Surface and Bulk Modification of Synthetic Textiles to Improve Dyeability

Synthetic fibers, mainly polyethylene terephthalate (PET), polyamide (PA), polyacrylonitrile (PAN) and polypropylene (PP), are the most widely used polymers in the textile industry. These fibers surpass the production of natural fibers with a market share of 54.4%. The advantages of these fibers are their high modulus and strength, stiffness, stretch or elasticity, wrinkle and abrasion resistances, relatively low cost, convenient processing, tailorable performance and easy recycling. The downside to synthetic fibers use are reduced wearing comfort, build-up of electrostatic charge, the tendency to pill, difficulties in finishing, poor soil release properties and low dyeability. These disadvantages are largely associated with their hydrophobic nature. To render their surfaces hydrophilic, various physical, chemical and bulk modification methods are employed to mimic the advantageous properties of their natural counterparts. This review is focused on the application of recent methods for the modification of synthetic textiles using physical methods (corona discharge, plasma, laser, electron beam and neutron irradiations), chemical methods (ozone-gas treatment, supercritical carbon dioxide technique, vapor deposition, surface grafting, enzymatic modification, sol-gel technique, layer-by-layer deposition of nano-materials, micro-encapsulation method and treatment with different reagents) and bulk modification methods by blending polymers with different compounds in extrusion to absorb different colorants. Nowadays, the bulk and surface functionalization of synthetic fibers for various applications is considered as one of the best methods for modern textile finishing processes (Tomasino, 1992). This last stage of textile processing has employed new routes to demonstrate the great potential of nano-science and technology for this industry (Lewin, 2007). Combination of physical technologies and nano-science enhances the durability of textile materials against washing, ultraviolet radiation, friction, abrasion, tension and fading (Kirk–Othmer, 1998). European methods for application of new functional finishing materials must meet high ethical demands for environmental-friendly processing (Fourne, 1999). For this purpose the process of textile finishing is optimized by different researchers in new findings (Elices & Llorca, 2002). Application of inorganic and organic nano-particles have enhanced synthetic fibers attributes, such as softness, durability, breathability, water repellency, fire retardancy and antimicrobial properties (Franz, 2003; McIntyre, 2005; Xanthos, 2005). This review article gives an application overview of various physical and chemical methods of inorganic and organic structured material as potential modifying agents of textiles with emphasis on dyeability enhancements. The composition of synthetic fibers includes polypropylene (PP), polyethylene terephthalate (PET), polyamides (PA) or polyacrylonitrile (PAN). Synthetic fibers already hold a 54% market share in the fiber market. Of this market share, PET alone accounts for almost 50% of all fiber materials in 2008 (Gubitz & Cavaco-Paulo, 2008). Polypropylene, a major component for the nonwovens market accounts for 10% of the market share of both natural and synthetic fibers worldwide (INDA, 2008 and Aizenshtein, 2008). It is apparent that synthetic polymers have unique properties, such as high uniformity, mechanical strength and resistance to chemicals or abrasion. However, high hydrophobicity, the build-up of static charges, poor breathability, and resistant to finishing are undesirable properties of synthetic materials (Gubitz & Cavaco-Paulo, 2008). Synthetic textile fibers typically undergo a variety of pre-treatments before dyeing and printing is feasible. Compared to their cotton counterparts, fabrics made from synthetic fibers undergo mild scouring before dyeing. Nonetheless, these treatments still create undesirable process conditions w

Supercritical CO2 technology in resource-effective production of functional and smart textiles

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Fixation of reactive dyes on cotton using infrared radiation

Le but de ce projet est l'établissement des conditions optimales pour la teinture de coton avec les colorants réactifs aux moyens d'un procédé dans lequel la fixation du colorant s'effectue par rayonnement infrarouge. L'efficacité de ce procédé est comparée aux autres modes de fixation. Les études préliminaires ont montré que le rendement de fixation est plus élevé, plus est élevée la réactivité du colorant, plus est élevée la puissance électrique fournie aux sources infrarouges et plus le temps de séjour est long dans le four infrarouge, respectant toujours la limite de température du tissu qui évite sa dégradation thermique. Le rendement de fixation de certains colorants est assez sensible à la nature et à la concentration de l'alcali utilisé pour amorcer la réaction de fixation. L'addition du sel à la solution du colorant n'augmente que peu les rendements de fixation en accord avec la généralisation que son influence est mineure aux faibles rapports du bain. L'influence de l'addition de l'urée est variable. Elle est capable d'augmenter des rendements de fixation des colorants de faible réactivité. L'extraction sous-vide du tissu imprégné d'une solution alcaline du colorant avant son chauffage dans le four infrarouge améliore la performance du procédé puisque le tissu sèche plus rapidement. Une étude quantitative de l'influence des variables opérationnelles de la thermofixation à infrarouge est effectué [i.e. effectuée] au moyen de plans factoriels et d'analyses statistiques des réponses pour le colorant rouge Drimarene X-6BN. Le procédé de teinture en continu utilisant la thermofixation aux infrarouges pour un colorant de faible réactivité donne un rendement élevé de fixation sans variation de la couleur perçue tout au long de la nappe teinte. Pour un [i.e. une] solution du colorant contenant de l'urée mais sans sel, le rendement de fixation pour le procédé en continu a atteint 90%. La possibilité d'obtenir les hauts rendements de fixation des colorants réactifs au coton (>90%) par application du chauffage infrarouge rend ce procède [i.e. procédé] d'intérêt commercial. Les hauts rendements de fixation possibles sans les addition [i.e. additions] du sel et de l'urée au bain du colorant permettraient une diminution de la charge polluante de la teinturerie."--Résumé abrégé par UM

Treatment of wastewater from textile dyeing by ozonization

Wet processes for textile production are one of the largest water consuming and polluting sources. Quite usually, at the end of the dyeing process, a noticeable amount of dyes remains in wastewater as is not absorbed by fibres, leading to wastewater colouration. Dyes show resistance to degradation in the environment, since their peculiarity is chemical stability. Besides visual problems, the effect of residual dyes is negative on aquatic life because they inhibit sunlight transmission and may enter in the food chain. Generally, conventional biological treatment alone cannot guarantee adequate characteristics to treated water to allow the discharge into the environment or reuse in other processes. Specifically, a high salt content and residual colour are still present in the treated water after secondary treatments. Salt content can be remove using membrane filtration equipment instead the most profitable operation to remove colour appears oxidation. Other techniques, such as coagulation-flocculation, adsorption, membrane filtration, activated sludge, were studied to remove colour but land filling or incineration must be considered as final process. On the contrary, oxidation steps demolish the contaminant at molecular scale, even though not necessary the oxidation is complete. Generally ozone, being an oxidant agent, has a high oxidation potential (even at a low concentration), high efficiency in decomposition of organic matter, adds oxygen to water and has process low sensitivity to changes in temperature. Ozone is able to break up the conjugated bonds of organic matter thanks to a direct reaction between ozone and the organic compound or indirectly through the generation of hydroxyl radicals. The degradation of dyes with O3 is a typical two phase reaction where an effective transfer of ozone from gas to liquid is a critical point. On the other hand, the kinetics of decolouration is usually fast. Therefore, the mass transfer is the rate limiting step. To achieve the best mass transfer condition, several gas diffusers and gas–liquid contactors have been proposed in literature such as turbines, ejectors, gas diffusers (sintered glass diffuser), etc. An innovative operative procedure took into account in this work was cavitation: it was considered as the mean to increase mass transfer of ozone in liquid medium. For this reason, an experimental equipment (Multi-task reactor) was designed and built (Fig. 1). Two types of cavitation were considered: hydrodynamic cavitation by ejector and ultrasound cavitation. The two types of cavitations were used separately or simultaneously in order to clean wastewater from different dyes typology (namely acid, cationic, reactive and disperse dyes). In addition, hydrodynamic and ultrasonic cavitation was used to work alone to decolourise wastewater. Cavitations are able to produce free radicals, such as hydroxyl radicals, which can be used to attack dye cromophores groups of dye molecule. A bubble column reactor was built to compare the decolourisation results obtained in the Multi-task reactor. Bubble column was used as benchmark because represent the most common technology in wastewater decolouration. First of all, decolouration experiments were performed in the multi-task equipment in liquid batch conditions. After that, continuous tests were carried out and the results were compared with bubble column equipment decolouration experiments at the same operational conditions (liquid residence time, gas flow rate, ozone dose, dyestuffs and its concentration). Taking into account the final experiment results, only ultrasound cavitation was able to improve decolouration degree in the case of disperse dye. Comparing the experimental decolouration results obtained with the mentioned technologies, bubble reactor seem to be the best technology for oxidizing treatment. Moreover, fluid dynamic study was performed to bubble column reactor in order to study dye transport mechanisms along the reactor height considering different physical-chemical characteristics. Finally, dyeing test were performed using ozonated wastewater. Wastewater originated from an industrial wool dyeing process was ozonated at different treatment time to obtain different decolouration degree. After that, treated water was reused to dye wool. The benchmark wool dyed with fresh water and wool dyed using ozonated wastewater were compared using a reflection spectrophotometry. In this way, minimum decolouration percentage was discover to obtain a quality parameter to reuse water in dyeing processes, namely color reproducibility

Dyes-environmental impact and remediation

Dyes are an important class of synthetic organic compounds used in many industries, especially textiles. Consequently, they have become common industrial environmental pollutants during their synthesis and later during fibre dyeing. Textile industries are facing a challenge in the field of quality and productivity due to the globalization of the world market. As the highly competitive atmosphere and the ecological parameters become more stringent, the prime concern of the textile processors is to be aware of the quality of their products and also the environmental friendliness of the manufacturing processes. This in turn makes it essential for innovations and changes in these processes, and investigations of appropriate and environmentally friendly treatment technologies or their residues. The large-scale production and extensive application of synthetic dyes can cause considerable environmental pollution, making it a serious public concern. Legislation on the limits of colour discharge has become increasingly rigid. There is a considerable urgent need to develop treatment methods that are effective in eliminating dyes from their waste. Physicochemical and biological methods have been studied and applied, although each has its advantages and disadvantages, with the choice being based on the wastewater characteristics, available technology and economic factors. Some industrial-scale wastewater treatment systems are now available; however, these are neither fully effective for complete colour removal nor do they address water recycling. This chapter outlines the background of dye chemistry, the application areas and the impact of dyeing effluents in the environment. The processes/techniques being implemented and developed for wastewaters remediation are revisited

Development of sustainable chemical technologies using low-cost ionic liquids for waste decontamination and valorization

This work proposed and investigated key strategies that contribute to the advancements of low-cost protic ILs (PILs) for use in the future sustainable chemical industry, particularly in the areas of waste valorization and decontamination. In large, this PhD research contributed to the ongoing development of a lignocellulose fractionation process using PILs. First, the use of contaminated waste wood was investigated as a low-cost alternative feedstock to expensive virgin biomass. Fractionation of post-consumer waste wood collected from construction activities was shown to be highly effective using 1-methylimidazolium chloride [H1Cim]Cl, producing a highly digestible metal-free cellulose pulp, with >70% glucose yield during enzymatic hyrolysis. Evaluation of key process parameters such as solid loading, waste wood composition variation, metal chelation with lignin and IL-clean up were also investigated. The study was expanded to include the valorization of hazardous creosote waste wood using the low-cost PIL N,N,N-dimethylbutylammonium hydrogen sulfate [DMBA][HSO4]. The fractionation produced a highly digestible, PAH-free cellulose pulp stream with 70% glucose release, and a PAH-lignin stream. Second, to develop a better understanding of the process boundary conditions, water use as co-solvent and anti-solvent was investigated using a variety of promising lignocellulosic biomass. It was shown that the impact of water as a co-solvent on the fractionation ability of [DMBA][HSO4] is feedstock-dependent. A reduced water input for lignin precipitation was found not to compromise the cellulose digestibility, while significantly reducing the process energy. In addition, the impact of ionoSolv pretreatment severity on fractionation performance was evaluated using a modified pretreatment severity factor, incorporating the Hammett acidity of the aqueous IL solution. The modified severity factor can better predict the fractionation outcome compared to the classical pretreatment severity factor, particularly regarding delignification and hemicellulose removal. Attention was then turned to utilization of the cellulose pulp derived from the ionoSolv process to produce functionalized nanocellulose crystals (CNCs). Alkaline-H2O2 oxidation was used as a simple and more environmentally friendly method for facile extraction of carboxylated CNCs. The impact of pretreatment severity and cellulose composition on the properties of extracted CNCs was evaluated. The produced CNCs had the ability to form self-standing nanofilms and exhibited similar thermal and colloidal stability to CNCs produced by TEMPO-mediated oxidation. Lastly, a novel approach for textile waste decontamination and synthetic dye reuse using PILs was developed. The PIL [DMBA][HSO4] was used to selectively extract dyes from polyester-based synthetic textiles, leaving the dye-free polyester fiber behind for upcycling. Subsequent dyeing using the dye-rich [DMBA][HSO4] solutions was shown to be possible, achieving a similar color strength to commercially dyed products. The process provides key and novel advantages that can provide a new circular dimension to the textile recycling sector by eliminating virgin dye use, applying a closed-loop solvent-based dyeing process, and creating dye-free polyester fibers.Open Acces

Remoción de negro de Eriocromo T de agua utilizando un material compuesto a base de quitosano/zeolita: un estudio cinético

A composite material was prepared using chitosan and chabazite for the removal of Eriochrome T black dye from water. Scanning electron microscopy (SEM) analyses showed chabazite particles embedded in the chitosan matrix. Thermogravimetric analyses indicated that chitosan degrades chemically at temperatures above 225 °C; chabazite only experiences weight decrease due to moisture loss. Fourier transform infrared spectroscopy (FTIR) analyses on chitosan detected the presence of O-H, N-H, C-H, C-N and C-O bonds, protonated amino groups and saccharides. In chabazite, H2O molecules, T-O and O-T-O groups, where “T” corresponds to Si or Al atoms, isolated H-bonded O-H groups, and Si-O-Si groups were detected. In kinetic experiments, an 86 % decrease of the dye concentration in solution was achieved in approximately 500 minutes. The linearization method was used to evaluate the fit of the experimental data with the pseudo-first-order, pseudo-second order, Elovich and intra-particle diffusion adsorption kinetic models. The kinetic experiments showed that the sorption mechanism corresponds to a pseudo-second order model.Se preparó un material compuesto utilizando quitosano y chabazita para la eliminación del colorante negro eriocromo T del agua. Los análisis de microscopía electrónica de barrido (SEM) mostraron que las partículas de chabazita se incrustaron en la matriz de quitosano. Los análisis termogravimétricos indicaron que el quitosano se degrada químicamente a temperaturas superiores a 225 °C; la chabazita sólo experimenta una disminución de peso debido a la pérdida de humedad. Los análisis de espectroscopia infrarroja por transformada de Fourier (FTIR) en el quitosano detectaron la presencia de enlaces O-H, N-H, C-H, C-N y C-O, grupos amino protonados y sacáridos. En la chabazita se detectaron moléculas de H2O, grupos T-O y O-T-O, donde la “T” corresponde a átomos de Si o Al, grupos O-H aislados y con enlaces H, y grupos Si-O-Si. En los experimentos cinéticos, se logró una disminución del 86 % de la concentración de colorante en la solución en aproximadamente 500 minutos. Se utilizó el método de linealización para evaluar el ajuste de los datos experimentales con los modelos cinéticos de adsorción de pseudo-primer orden, pseudo-segundo orden, Elovich y difusión intra-partícula. Los experimentos cinéticos mostraron que el mecanismo de sorción corresponde a un modelo de pseudo-segundo orden

Production and application of textile materials

This specialized publication is dedicated to technical and technological solutions in textile production. Engineering solutions in the production of fibers and fabrics for both technical and domestic use are considered. Particular attention in the book is given to the study of textile products for biomedical applications. Modern medical fabrics and fibers are used as dressing and suture material and significantly accelerate the recovery processes after surgical operations and burn injuries. Fibers and fabrics are currently often used as a reinforcing element in the production of various composite materials, which are often used in mechanical engineering and in the construction sector. A separate chapter is devoted to textile reinforcing materials. Environmental problems in textile production are mainly related to the dyeing process and the chemical treatment of fabrics and fibers. Some aspects of textile dyeing and wastewater treatment processes are also discussed in this publication. The book will be useful to specialists involved in textile production and related industries

Reduction and Analysis Methods of Indigo

Throughout history indigo was derived from various plants for example Dyer’s Woad (Isatis tinctoria L.) in Europe. In the 19th century were the synthetic dyes developed and nowadays indigo is mainly synthesized from by-products of fossil fuels. Indigo is a so-called vat dye, which means that it needs to be reduced to its water soluble leucoform before dyeing. Nowadays, most of the industrial reduction is performed chemically by sodium dithionite. However, this is considered environmentally unfavourable because of waste waters contaminating degradation products. Therefore there has been interest to find new possibilities to reduce indigo. Possible alternatives for the application of dithionite as the reducing agent are biologically induced reduction and electrochemical reduction. Glucose and other reducing sugars have recently been suggested as possible environmentally friendly alternatives as reducing agents for sulphur dyes and there have also been interest in using glucose to reduce indigo. In spite of the development of several types of processes, very little is known about the mechanism and kinetics associated with the reduction of indigo. This study aims at investigating the reduction and electrochemical analysis methods of indigo and give insight on the reduction mechanism of indigo. Anthraquinone as well as it’s derivative 1,8-dihydroxyanthraquinone were discovered to act as catalysts for the glucose induced reduction of indigo. Anthraquinone introduces a strong catalytic effect which is explained by invoking a molecular “wedge effect” during co-intercalation of Na+ and anthraquinone into the layered indigo crystal. The study includes also research on the extraction of plant-derived indigo from woad and the examination of the effect of this method to the yield and purity of indigo. The purity has been conventionally studied spectrophotometrically and a new hydrodynamic electrode system is introduced in this study. A vibrating probe is used in following electrochemically the leuco-indigo formation with glucose as a reducing agent.Siirretty Doriast