Dyeing Process In Industry Research Articles

Simulation of an industrial scale scCO2 beam dyeing process

An industrial dyeing process in supercritical carbon dioxide has been modelled with computational fluid dynamics using Ansys Fluent software. In order to investigate the distribution of the dye carrier fluid, the flow resistance of the fabric has been accurately characterised. For this purpose, in the first part of the work a plain-woven fabric geometry was created in the open software Tex-Gen and modelled in Ansys Fluent to predict the permeation of fluid through the pores of the fabric material and to estimate the relationship between local fluid velocity and pressure drop. The second part of the study focused on evaluating the influence of beam structure, inlet flow rate, fabric height on the fluid flow through the fabric, which must be uniform to achieve a homogeneous level of dyeing. From the simulations the main obstacle to achieving a uniform flow velocity in the fabric is the pressure rise that occurs in the beam and creates a slight difference in permeation velocity between the two axial ends of the fabric; other disturbances, such as the effect of the perforated structure of the beam, are usually minor. Due to the low viscosity of supercritical carbon dioxide, inertial losses predominate over viscous losses in the porous medium. This means that approaches based only on the permeability of the fabric and the application of Darcy's law are inadequate to correctly predict the response of a dyeing unit when using carbon dioxide.

Fabric dyeing with colorimetric pH‐responsive colours

AbstractThis paper explores the possibility of dyeing textile fabrics with halochromic dyes. Five different halochromic dyes were tested: bromocresol purple, m‐cresol purple, chlorophenol red, curcumin and bromothymol blue. Preliminary dyeing was carried out on wool, polyacrylonitrile, polyester, polyamide 6.6, cotton and cellulose acetate at 100°C for 40 minutes to evaluate affinity. All the dyes showed good affinity to wool and polyamide 6.6. Cotton required a mordant phase before dyeing. Washing and light fastness were evaluated for the dyed fabrics, as well as colour changes at different pH values. Some fibres displayed good dye fastness and halochromic properties. Bromothymol blue was selected to dye polyamide 6.6 and cotton fabrics. The dyed fabrics displayed good halochromic properties across a pH range of 4 to 10. Cotton fabrics exhibited an immediate colour change; polyamide 6.6 changed colour after several minutes. An industrial dyeing process was performed on natural cellulosic fibres. The results confirmed the possibility of scaling up the process with regard to textile applications of halochromic dyes.

Use of the β-Cyclodextrin Additive as a Good Alternative for the Substitution of Environmentally Harmful Additives in Industrial Dyeing Processes

In this work, the substitution of environmentally harmful additives in the industrial dyeing process of polyamide-6 microfiber-made knitted fabrics (PA-6µFKF) was studied. Using the disperse red 60 (DR60) dye, kinetic adsorption tests on the PA-6µFKF dyeing were performed by using either β-cyclodextrin (β-CD) additive, commercial leveling agents, or without additives. Equilibrium tests were also performed during 25 h. A modelling based on a dye adsorption process controlled by an intraparticle diffusion was proposed to represent the sets of kinetic data. Three isotherm models were also tested for representing the equilibrium data. The kinetic data have evidenced three main dye diffusion zones. Different adsorption mechanisms on PA-6µFKF surface dyeing was evidenced, being the data well represented by the two-step Langmuir isotherm. Finally, the best quality on color uniformity was attained using the β-CD additive, revealing a good alternative for the substitution of environmentally harmful additives in industrial dyeing processes.

Making conductive graphene yarn in bulk

A fast and easy method to produce conductive graphene yarn in bulk could open the door to mass production of wearable textile electronics (ACS Nano 2019, DOI: 10.1021/acsnano.9b00319). Nazmul Karim and Kostya S. Novoselov of the University of Manchester and colleagues made the flexible, washable yarn using an industrial dyeing process capable of producing 1,000 kg of the yarn in about half an hour, they say. The key is a new graphene-based dye. To make it, the researchers first dispersed graphene oxide flakes in water, then used ascorbic acid and sodium hydrosulfite to partially reduce the flakes to graphene. Next, they added polymers to the solution to prevent the flakes from clumping. They dyed a hank of cotton yarn with this solution using a lab-scale replica of a commercial yarn-dyeing machine. The partially reduced graphene oxide flakes retain some oxygen-containing functional groups that bond with the cellulose in the cotton,

Functionalization of textiles with multi-walled carbon nanotubes by a novel dyeing-like process

Multi-walled carbon nanotubes (MWCNTs) were functionalized with oxygen-containing surface groups and subsequently incorporated in cotton and polyester fabrics by a process that mimics the traditional industrial dyeing process. The washing fastness, hydrophobicity and flame retardancy of the functional textiles were evaluated. The MWCNTs surface chemistry was modified by three different routes: (i) liquid phase oxidation with nitric acid, in order to introduce acidic oxygen-containing groups, (ii) thermal treatment of the sample oxidized in (i), in order to remove the carboxylic acid functionalities and (iii) gas phase oxidation with 5% oxygen in nitrogen to incorporate basic and neutral groups. All samples were characterized by temperature programmed desorption, pH at the point of zero charge and N2 adsorption–desorption isotherms at −196 °C. The effect of the MWCNTs acidity/basicity and of the type of substrate in the nanomaterials incorporation efficiencies and in the performance of the final textile materials was assessed. The scanning electron microscopy images and the whiteness degree values of the functional textiles before and after washing indicated that the incorporation efficiency was higher for the textiles containing the most acidic MWCNTs, especially for the polyester textiles. The immobilization of the less acidic MWCNTs in polyester imparted hydrophobic properties to the fabrics surface; in particular, the polyester samples functionalized with unmodified and O2-oxidized MWCNTs presented an almost superhydrophobic behaviour. In the case of the cotton-based samples, a hydrophobic behaviour was not achieved. Finally, the flame-retardant properties of both substrates improved upon the MWCNTs immobilization.

Quantification of Textile Dyes in Industrial Effluent Using UV-Vis Spectrophotometry Combined with Principal Components Regression

UV-Vis spectrophotometry and multivariate calibration model, Principal Components Regression (PCR), were used for individual and simultaneous quantification of ternary mixtures of reactive dyes (Yellow Procion HE4R, Navy Blue Procion HER, and Blue Procion HEGN) in a sample of industrial effluent and effluents obtained in the laboratory. A Centroid-Simplex-type experimental design was used. The percentages of the dyes Yellow Procion HE4R, Navy Blue Procion HER, and Blue Procion HEGN not fixed to the fiber in the industrial dyeing process and laboratory scale were 47.40%, 10.99%, 24.72% and 4.20%, 46.06%, 32.04%, respectively.

Pilot-scale Enzymatic Decolorization of Industrial Dyeing Process Wastewater

Manuela Lageiro and Maria Costa-Ferreira1 Bioengineering and Bioprocessing Unit, Department of Biotechnology, National Institute for Industrial Engineering and Technology (INETI), Portugal Abstract An enzymatic cocktail was used for the decolorization of process wastewater, containing mainly three reactive azo dyes, from a textile dyeing and printing company. Water sampled from different processing streams and combinations thereof was decolorized to different extents. The decolorization was greatest for C.I. Reactive Black 5, followed by C.I. Reactive Red 158, whereas C.I. Reactive Yellow 27 was the least decolorized. As wastewater from the printing process was inhibitory, the 1 mistirred tank type reactor prototype was installed near the outlet prior to the discharge of wastewater from the printing process. Temperature and pH control systems were installed to ensure optimal enzymatic decolorization, this being about 45 ° C and pH 6.4. The average temperature observed at the reactor was 42.1 ° C, which indicated the need for improved temperature control. Laboratory scale tests were done to assess the reuseability of the biotreated wastewater for the washing of dyed cotton fabrics.