Salt-free dyeability of thiourea grafted cotton fabric

In this study salt-free dyeing cotton fabric was achieved by grafting thiourea to cotton fibers, where the thiourea grafted cotton fabric (TUGCF) was prepared by epoxidizing cotton fibers with epichlorohydrin in water and subsequently grafting in aqueous solution of thiourea. Fourier transform infrared spectra (FTIR) and XPS of the TUGCF indicated that a great amount of epoxy groups from the epoxidized cotton fibers reacted with amino groups from thiourea. The TUGCF fabric prepared at the optimum condition and subsequently dyed with reactive dyes in the absence of salt displayed significantly enhanced color strength, showing better dyeing properties when compared with the untreated cotton fabric dyed with conventional methods, in terms of washing fastness, rubbing fastness, and levelness. It was found that the dyeing performance of Reactive Red B-3BF followed a Langmuir-type adsorption curve when used to salt-free dye the TUGCF.     

Adsorption and dyeing characteristics of reactive dyes onto cotton fiber in nonionic Triton X-100 reverse micelles

The nonionic reverse micelles used for dyeing cotton fiber were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of reactive dye aqueous solution. The adsorption capacity of three water-soluble anionic azo dyes including Reactive Blue 222, Reactive Red 195 and Reactive Yellow 145 onto cotton fiber was investigated. The Langmuir and Freundlich isothermals were employed to model the adsorption data. In addition, the color strength and fixation rate of cotton fabrics dyed in the reverse micelles and bulk water were examined and compared. The salt and alkali as influencing factors were also discussed. The FT-IR spectra were employed to study the polarity of water added in reverse micelles. The results indicated that the adsorption of the dyes onto cotton showed better agreement with Langmuir model. The adsorption process was monolayer adsorption. Reactive Yellow 145 with lower negative charge and higher hydrophilicity exhibited the higher adsorption capacity. The fixation percentage and color strength of the cotton fiber dyed in TX-100 reverse micelles was higher than those in bulk water. The polarity of water in TX-100 reverse micelles was lower than that in bulk water.     

Dyeing characteristics of Nylon,cotton and N/C mixture fabrics with reactive-disperse dyes containing a sulphatoethylsulphone group

The dyeing and color fastness properties of three reactive-disperse dyes containing a sulphatoethylsulphone group on Nylon, cotton and N/C mixture fabrics were examined. Reduction-clearing was more effective in removing the unfixed dyes than soaping since the reactive-disperse dye became hydrophobic during dyeing process. Nylon was dyed well with three reactive-disperse dyes at pH 5∼8 and difference in chemical structure between dyes did not affect the final color strength of the dyed Nylon fiber, but their build-up properties on Nylon were not so good. The color strength of the dyed cotton was not as high as that of Nylon. The color strength of cotton increased by lowering dyeing temperature when the reactive-disperse dyes having hydroxy group were used. Nylon absorbed more dye molecules than cotton in simultaneous dyeing, the color difference between Nylon and cotton could be reduced as the dyeing temperature decreased. N/C mixture fabric was dyed well at 60 °C with the reactive-disperse dyes having hydroxyl group when applied at pH 7 and 60 °C, and their build-up properties were good. It was also found that washing fastness and rubbing fastness of dyed Nylon, cotton and N/C fabrics with the reactive-disperse dyes were excellent, while light fastness was moderate.     

Investigation of stain-resistant cationic dyeable nylon 6 modified with sodium salt of 5-sulfoisophthalic acid and polyethylene glycol

Nylon 6 can be dyed with acid dyes and therefore it can also be stained by natural or artificial acid dyes existing in some foods and drinks when they are spilled on nylon fabrics. In this study, cationic dyeable polyamide (CD-PA6) was synthesized with sodium salt from 5-sulfoisophthalic acid (5-SSIPA) and easily cationic dyeable polyamide (ECD-PA6) was prepared with 5-SSIAP and polyethylene glycol (PEG). The influence of the chemical modification to CD-PA6 and ECD-PA6 on the resultant structures were characterized by wide angle X-ray diffraction (WAXD) and Fourier transform infrared spectroscopy (FT-IR), and their thermal properties were tested by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The effects of varying 5-SSIPA content on the cationic dye uptake and acid dye resistance rate were also investigated, as well as mechanical properties of the modified PA6. Incorporating PEG not only destroyed the regularity of molecular chain arrangement and created more amorphous regions in the ECD-PA6 samples, but also changed the nylon 6 from α-form to γ-form. Results revealed a considerable improvement in cationic dye uptake and acid dye resistance rate in the modified fibers compared with unmodified fibers.     

Preparation of adsorbent based on cotton fiber for removal of dyes

Synthetic dyes are used extensively in modern industries, which are toxic and harmful to environment and human. Cotton fiber is a kind of abundant, renewable and eco-friendly cellulose fiber in nature, however, the adsorption capacity of raw cellulose for pollutants was often low. Therefore, an efficient adsorbent for removal of dyes was successfully prepared by grafting beta-cyclodextrin (β-CD) and amino-terminated hyperbranched polymer (NH₂-HBP) onto cotton fibers in this study, which was effective to anionic dyes and cationic dyes. The adsorbent were characterized using FTIR, SEM and XPS analysis. The results of adsorption experiments showed that the adsorbent based on cotton fiber exhibited better adsorption performance for Congo red(CR) and methylene blue(MB). The experimental results revealed that the pH value had a great influence on the adsorption capacity.     

Efficient separation and reuse of CI Reactive Blue 19 from dyeing effluent by solvent extraction

In order to reduce environmental pollution from dyeing effluent, the cationic reverse micelles were prepared and used for removal of anionic Color Index (CI) Reactive Blue 19. The effect of surfactants, dyes, temperature and ultrasonic treatment on dye removal was investigated, respectively. The conductivity of CI Reactive Blue 19 aqueous solution was measured during removal process. In addition, the photograph of CI Reactive Blue 19 was also obtained. Finally, the removed dyes were backward extracted and reused for dyeing cotton fabrics. The results indicated that the removal of dyes was increased with increasing surfactants concentration and temperature, while the dye concentration exhibited the reverse trend. The higher removal of dyes could be caused by using ultrasonic treatment. The conductivity of dye aqueous solution was decreased with increasing surfactant concentration for the removal of dyes. The CI Reactive Blue 19 from backward extraction was reused for dyeing cotton fabrics, which exhibited the good property.     

Study of analytical methods for quantifying unfixed form of bifunctional reactive dyes used in dyeing cellulosic fibers (cotton)

The objective of the present study was to examine the reliability and compatibility of three methods for quantifying the unfixed form of heterobifunctional reactive dye type monochlorotriazine/β-sulfatoethylsulfone used in dyeing cellulosic fibers (cotton). The first method is based on spectrophotometric analysis by measuring the absorbance of residual dyebath (after dyeing process) and residual soaping bath (after washing-off phase), the second one is based on colorimetric analysis by measuring the reflectance of dyed fabric, and the third on high-performance liquid chromatography (HPLC) technique. The purpose of the latter is to identify and quantify the hydrolyzed and inactive forms of dye in residual soaping bath. The calculated unfixed dye rates unequivocally prove the reliability and compatibility of these methods. According to the availability of the required laboratory instruments, we can select the most suitable method in every case, though the tests proved that the HPLC technique is most efficient.     

High Light-Fastness Acid Dyes Synthesized from Corresponding Anthraquinone Chromophore Utilizing a Sulfonation Reaction. I. Dye Synthesis and Characterization

As the diameter of polyamide fibers decreased to finer denier, the dyeing fastness tends to be deteriorated due to the increase of their surface area, particularly both light fastness and wash fastness. In this study, three acid dyes were synthesized utilizing a sulfonation reaction starting from corresponding hydrophobic dye (for yellow and red dye) and dye intermediate containing a sulfonic acid group (for blue dye), those featured by high light fastness property. A Gaussian structural prediction model was used to determine the structure of the acid dyes prior to dye synthesis, and the optimal structures of three acid dyes were analyzed. Dye structures prepared were confirmed by ¹H-NMR, mass spectroscopy, and elemental analysis. By using a UV-vis spectrophotometer, the absorption maxima and molar extinction coefficient were also measured for three acid dyes comparing to that of the corresponding disperse dye or blue dye intermediate. Judging from spectroscopic data, the introduction of sulfonyl groups led to increase of molar extinction coefficient and a bathochromic shift.     

A study of reusing vinyl sulfone based reactive dye for dyeing cotton fiber

Reactive dye is a popular dye for dyeing cotton fiber due to its very good color fastness which is explained by the formation of covalent bond between dye and fiber. In this study, practicality of reuse of reactive dye by compensating for the hydrolyzed part of the dye solution is examined. A monofunctional dye (vinyl sulfone type) was used and it was found that dyeing cotton fiber with reused dyebath is possible. Since bifunctional dye can improve the chance of dye-fiber bond formation, vinyl sulfone based bifunctional reactive dyes were also selected in this study. Three types of bifunctional dyes were used and they basically share the same vinyl sulfone group; other reactive groups are monochlorotriazine, dichlorotriazine and vinyl sulfone. Such dyes were chosen in order to compare their respective efficiencies under the effect of one common reactive group. The aim of this study was to compare the effect of hydrolyzed and unhydrolyzed proportions of mono-and bifunctional reactive dyes on cotton fiber and study the possibility and efficiency of the two different reuse dyebath systems.     

Enzymatic treatment on cotton fibers: degradation kinetics of pectin and influence of shape change on adsorption

Alkaline pectinase was one of the most effective enzymes to treat cotton as alternative agent to replace the conventional alkaline method. Removal of pectin and cutin was considered the explanation for improvement of wettability as well as water adsorption on cotton fiber. However, degradation kinetics of pectin is unclear, and the influence of fiber shape on property changes after enzymatic treatment was ignored. The main objective of this work was to reveal interactions between pectinase and cotton fiber for mechanism study. A heterogeneous catalysis kinetic equation, which is associated with Langmuir adsorption model and enzyme deactivation, was used to describe the heterogeneous catalysis. The enzymatic process conditions were optimized. Raw cotton fibers, pectinase-treated and alkali-treated fibers were characterized by impurities content determination, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM). Mechanism of water adsorption enhancement on treated fibers was discussed. In addition to elimination of the outer impurities, flat fibers with less twist and shape changes of lumen were also obtained to ensure better accessibility and water adsorption after enzymatic treatment.     

Colorimetric studies of benzoquinoline based hot brand monoazo reactive dyes and their dyeing performance on various fibers

A series of hot brand monoazo reactive dyes (9a-l) were obtained by the coupling of diazotized 1Hbenzo[ g]pyrazolo[3,4-b]quinoline-3-ylamine (5) with various cyanurated coupling components (8a-l) in good yield. Synthesized dyes were characterized by various spectroscopic techniques. Their dyeing performances as reactive dyes have been assessed on silk, wool, and cotton fabrics. The percentage dye bath exhaustion and fixation on different fibers were found to be very good. The dyed fabric showed moderate to very good light fastness and good to excellent washing and rubbing fastness properties. Spectral properties and colorimetric data of synthesized dyes have also been studied in detail.     

Dyeing behavior of polyacrylonitrile nanofibers: Physicochemical parameters of dyeing with basic dye in comparison with regular polyacrylonitrile fibers

Polyacrylonitrile nanofibers were produced using the electrospinning method and dyed with a basic dye alongside regular polyacrylonitrile fibers. In order to investigate the effect of high surface area to volume ratio of nanofibers on their adsorption behavior in comparison with regular fibers, the dyeing conditions for both types of fibers were kept just the same. Physiochemical parameters of dyeing such as adsorption isotherm, standard affinity, enthalpy change, rate of dyeing constant, diffusion coefficient, and activation energy of diffusion were investigated for both types of fibers. The results showed that the adsorption process can be well described with the Langmuir adsorption isotherm for both types of fibers whereas the standard affinity of dye to nanofibers was higher than regular fibers and the higher negative values of enthalpy changes were obtained for regular fibers. The nanofibers rate of dyeing was faster than regular fibers with higher amounts of diffusion coefficients and lower amounts of activation energy of diffusion. This study also revealed that in spite of the approximately same amount of dye exhaustion for both types of fibers, the color strength of regular fibers was noticeably higher than nanofibers.     

Synthesis and application of phthalimide disperse dyes

Three azo dyes had been synthesized using N-propyl substituted, dibromo-substituted and dicyano-substituted phthalimides as diazo components. All of the synthesized intermediates and dyes have been characterized by MS, 1H-NMR and IR analyses. The dyeing behaviour and fastness properties of these dyes had been investigated. The absorption maxima of the dyes were observed in the range 360 to 700 nm. The results indicated that dyes caused hypsochromism effect after -Br substitution and dyes caused bathochromism effect after -CN substitution. IR spectra of hydrolyzed dye showed that C=O groups appeared under relatively mild alkaline conditions. Compared with electron density, steric hindrance effect is an more important influence factor than electron density in hydrolysis reaction process. Exhaustion of dyed polyester/elastane fabrics decreased obviously as the pH value increased. In order to ensure dyeing levelness, heating rate of prepared dyes will be strictly controlled. Due to alkali-clearable property and interaction energy of dye-fiber and dye-dye, the dyes have good colorfastness.     

Salt free reactive dyeing of cationized cotton

In this study 3-chloro-2-hydroxypropyltrimethylammonium chloride was used as a cationic agent to cationize cotton fabric by a pad-batch process. The cationized cotton samples were dyed with different reactive dyes containing various reactive groups. The dyeability of the cationized cotton samples with reactive dyes without salt was significantly improved due to an increase in the ionic attraction between the dye and cationized cotton. The results showed that the wash and dry rubbing fastness of the cationized cotton dyed with different reactive dyes are similar to those of the untreated cotton. However, the light fastness of some of the cationized fabric samples was improved.     

Novel cationic softener containing MCT reactive dyes for cotton: Simultaneous dyeing and functional finishing

The cationic softeners containing MCT (monochloro-s-triazinyl) reactive dyes were employed on the dyeing of cotton fabrics. The substantivity, exhaustion, and fixation of the dyes were investigated. It was found that these functional dyes could be effectively introduced to cotton fibers to achieve simultaneous coloration and functional finishing effects. All the dyed fabrics exhibited softening efficacy. The dyes offered excellent washing fastness on cotton substrate. Light fastnesses of the dyes on the substrate were poor.     

Synthesis of temporarily solubilized reactive disperse dyes and their application to the polyester/cotton blend fabric

Five temporarily solubilized reactive disperse dyes were synthesized and characterized. They were applied to polyester/cotton blend fabric using one-bath dyeing method without dispersing agent. The dye that has azonaphthalene chromophore seemed to not only be exhausted on polyester but also react with cotton. But other dyes were selectively dyed on polyester and showed limited uptake on cotton. Good levelling as well as moderate to good colour fastness was obtained with the dyes on P/C blend fabric.     

Dyeing properties of Bombyx mori silks grafted by 2-hydroxyethyl methacrylate (HEMA)

Graft copolymerization technique was selected to improve properties of Bombyx mori silks. The silks were degummed and grafted by 2-hydroxyethyl methacrylate (HEMA), resulting in different graft yields of the degummed silks. It was found that thermal decomposition temperature and wear strength of the silks grafted by HEMA were clearly improved. In addition, dyeing properties of the degummed and HEMA-grafted silks were investigated by using different natural dyes, i.e. coconut shell (Cocos nucifera), pandanus (Pandanus odorus) and Siamese cassia (Cassia siamea) and also synthetic dyestuff, i.e. acid dye. When dyeability and colorfastness properties were investigated, it was observed that higher graft yield of the HEMA-grafted silks exhibited greater dye uptake for all of the applied dyes. Besides, fastness properties to washing, perspiration, light and rubbing of the degummed and HEMA-grafted silks were examined.     

Kinetic, equilibrium and thermodynamic studies of ternary system dye removal using a biopolymer

In this paper, dye removal ability of sodium alginate (SA) as a biopolymer from ternary systems was investigated. Physical characteristics of SA were studied using Fourier transform infra-red (FTIR) and scanning electron microscopy (SEM). Three textile basic dyes were used as model compounds. The adsorption kinetics, isotherms and thermodynamics were studied. The effect of SA dosage, initial dye concentration and pH on dye removal was elucidated. It was found that adsorption kinetics of dyes followed with pseudo-second order kinetics. In addition, dyes followed with Langmuir, and extended Langmuir isotherm in single and ternary systems, respectively. The thermodynamic data showed that the dye adsorption onto SA was a spontaneous, endothermic and physisorption reaction. Based on the data of present investigation, one could conclude that the alginate being a biocompatible, eco-friendly and low-cost adsorbent might be a suitable alternative for elimination of dyes from colored aqueous solutions.     

Performance of cotton fabric treated with an amino-terminated hyperbranched polymer

An amino-terminated hyperbranched polymer (HBP-NH₂), synthesized from methyl acrylate and diethylene tri-amine by polycondensation, was applied to treat cotton samples by a pad-dry-cure method. Physical properties, salt-free dye-ability, antimicrobial activity, and antiultraviolet property of the treated cotton samples were tested. The crystallinity and mechanical properties, including breaking strength, breaking elongation, and Young’s modulus of the treated cotton fibers, increased slightly in comparison with those of the untreated cotton fibers. The thermal stability and the moisture regain were also improved slightly. Dyed with direct dyes and reactive dyes in the absence of the electrolytes, the treated cotton fabric showed similar or higher color strength compared with the untreated cotton fabric in conventional dyeing. The treated cotton fabric can also be dyed with acid dyes effectively. In addition, the treated cotton fabric showed good antimicrobial activities against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The study of the antiultraviolet properties of the treated cotton fabric indicated that the HBP-NH₂ contributed to the reduction of UV transmission and the increase of UPF.     

Morphological structures of the cellulose hybrids containing polyhedral oligomeric silsesquioxane and their application for removing C.I. Reactive Red 250

Cellulose hybrids containing polyhedral oligomeric silsesquioxane (POSS) were synthesized by crosslinking reaction. The chemical and morphological structures of the hybrids were characterized by elemental analysis, infrared spectrum, scanning electron microscope and atomic force microscope. The hybrids were used for adsorbing C.I. Reactive Red 250 in aqueous solution. Adsorption kinetic and equilibrium isotherm of the cellulose hybrids for the dye were investigated. The hybrids formed new adsorptive positions for dyes because of a nanometer-sized cubic core and numerous organic functional groups (-C-N-). The adsorption capacity of the hybrid materials was significantly higher than that of the control cellulose. The adsorption of the dye on the hybrids was good fit with Langmuir isotherm equation and the second-order model. The apparent activation energy of the dye on the hybrid was 14.87 kJ/mol.