming Wang: Methodology, Validation, Formal analysis, Investigation, Writing - original draft, Visualization. Dan Sheng: Conceptualization, Validation, Supervision. Chunhua Zhang: Conceptualization, Data curation, Supervision, Funding acquisition. Junyao Gong: Data curation, Visualization. Zhuan Fu: Validation, Visualization. Yunli Wang: Conceptualization, Methodology, Supervision. Wenbin Li: Conceptualization, Project administration, Funding acquisition. Liangjun Xia: Conceptualization, Methodology, Supervision, Data Curation, Writing - review & editing, Supervision. Weilin Xu: Conceptualization, Methodology, Resources, Supervision, Funding acquisition.
Acknowledgments
We thank National Natural Science Foundation of China (U21A2095), National Natural Science Foundation of China (21905214), Local Science and Technology Development Projects Guided by the Central Government (2020ZYYD038), and Opening Project of State Key Laboratory of Silkworm Genome Biology, Ministry of Agriculture, Southwest University (sklsgb-2019KF08).
- Abou Elmaaty, T., Elsisi, H., Negm, E., Ayad, S., Sofan, M., 2022. Novel nano silica assisted synthesis of azo pyrazole for the sustainable dyeing and antimicrobial finishing of cotton fabrics in supercritical carbon dioxide. The Journal of Supercritical Fluids 179, 105354.
- Arivithamani, N., Giri Dev, V.R., 2017. Sustainable bulk scale cationization of cotton hosiery fabrics for salt-free reactive dyeing process. Journal of Cleaner Production 149, 1188-1199.
- Bergel, B.F., Araujo, L.L., Santana, R.M.C., 2021. Effects of the addition of cotton fibers and cotton microfibers on the structure and mechanical properties of starch foams made from potato starch. Carbohydrate Polymer Technologies and Applications 2, 100167.
- Cai, G., Xu, Z., Yang, M., Tang, B., Wang, X., 2017. Functionalization of cotton fabrics through thermal reduction of graphene oxide. Applied Surface Science 393, 441-448.
- Chen, L., Wang, B., Chen, J., Ruan, X., Yang, Y., 2015. Comprehensive study on cellulose swelling for completely recyclable nonaqueous reactive dyeing. Industrial & Engineering Chemistry Research 54(9), 2439-2446.
- Chen, S., Zhang, W., Wang, C., Sun, S., 2016. A recycled foam coloring approach based on the reversible photo-isomerization of an azobenzene cationic surfactant. Green Chemistry 18(14), 3972-3980.
- Chen, W.-H., Ko, W.-Y., Chen, Y.-S., Cheng, C.-Y., Chan, C.-M., Lin, K.-J., 2010. Growth of copper phthalocyanine rods on Au plasmon electrodes through micelle disruption methods. Langmuir 26(4), 2191-2195.
- Chen, Y., Cao, W., Wang, K., Jiang, J., 2015. Unprecedented phthalocyanines bearing eight di-butylamino peripheral substituents: synthesis, spectroscopy, and structure. Inorganic Chemistry 54(20), 9962-9967.
- Dissanayake, N., Thalangamaarachchige, V.D., Thakurathi, M., Knight, M., Quitevis, E.L., Abidi, N., 2019. Dissolution of cotton cellulose in 1:1 mixtures of 1-butyl-3-methylimidazolium methylphosphonate and 1-alkylimidazole co-solvents. Carbohydrate Polymers 221, 63-72.
- Dong, X., Gu, Z., Hang, C., Ke, G., Jiang, L., He, J., 2019. Study on the salt-free low-alkaline reactive cotton dyeing in high concentration of ethanol in volume. Journal of Cleaner Production 226, 316-323.
- Fernandez Cid, M.V., van Spronsen, J., van der Kraan, M., Veugelers, W.J.T., Woerlee, G.F., Witkamp, G.J., 2005. Excellent dye fixation on cotton dyed in supercritical carbon dioxide using fluorotriazine reactive dyes. Green Chemistry 7(8), 609-616.
- Fu, C., Wang, J., Shao, J., Pu, D., Chen, J., Liu, J., 2015. A non-aqueous dyeing process of reactive dye on cotton. The Journal of The Textile Institute 106(2), 152-161.
- Fu, Z., Zhou, S., Xia, L., Mao, Y., Zhu, L., Cheng, Y., Wang, A., Zhang, C., Xu, W., 2020. Juncus effusus fiber-based cellulose cigarette filter with 3D hierarchically porous structure for removal of PAHs from mainstream smoke. Carbohydrate Polymers 241, 116308.
- Haddar, W., Elksibi, I., Meksi, N., Mhenni, M.F., 2014. Valorization of the leaves of fennel (Foeniculum vulgare) as natural dyes fixed on modified cotton: A dyeing process optimization based on a response surface methodology. Industrial Crops and Products 52, 588-596.
- Han, L., Ren, Y., Fang, K., Zhang, K., Zhang, Y., Wang, W., Zhang, Z., Xie, R., 2022. Short clean dyeing of two-component cotton/polyamide fabrics through adaptive adjustment of the dye solution. Journal of Cleaner Production 333, 130077.
- Hao, L., Wang, R., Fang, K., Cai, Y., 2017. The modification of cotton substrate using chitosan for improving its dyeability towards anionic microencapsulated nano-pigment particles. Industrial Crops and Products 95, 348-356.
- He, X., Tao, R., Zhou, T., Wang, C., Xie, K., 2014. Structure and properties of cotton fabrics treated with functionalized dialdehyde chitosan. Carbohydrate Polymers 103, 558-565.
- Huang, C., Yu, H., Abdalkarim, S.Y.H., Li, Y., Chen, X., Yang, X., Zhou, Y., Zhang, L., 2022. A comprehensive investigation on cellulose nanocrystals with different crystal structures from cotton via an efficient route. Carbohydrate Polymers 276, 118766.
- Imran, S., Hossain, A., Parui, S., Sengupta, P.S., Roy, S., Guin, P.S., 2018. Effect of electrolytes on the solubility and solution thermodynamics of 1-amino-4-hydroxy-9,10-anthraquinone, an analogue of anthracycline anticancer drugs, in aqueous ethanol media using theoretical and UV–Vis spectroscopic study. Journal of Molecular Liquids 252, 151-157.
- Jiang, H., Hu, Q., Cai, J., Cui, Z., Zheng, J., Chen, W., 2019. Synthesis and dyeing properties of indophenine dyes for polyester fabrics. Dyes and Pigments 166, 130-139.
- Jiang, H., Zhang, L., Cai, J., Ren, J., Cui, Z., Chen, W., 2018. Quinoidal bithiophene as disperse dye: Substituent effect on dyeing performance. Dyes and Pigments 151, 363-371.
- Kim, H.-S., Muthukumar, P., Ku, K.-S., Son, Y.-A., 2016. Synthesis and characterization of water-soluble phthalocyanine Copper(II) complex and its coloration on acrylic fibers. Fibers and Polymers 16(12), 2552-2557.
- Lim, Y.-J., Kim, T.-K., Cho, K.-H., 2001. Reactive dyeing of cotton in water-organic solvent mixture. Sen'i Gakkaishi 57(1), 21-24.
- Lin, C., Chen, B., Liu, Y., Chen, Y., Liu, M., Zhu, J.Y., 2021. Carboxylated cellulose nanocrystals with chiral nematic property from cotton by dicarboxylic acid hydrolysis. Carbohydrate Polymers 264, 118039.
- Liu, L., Mu, B., Li, W., Yang, Y., 2019. Semistable emulsion system based on spent cooking oil for pilot-scale reactive dyeing with minimal discharges. ACS Sustainable Chemistry & Engineering 7(16), 13698-13707.
- Liyanapathiranage, A., Peña, M.J., Sharma, S., Minko, S., 2020. Nanocellulose-Based Sustainable Dyeing of Cotton Textiles with Minimized Water Pollution. ACS Omega 5(16), 9196-9203.
- Mu, B., Liu, L., Li, W., Yang, Y., 2019a. High sorption of reactive dyes onto cotton controlled by chemical potential gradient for reduction of dyeing effluents. Journal of Environmental Management 239, 271-278.
- Mu, B., Liu, L., Li, W., Yang, Y., 2019b. A water/cottonseed oil bath with controllable dye sorption for high dyeing quality and minimum discharges. Journal of Cleaner Production 236, 117566.
- Nallathambi, A., Venkateshwarapuram Rengaswami, G.D., 2016. Salt-free reactive dyeing of cotton hosiery fabrics by exhaust application of cationic agent. Carbohydrate Polymers 152, 1-11.
- Nallathambi, A., Venkateshwarapuram Rengaswami, G.D., 2017. Industrial scale salt-free reactive dyeing of cationized cotton fabric with different reactive dye chemistry. Carbohydrate Polymers 174, 137-145.
- Pei, L., Luo, Y., Saleem, M.A., Wang, J., 2021. Sustainable pilot scale reactive dyeing based on silicone oil for improving dye fixation and reducing discharges. Journal of Cleaner Production 279, 123831.
- Penthala, R., Oh, H., Park, S.H., Lee, I.Y., Ko, E.H., Son, Y.-A., 2022. Synthesis of novel reactive disperse dyes comprising carbamate and cyanuric chloride groups for dyeing polyamide and cotton fabrics in supercritical carbon dioxide. Dyes and Pigments 198, 110003.
- Shu, D., Fang, K., Liu, X., Cai, Y., An, F., Qu, G., Liang, Y., 2019. Cleaner pad-steam dyeing technology for cotton fabrics with excellent utilization of reactive dye. Journal of Cleaner Production 241, 118370.
- Shu, D., Fang, K., Liu, X., Cai, Y., Zhang, X., Zhang, J., 2018. Cleaner coloration of cotton fabric with reactive dyes using a pad-batch-steam dyeing process. Journal of Cleaner Production 196, 935-942.
- Song, Z., Chen, Y., Zhang, C., Zhang, J., Huo, X., Gao, Y., Pan, A., Du, Z., Zhou, J., Zhao, Y., Liu, Z., Wang, F., Zhang, J., 2020. RNA-seq reveals hormone-regulated synthesis of non-cellulose polysaccharides associated with fiber strength in a single-chromosomal-fragment-substituted upland cotton line. The Crop Journal 8(2), 273-286.
- Stana-Kleinschek, K., Ribitsch, V., 1998. Electrokinetic properties of processed cellulose fibers. Colloids and Surfaces A: Physicochemical and Engineering Aspects 140(1), 127-138.
- Sykam, K., Försth, M., Sas, G., Restás, Á., Das, O., 2021. Phytic acid: A bio-based flame retardant for cotton and wool fabrics. Industrial Crops and Products 164, 113349.
- Vázquez, M.F.B., Comini, L.R., Martini, R.E., Montoya, S.C.N., Bottini, S., Cabrera, J.L., 2015. Ultrasonic-assisted extraction of anthraquinones from Heterophyllaea pustulata Hook f. (Rubiaceae) using ethanol–water mixtures. Industrial Crops and Products 69, 278-283.
- Wang, A., Xia, L., Zhou, S., Guo, H., Wang, Y., Xu, W., 2020. Solvent assisted reactive dyeing of cotton with high exhaustion in the absence of salt. Journal of Cleaner Production 267, 122062.
- Wang, J., Zhang, Z., Gong, Z., Liang, Y., Ai, X., Sang, Z., Guo, J., Li, X., Zheng, J., 2022. Analysis of the genetic structure and diversity of upland cotton groups in different planting areas based on SNP markers. Gene 809, 146042.
- Wang, S., Gao, L., Hou, A., Xie, K., Song, X., 2021. Design, synthesis of novel bisazo disperse dyes: Structure analysis and dyeing performance on PET. Dyes and Pigments 196, 109761.
- Wang, S., Sun, L., Li, Y., Wang, H., Liu, J., Zhu, P., Dong, C., 2021. Properties of flame-retardant cotton fabrics: Combustion behavior, thermal stability and mechanism of Si/P/N synergistic effect. Industrial Crops and Products 173, 114157.
- Xia, L., Wang, A., Wang, Y., Zhang, C., Wang, Y., Zhou, S., Fu, Z., Zhao, H., Ding, C., Xu, W., 2021. Eco-friendly dyeing of raw cotton fibres in an ethanol–water mixture without scouring and bleaching pretreatments. Green Chemistry 23(2), 796-807.
- Xia, L., Wang, A., Zhang, C., Liu, Y., Guo, H., Ding, C., Wang, Y., Xu, W., 2018. Environmentally friendly dyeing of cotton in an ethanol–water mixture with excellent exhaustion. Green Chemistry 20(19), 4473-4483.
- Xu, X., Gong, J., Li, Z., Li, Q., Zhang, J., Wang, L., Huang, J., 2020. Mordant Free Dyeing and Functionalization of Wool Fabrics with Biocolorants Derived from Apocynum venetum L. Bast. ACS Sustainable Chemistry & Engineering 8(33), 12686-12695.
- Yi, S., Dong, Y., Li, B., Ding, Z., Huang, X., Xue, L., 2012. Adsorption and fixation behaviour of CI Reactive Red 195 on cotton woven fabric in a nonionic surfactant Triton X-100 reverse micelle. Coloration Technology 128(4), 306-314.
- Zambrano, M.C., Pawlak, J.J., Daystar, J., Ankeny, M., Venditti, R.A., 2021. Impact of dyes and finishes on the aquatic biodegradability of cotton textile fibers and microfibers released on laundering clothes: Correlations between enzyme adsorption and activity and biodegradation rates. Marine Pollution Bulletin 165, 112030.
- Zhang, H., Wang, J., Xie, K., Pei, L., Hou, A., 2020. Synthesis of novel green reactive dyes and relationship between their structures and printing properties. Dyes and Pigments 174, 108079.
- Zhang, Z., Chattha, M.S., Ahmed, S., Liu, J., Liu, A., Yang, L., Lv, N., Ma, X., Li, X.e., Hao, F., Yang, G., 2021. Nitrogen reduction in high plant density cotton is feasible due to quicker biomass accumulation. Industrial Crops and Products 172, 114070.
- Zhao, J., Agaba, A., Sui, X., Mao, Z., Xu, H., Zhong, Y., Zhang, L., Wang, B., 2018. A heterogeneous binary solvent system for recyclable reactive dyeing of cotton fabrics. Cellulose 25(12), 7381-7392.
- Zhao, J., Chen, J., Chen, Z., Zhang, Y., Xia, D., Wang, Q., 2020. Flexible cotton fabrics/PDA/BiOBr composite photocatalyst using bioinspired polydopamine as electron transfer mediators for dye degradation and Cr(VI) reduction under visible light. Colloids and Surfaces A: Physicochemical and Engineering Aspects 593, 124623.
No competing interests reported.