NOVEL COMBINATION OF TRISODIUM CITRATE AND TRISODIUM PHOSPHATE IN REACTIVE DYEING OF COTTON: AN ATTEMPT TO REDUCE ENVIRONMENTAL IMPACT

"Reactive dyes are most widely used for dyeing cellulosic fabrics due to their excellent wet fastness properties, the brilliancy of shades and a wide gamut of colours. However, the exhaustion of reactive dye requires a large quantity of inorganic electrolyte, which results in excessive total dissolved solids (TDS) values of the resultant effluent. Such high TDS-containing effluents are challenging to treat and require advanced treatment techniques. The discharge of high-TDS containing effluent into water-bodies can increase the salinity of the aquatic system, which can affect the delicate biochemistry of the aquatic life. This necessitates the exploration of alternative chemicals for reducing the TDS of the effluents in reactive dyeing. The current study explores the alternate combination of trisodium citrate (TSC) and trisodium phosphate (TSP) as an eco-friendly replacement of inorganic salts and alkali in the dyeing of cotton by the exhaust process. The TSC-TSP combination resulted in an insignificant variation in exhaustion, fixation and fastness ratings compared to the conventional salt-soda combination. The colour values showed marginal variations in the individual cases of dyes. However, the use of the TSC-TSP combination showed a great promise in reducing the TDS of the effluent (by 66%), which is a major concern in effluent treatment. TSC being organic, some increase in COD/BOD values was obtained; however, the effluent remained in a category of easily treatable ones. "

Surface functionalization of greige cotton knitted fabric through plasma and cationization for dyeing with reactive and acid dyes

Dyeing cotton fabrics with anionic dyes produces high effluent loads and requires a considerable amount of water and energy due to the electrostatic repulsion with cellulose. Therefore, several approaches have been researched to increase the efficacy of cotton dyeing. One is the cationization, which adds cationic sites to the cellulose. Another is the treatment of the cotton surface with plasma. In this paper, the combination of both techniques was investigated. Two commercially available cationic agents were used: 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) and poly[bis(2-chloroethyl) ether-alt-1,3-bis[3-(dimethylamino)propyl]urea] quaternized, a novel cationic agent also known as Polyquaternium2 (P42). The plasma treatment was performed using a dielectric barrier discharge atmospheric plasma facility, helium was used as seed gas and 1.5 % of oxygen was injected. The cationization and plasma treatment were performed on greige cotton fabric, an innovative and sustainable approach that eliminates conventional scouring and bleaching processes. The cationic and plasma treated samples were dyed using Reactive Red 195 and Acid Blue 260 dyes. The effect of the treatments was evaluated by different characterization techniques such as X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The plasma treatment slightly increased the light fastness for some samples, but the cationization tends to prevail over the plasma treatment. The best results were attributed to the samples pretreated by CHPTAC, which presented the highest K/S and lowest unlevelness for samples dyed with reactive and acid dyes. CHPTAC is the most common cationic agent for textiles, but its industrial use is limited due to safety criticisms. The combination between plasma and P42 resulted in the same color strength as the conventional reactive dyeing. Therefore, this approach offers a safer alternative to the conventional cationization process.

Sustainable Dyeing of Cellulosic Fabric with Reactive Violet H3R dye: Ultrasonic Assisted Improvement in Color Characteristic

Ultrasonic radiation (U. S.) is the sustainable and green technology which has transformed the domain of textiles. In the current study, ultrasonic treatment was employed to improve the reactive dyeing of cellulosic fabricby Violet H3R dye. For this purpose, U.S. treatment has been given to both solution & fabric upto 50 min. at 30 to 60 oC. Promising results were obtained when cellulosic fabric was exposed to U.S. treatment at at 50 oC for a period of 30 min. using dye bath of 55 mL having 7.5 pH. Glauber salt (8 g/L) was employed as an exhausting agent at 60 oC for 55 min. Various shades of cotton fabric dyed at optimal conditions were obtained which showed that U.S. treatment has enhanced not only the colour strength but also the fastness rating from medium to outstanding. So, it can be concluded from the current study that U. S. treatment is not only good enough for improving the dyeing aptitude of Reactive Violet H3R dye but it also uplifts the color features of dyed cotton fabric. Resumen. La radiación ultrasónica (U:S. por sus siglas en inglés) es la tecnología sostenible y verde que ha transformado el campo de los textiles. En este estudio, se llevó a cabo un tratamiento ultrasónico para mejorar el teñido reactivo de tela celulósica por el tinte Violet H3R. Para este propósito, se llevó a cabo un tratamiento con ultrasonido tanto a la solución como a la tela por hasta 60 minutos a 30 y 60 oC. Se obtuvieron resultados prometedores cuando la tela celulósica se expuso a un tratamiento con ultrasonido a 50 oC durante un período de 30 min, utilizando un baño de tinte (de 55 mL) a pH 7,5 de sal de Glauber (8 g/L). Estas condiciones representan un sistema de agotamiento, aplicado a 60 oC durante 55 min. Se obtuvieron varios tonos de tela de algodón teñidos en condiciones óptimas, lo que mostró que el tratamiento por ultrasonido mejora no solo la intensidad del color sino también el índice de solidez de media a sobresaliente. Por lo tanto, del estudio actual se puede concluir que el tratamiento con ultrasonido no solo es lo suficientemente bueno para mejorar la capacidad de teñido del tinte Reactive Violet H3R, sino que también realza las características del color de la tela de algodón teñida.

A Salt-free and Water-saving Approach as a Green Alternative to Conventional Reactive Dyeing of Cotton

Aqueous reactive dyeing of cotton is considered to be environmentally unfriendly owing to its high consumption of water and salt as well as large discharge of wastewater. However, the industrial applications of current alternative dyeing technologies are difficult to realize due to different problems such as poor dyeing quality, environmental pollution and high cost. Herein, we developed a hydrophobic deep eutectic solvent (HDES) dyeing approach using natural thymol-menthol to overcome the problems caused by reactive dyeing of cotton. HDES dyeing approach could achieve excellent dyeing properties of cotton by optimizing water content, pick-up and concentration of alkali solution. Dye fixation kinetics of HDES dyeing system was studied based on Lagergren pseudo-first-order and pseudo-second-order dynamics models, compared with aqueous dyeing system. The cotton fabrics dyed in Thy-Men system exhibited excellent levelness, satisfactory colorfastness and color strength without addition of salt. Furthermore, HDES can be reused for 5 cycles of dyeing and the dyed fabrics displayed consistently high color strength values. This dyeing approach provides substantial reduction in wastewater emission and consumption of freshwater and chemicals, which has considerable potential for promoting cleaner production in the textile industry.