Cationization of cotton for low-salt or salt-free dyeing (original) (raw)
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Cationic Modification of Cotton for Salt-free Reactive Dyeing: A Review
2019
Cotton is still the king of fibres, and most of world‟s apparel is made of cotton due to its unique comfort, good dyeability, ease of production, biodegradability, and relatively low cost. To satisfy consumers aesthetically, cotton products, like garments and household textiles, must have a large color gamut and satisfactory fastness. The most popular dyes for dyeing cotton are the reactive dyes because of their brightness of shade, wide colour gamut, flexible application procedures and all-round good colour fastness properties of the resultant dyeing‟s. In recent years, reactive dyes maintain the largest annual consumption in the world among the dyes used for cotton dyeing. But some problems, such as low dye utilization, large amount of electrolyte used and high volume of wastewater discharged, always exist in the application of reactive dyes. With growing popularity of reactive dyes for dyeing of cotton, environmental problems associated with their use have received attention. Cot...
Effect of a cationising agent on the conventional reactive dyeing of cotton
Coloration Technology, 2008
Cationisation of cotton is emerging as an effective tool that may help to solve the environmental problems associated with the dyeing of cotton with reactive dyes. The efficiency of the cationising agent CA200 has been investigated and was found to be more effective when compared with the usual method for reactive dyeing of cotton. Pretreatment of the cotton fabric with the cationising agent increases the rate of dyeing compared with the existing method of reactive dyeing. The colour yields, in terms of the Kubelka-Munk values as a function of the amount of dye fixed, showed that cationisation enhances the colour strength. It also improves the washing fastness, rubbing fastness and depth of shade. The positive environmental impact of this cationisation process is significant and the cationised cotton shows a similar fabric quality as with the normal dyeing process.
Low-level cationisation of cotton opens a chemical saving route to salt free reactive dyeing
Cellulose, 2023
Cationisation of cellulose fibres has been studied extensively as an alternative to permit salt free reactive dyeing, however chemical balances of the cationisation reaction often are not taken into account. The chemical consumption of cationisation processes described in the literature is substantial and often over-compensates savings in salt in a conventional reactive dyeing. Besides very high consumption of chemicals the high level of cationisation generates problems of uneven dyeings and shade variations. In a new approach low concentrations of 3-chloro-2-hydroxypropyl-N,N,N-trimethylammonium chloride (CHPTAC) were applied in a pad batch cationisation process for cotton fabric to achieve a low level cationisation. The cationic group content of the processed fibres ranged from 5 to 79 mmol kg −1. Exhaust dyeing experiments with Reactive Blue 19 demonstrated that a salt free reactive dyeing is possible with low cationic group content 14 mmol kg −1. The optimised low-level cationisation reduces the overall chemical consumption of the reactive dyeing, and thus represents a cleaner alternative to present reactive dyeing operations which are based on addition of high amounts of salt.
Salt‐free reactive dyeing of cotton
International Journal of Clothing Science and Technology, 2007
PurposeFibre reactive dyes are very popular for cellulosic garments as they are environmentally safe and having good overall fastness properties. But application of these dyes requires a very high concentration of salt. The salt released from garment dyeing increases salinity in drain water stream which has a negative impact on environmental ecology. The present work aims to eliminate the usage of salt during dyeing of cotton goods with reactive dyes.Design/methodology/approachThe methodology adopted here, for the elimination of salt in cotton dyeing, was based on the principle of cationisation (to develop a positive charge) of cotton. The same was achieved by subjecting the caustic pretreated cotton fabric samples to a treatment of 1, 2 dichloroethane followed by methylamine to introduce amino groups in the cellulose structure. The treated cotton when dyed from slightly acidic bath generates positive sites due to protonation in the amino group. The reactive dyes being anionic (nega...
Cationic Modification of Cotton Fabrics and Reactive Dyeing Characteristics
The effect of cationic modification of cotton fabrics, using commercial agent Sintegal V7conc, on reactive dyeing characteristics was studied in this work. The changes after cationization and their effects on practical application of reactive dyes were identified by various methods. Cationically modified fabrics have more positive zeta potential, compared to untreated fabrics, which has a favorable influence on reactive dyeing in the absence or presence of salt. Color intensities of reactive dyes reached their maximum on samples treated with the highest concentration of Sintegal V7conc solution and dyed in the presence of standard salt concentration. The results obtained indicate that color intensity increase is a combined contribution of both salt and cationic agent on adsorption and fixation of reactive dyes on cotton.
Dyeing of cotton using reactive dyes without Salt
In this study 3-chloro-2-hydroxypropyl trimethyl ammonium 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.
Salt free neutral dyeing of cotton with anionic dyes using plasma and chitosan treatments
Environmentally friendly modification of cotton fibers with the aim of improvement of its dyeability with anionic dyes was the main purpose of the current study. Chitosan biopolymer was selected for introduction of cationic moieties to cotton fibers. Plasma treatment was employed to produce the functional sites for attachment of the chitosan to the surface of the fibers. In this study, chitosan was applied on cotton fabric using oxygen plasma pre-treatment. The presence of chitosan on the surface of cotton fibers was approved by SEM images. Untreated and chitosan treated cotton samples were dyed with acid and direct dyes. The effects of salt (sodium sulfate), dyeing time, and initial dye concentration on the color strength of raw and chitosan treated samples were studied.
Cellulose Chemistry and Technology, 2019
Most dyeing processes need a large amount of salt for dye exhaustion from the dye-bath onto fabric, which ultimately results in the discharge of a large amount of saline effluent, producing threats to the aquatic environment. This research investigates the cationization of cotton fabric, which avoids the consumption of salt during dyeing. Pretreatment of fabric was carried out using a commercially available cationic agent named 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC). Then, pretreated fabric was subjected to dyeing using solubilized Sulphur Black dye. The pretreated fabric presented increased color strength values and colorfastness properties.
Interface phenomena and dyeability with reactive dyes of cationized cotton
Industria textilă
Interface phenomena have a significant role in wet finishing processes of cotton. Therefore, interface phenomena of cotton fabric, cationized with commercial cationic compound, were studied in this paper. The characterization of surface after cationization, was performed by FTIR-ATR and SEM. Interface phenomena were studied through electrokinetic phenomena, surface free energy and adsorption. Zeta potential, isoelectric point and point of zero charge were determined according to streaming current/streaming potential method; specific amount of surface charge and adsorption of a ionic surfactant by potentiometric titration method, surface free energy by thin layer wicking method. The affinity of such modified cotton for reactive dyes having different functional groups was investigated through the K/S values. The effect of electrolyte addition on dye bath was investigated as well.