Keratin hydrolysate as an exhausting agent in textile reactive dyeing process

Salt is an essential exhausting agent for the dyeing of cotton fabric with reactive dyes. The usage of salt leads to an increased effluent load in terms of total dissolved solids and also limits the opportunities for recycling textile dye house effluents. These effluents are difficult to degrade and their disposal leads to environmental pollution. In the present work, we have prepared keratin hydrolysate (KH) from waste of wool processing industries to reduce the usage of salt in dyeing. The KH was fixed to the cotton fabric at five different add on percentage, and the presence of the KH on the fabric was confirmed by FTIR, TGA and SEM-EDX Studies. The KH-fixed fabrics were further dyed with reactive dyes without addition of salt. The colour strength of the fabric increased up to 91 % to that of the control sample. The studies reveal that the tone of the fabric was not altered and KH usage can significantly reduce salt consumption in reactive dyeing process.     

Functionalized fibrous materials for the removal of dyes

Wastewater effluents from textile industry mainly contain dyes used in the dyeing or printing of textiles yarns or fabrics. A lot of technologies can be adopted for dye removal from wastewaters, including biological treatments based on activated sludge, adsorption on activated carbon, or membrane processes. Nevertheless, none of these methods is performing toward all classes of dyes; treatment plants of great dimensions and difficult handling can be required, while cost can be prohibitive. In the present study, dye adsorption was performed on low-cost fibrous cellulose materials, submitted to a cationization process using a quaternary ammonium reagent. These materials were characterized by FTIR–ATR spectroscopy, while the treatment efficiency was investigated through exhaustion and kinetic adsorption tests toward anionic dyes, such as acid, direct, reactive, and a cationic dye. Comparisons were carried out between treated and untreated samples, and with activated carbon. Best results were obtained with cationized cotton, both in linters or “tulle” fabric form, showing good performance toward all the investigated dyes. Tests in continuous flow confirmed the good behavior of these materials, but tulle fabric was better as filtration medium for a lower pressure drop. Finally, regeneration tests by bleaching were carried out finding that regenerated material maintained good adsorption power.     

Optimization of proteases pretreatment on natural dyeing of wool using response surface methodology

Natural dyes and enzymes have attracted a lot of attention due to their non-hazardous nature. In this research, wool fabrics were pretreated with the commercial protease at different concentrations over various times. The dyeing process was then carried out on the treated fabrics with the commercial madder and cochineal. Also, the central composite design analysis was used to design the relation between dye exhaustion and some properties of dyed wool including tensile strength, alkaline solubility, water drop absorption, and weight loss based on Design of Expert software. The response surface methodology was also applied to find the optimum conditions for the wool fabric pretreatment. The scanning electron microscopy was employed to indicate the influences of proteases on the fabric surface. The optimized proteases pretreatment on the wool surfaces has considerably improved the absorption of madder and cochineal and minimized the damage to appropriate physical properties. The adsorption kinetic of madder and cochineal on enzymatic wool fiber was fitted with a pseudo-second-order model. The rate of dyeing at different temperatures, as well as the values of standard affinity, entropy, and enthalpy, was calculated. The activation energy of dyeing with madder and cochineal at different temperatures are 23.79 and 30.96 kJ/mol, respectively, considering that these values are in the typical activation energy for physisorption. It was also found that wash, light, wet and dry rub fastness properties of the samples dyed along with protease have not changed significantly. This can be easily scaled up in the industry as a simple method using the commercial materials.     

多羧酸基水溶性硫化染料染色和防皱整理双功能性研究

对合成的含多羧基水溶性硫化黑的染色和防皱整理双功能性进行了研究。考察了在以双氰胺、磷酸二氢铵及三乙醇胺等作为染色助剂情况下对合成染料染色效果的影响。该多羧酸基水溶性硫化染料在磷酸二氢铵及三乙醇胺等助剂存在及合适的焙烘温度下固色率能达到98．1％,同时被染棉织物显示出3级的良好湿摩擦牢度与优良的抗皱性能。     

Reduction of colorants in nylon flock dyeing effluent

The batch dyeing of fiber materials such as staple fibers and flock is usually carried out by exhaustion methods. However, the dyeing of flock fibers, either nylon, PET or acetate, with acid or disperse dyes is not 100% efficient in terms of dye utilization. Therefore, the remaining dyes in the spent dye bath are generally not reused, and are usually discharged with minimum treatment, together with the dyeing chemicals into the sewage wastewater system causing environmental pollution. We found that the colorants and chemical auxiliaries in the fiber dyeing effluents can be reduced by: (1) optimizing the acid dyeing conditions such as salt addition and pH control; (2) reuse of the spent dye bath that remain after the original dyeing process. In the lab scale trials, we have successfully raised the acid dye exhaustion to over 90% by optimizing the dyeing conditions. The reuse of the spent acid dye bath also showed promising results with dye exhaustion ranging from 91 to 93% after four times of reuse.     

UV Excimer laser modification on polyamide materials: effect on the dyeing properties

Polyamide (nylon 6) fabrics were irradiated with 193 nm ArF Excimer Laser and then dyed with commercially available acid, disperse and reactive dyes. The morphology of the irradiated surfaces was examined by scanning electron microscopy (SEM). Chemical surface changes of the materials were characterized by X-ray photoelectron spectroscopy (XPS) and change in crystallinity was examined by differential scanning calorimetry (DSC). Polyamide materials irradiated with laser developed ripple-like structures of micron size on the surface. These structures are strictly perpendicular to the stress direction of the fiber. It is worth noting that the dyeing properties of all dyes on polyamide fabrics changed remarkably after the treatment. The change in color is believed to be closely related with the appearance of ripple-like structures. Changes in chemical properties of the treated materials may also be one of the reasons for dyeability changes. This work suggests that the dyeing properties of disperse and reactive dyes on nylon can be improved after laser modification. Electronic Publication     

染料与纤维共磨对纸浆模塑染色和强度性能的影响

目的探究深色纸浆模塑制品染色过程中出现色差的机理,研究染料与纤维共磨对染色效果和强度性能的影响,提出改善深色纸浆模塑制品染色效果与强度性能的工艺。方法在相同磨浆转数下,探究染料的加入方式对纤维形态、染色制品强度、光学性能及染料上染率的影响;将染料与纤维共磨,探究不同磨浆转数对浆料的滤水性能、染色制品的染色效果和强度的影响。结果实验证实,染料和纤维共磨有利于改善染色制品的抗张强度和耐破强度,能在显著提高染色效果的同时有效降低染色制品的正反面色差。与传统添加方式相比,染色制品的色差由2.53缩小到0.20,上染率从72.02%提高到了77.93%。显微镜图像分析显示,共磨浆料的纤维起毛现象更明显。此外,随着磨浆转数增加,染色制品的光学性能和强度性能得到提高。结论染料与纤维共磨可以提高打浆效果,改善深色纸浆模塑制品的染色效果和强度性能。     

Is it feasible to use dyed wool powder as pigment?

In order to make better use of wool powder and explore the feasibility of replacing pigment with dyed wool powder, the dyeing behavior of wool powder was studied firstly. Then, we conducted a series of tests and analyses of the microcosmic structure and properties of powder before and after dyeing. BET test results revealed that the specific surface area of original powder was larger than that of dyed powder. TG and DMA tests indicated that the dyed powder had better thermal stability than the original powder. At last, the dyed wool powder and pigment were mixed and printed on cotton fabric. The dry/wet-rubbing fastness and moisture permeability of cotton fabric printed with dyed powder are better than those of cotton fabric printed with pigment. This indicates that the waste- wool fiber can be processed into applicable printing pigments, which is environmentally friendly and makes full use of natural resources.     

Antimicrobial finish of textiles by chitosan UV-curing

The purpose of this research work was to develop a textile finish based on the radical UV-curing of chitosan on textiles to confer antimicrobial properties. Chitosan is a biopolymer with unique properties such as biodegradability, non-toxicity, antimicrobial activity. In this work cotton or silk fabrics and synthetic filter fabrics were impregnated with an acid solution of chitosan added of the photoinitiator in the proper amount and cured at room temperature by exposure to UV lamp. Process conditions such as percentage add-on, dilution, chitosan-fabric contact time, irradiation time and power, were optimized. The antimicrobial activity of finished fabrics was tested according to ASTM E 2149-01 standard test performed with Escherichia Coli ATCC 8739. Moreover dyeing test with Turquoise Telon dye were carried out to evaluate the treatment homogeneity while the amino group content was determined by ninhydrin assay. Moreover on cotton and silk fabrics the treatment fastness to domestic laundering was tested, according to UNI EN ISO105-C01. Obtained results showed a strong antimicrobial activity conferred by the treatment, homogeneous on fabric surface. It is evident already at low add-on, without affecting the hand properties of natural fabrics and the filtration characteristics of the synthetic filter fabrics. Finally, washing fastness was better for samples prepared with a better penetration of chitosan inside the fibers.     

Light Stability of New Polaroid Colour Prints

The new Polaroid ® instant colour print system, SX-70, uses metallized dyes, cyan, magenta, and yellow, which have superior light fastness properties. Structures for the dye developers are given, and also comparative fading data for the colour prints and a high quality commercial chromogenic colour print material. A further step of improvement has been achieved in another experimental colour print material using the same dyes. In the SX-70 print the processing chemicals remain with the picture.     

Coagulation-flocculation-decantation of dye house effluents: concentrated effluents

The treatment and valorization (recycling of water and mineral salts) of dyeing effluents constitutes a major economic and environmental issue. Cotton dyeing using reactive dyes is actually the most polluting in terms of discharge. In order to treat and valorize the effluent from a dyeing process using reactive dyes, the firm Clariant and the LPPE have developed and patented a process allowing the recovery of most of the water and salts present in the effluent and also of a concentrate containing the hydrolyzed reactive dyes and the highly concentrated auxiliaries. This paper describes the coagulation-flocculation-decantation process used to optimize water recovery from the concentrate. Coagulants and flocculants are used in the industry for the treatment of effluents produced by the synthesis of dyes in general (acid, disperse, reactive). Although the settling velocity is relatively low, the results show that it is possible to recycle a great volume of water using a small decanter area, since the concentrate flow rate is low. These effluents are substantially discolored, it possible to envisage recycling them.     

Environment and energy efficient dyeing of woollen fabric with sticta coronata

For a trial to improve the natural dyeing cultural heritage to meet the environmental future demands technology to reach high quality dyed patterns. This paper deals with extraction, dyeing of woollen fabric with “Sticta Coronata” under ultrasonic energy and glucose/hydrogen peroxide based redox system. The efficiency of ultrasonic-assisted extraction in presence of 9:1 water:acetone solvent and dyeing in presence of redox system, followed by alum mordanting have been studied in compared when the system was absent and the traditional thermal technique. The influence of redox system, ultrasonic energy and alum mordanting on the rate of dyeing and dye fixation has been demonstrated, and the mechanism of glucose/hydrogen peroxide redox system has been tentatively suggested. The extraction with 9:1 water:acetone solvent possesses higher absorbency in shorter extraction time compared with the aqueous one. Redox system reduced the rate of dyeing at lower temperature with significant enhancement on the dye exhaustion and fixation, involving covalent bonding in addition to the usual coulombic bond. Mordanting process exhibited negligible effect and might decline the percentages of dye exhaustion and fixation in presence of redox system. Ultrasonic energy provided easy efficient route for dye extraction, dyeing, and mordanting processes in compared with the traditional thermal technique.     

Electrochemical-assisted photodegradation of mixed dye and textile effluents using TiO2 thin films

Mixed dye consists of six commercial dyes and textile effluents from cotton dyeing process were treated by electrochemical-assisted photodegradation under halogen lamp illumination. Two types of effluents were collected which are samples before and after undergone pre-treatment at the factory wastewater treatment plant. The photodegradation process was studied by evaluating the changes in concentration employing UV-vis spectrophotometer (UV-vis) and total organic carbon (TOC) analysis. The photoelectrochemical degradation of mixed dye was found to follow the Langmuir Hinshelwood pseudo-first order kinetic while pseudo-second order kinetic model for effluents by using TOC analyses. The chemical oxygen demand (COD) and biochemical oxygen demand (BOD) values of mixed dye and raw effluents were reported. Photoelectrochemical characteristic of pollutants was studied using the cyclic voltammetry technique. Raw effluent was found to exhibit stronger reduction behaviour at cathodic bias potential but slightly less photoresponse at anodic bias than mixed dye.     

Identification of natural dyes on laboratory-dyed wool and ancient wool, silk, and cotton fibers using attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy and Fourier transform Raman spectroscopy

Attenuated total reflection (ATR) infrared and Fourier transform (FT) Raman spectra were obtained from wool threads dyed in the laboratory with natural dyes used in antiquity, following a procedure similar to ancient methods for dyeing wool. The ATR spectra were primarily dominated by the signals of the wool, making it difficult to identify the dye on the fibers only by visual inspection of the infrared spectrum. However, the Raman spectra showed more significant characteristics attributable to the dyes as previously studied in the literature on modern synthetic dyes. A library-search method was thus applied to the second derivatives of both the ATR and Raman spectra to verify the possibility of identifying the dye. Two libraries were constructed, one consisting of the ATR spectra of undyed wool (raw, washed, and mordanted) and the transmission spectra of pure dyes and the other consisting of the Raman spectra of undyed wool and of pure dyes. Correlation and first-derivative correlation search algorithms were used. The results presented here suggest that the two types of spectroscopy are complementary in this kind of work, allowing the almost complete identification of historic dyes on wool. In fact, through the combined use of the two searches, most dyes were identified with a good index of similarity and within the first five hits. Only for annatto was identification totally impossible using either technique. Subsequently the same method was applied to wool, silk, and cotton threads taken from ancient Caucasian and Chinese textiles.     

Photocatalytic degradation of rhodamine B dye using hydrothermally synthesized ZnO

The sunlight mediated photocatalytic degradation of rhodamine B (RB) dye was studied using hydrothermally prepared ZnO (T = 150°C andP ∼ 20–30 bars). Zinc chloride was used as the starting material along with sodium hydroxide as a solvent in the hydrothermal synthesis of ZnO. Different durations were tried to obtain pure ZnO phase, which was later confirmed through powder X-ray diffraction. The photocatalytic behaviour of the prepared ZnO was tested through the degradation of RB. The disappearance of organic molecules follows first-order kinetics. The effect of various parameters such as initial dye concentration, catalyst loading, pH of the medium, temperature of the dye solution, on the photo degradation of RB were investigated. The thermodynamic parameters of the photodegradation of RB, like energy of activation, enthalpy of activation, entropy of activation and free energy of activation revealed the efficiency of the process. An actual textile effluent containing RB as a major constituent along with other dyes and dyeing auxiliaries was treated using hydrothermally synthesized ZnO and the reduction in the chemical oxygen demand (COD) of the treated effluent revealed a complete destruction of the organic molecules along with colour removal.     

Decolourization of azo dyes using magnesium-palladium system

Magnesium-palladium system was found to efficiently decolourize reactive black 5, sunset yellow FCF and tartrazine dyes. There is complete loss of visible range absorption peaks and extent of colour removal exceeded 95% within 24 h of reaction. There is appearance of new peak(s) in the UV region and/or gradual and significant shift of the lambda(max) in the UV range during 1-24 h of reaction of dyes with Mg/Pd system. LC-MS analyses following the reaction of dyes with magnesium palladium system suggest reductive cleavage of azo bonds and formation of amines as the end products. Kinetic analyses of dye decolourization indicate that the reaction follows first order kinetics. Agreement between the experimental and predicted Michaelis-Menten plots for the decolourization of reactive black 5, sunset yellow FCF and tartrazine dyes by Mg(0)/Pd(4+) system, suggests the correctness of Michaelis-Menten model for the prediction of dye decolourization rates by Mg(0)/Pd(4+) system. Our investigations reveal that Mg(0)/K(2)PdCl(6) system is more effective in decolourizing dyes as compared to Mg(0)/Pd(0)-alumina or Mg(0) alone. Results obtained from reuse experiments suggest that Pd(0) pellets have the potential for recycling which will make the treatment process cost effective. Mg(0)/Pd(4+) system was found to be efficient in decolourizing mixture of drimarene, remazol and procion dyes as well as raw effluent generated by textile dye manufacturing company.     

Comparison of disperse and reactive dye removals by chemical coagulation and Fenton oxidation

The composition of wastewater from the dyeing and textile processes is highly variable depending on the dyestuff type and typically has high COD and color. This study examined the decolorization of some of the most commonly used disperse and reactive dyestuffs by combination of chemical coagulation and Fenton oxidation. In addition, performances between Fe3+ coagulation and Fenton oxidation of dye solutions were compared by measuring COD and dye removals, distributions of zeta potential, concentration of suspended solid were investigated. Fenton oxidation in combination with Fe3+ coagulation has shown to effectively remove COD and dye. About 90% of COD and 99% of dye removals were obtained at the optimum conditions. Compared to reactive dyes, disperse dyes have lower solubility, higher suspended solids concentrations and lower SCOD/TCOD ratios. The COD and dye removed per unit Fe3+ coagulant added for disperse dye solutions were higher than those for reactive dye solutions. Therefore, the disperse dye solutions are more easily decolorized by chemical coagulation than reactive dye solutions. Conversely, reactive dye solutions have higher applicability of Fenton oxidation than disperse dye solutions due to their higher solubility, lower suspended solids concentrations and higher SCOD/TCOD ratios. The COD and dye removed per Fe2+ Fenton reagent added for reactive dye solutions are respectively higher than those for disperse dye solutions.     

An eco-friendly option for less-chrome and dye-free leather processing: in situ generation of natural colours in leathers tanned with Cr–Fe complex

A chromium–iron tanning agent has been prepared and used for tanning with the objective of high exhaustion of chromium. Chromium–iron tanned leathers exhibit comparable shrinkage temperature and strength properties with those of conventional chromium tanned leathers. There is no change in strength or colour on ageing the leathers for 1 year. Spent tan liquor analysis reveals that the exhaustion of both the metals is more than 90%. Dyes based on synthetic formulations are being widely used in the leather industry. However, it is known that many aryl amine dyes are banned because of their carcinogenic nature. Environmental concern leads one to look for dyes based on natural resources. A novel approach has been taken to achieve an eco-friendly coloration process utilizing the presence of iron in the tanning salt, which gives rise to various colours on reacting with vegetable tannins. Skins have been tanned with Cr–Fe tanning salt and complexed with different vegetable tanning materials such as myrobalan and quebracho at various concentrations. Colours such as brown, black and grey have been developed. The colour shades obtained have been quantified by reflectance measurements. Thus, the study provides not only clean processes for a greener environment but also clean leather without harmful synthetic dyes. Electronic Publication     

Photochemical Activity of Merocyanine Dyes

Time-resolved photothermal responses of merocyanine dyes were used to estimate such parameters as the quenching rate constant of dye triplet states and dye capability of singlet oxygen generation, which are helpful in explanation of the dye photochemical activity. The results have shown that the high photostability of the salt form of merocyanine dyes and their resistance against reactive oxygen species as well as dye–oxygen interaction by triplet–triplet energy transfer make merocyanines efficient singlet oxygen generators in simple and complex systems.     

Environmental aspects on dyeing silk fabric with sticta coronata lichen using ultrasonic energy and mild mordants

Alluded to the current collaboration of the environmental technology, this article focused on the ultrasonic efficiency for dyeing silk fabric with sticta coronata lichen in the presence of alum and catechu mild mordants. The spectrophotometer studies on the dye uptake and fixation have been demonstrated, as well as, the influence of mordants and their combination on the colorimetric properties and light fastness. The results indicated that sticta coronata dye had a good substantively to silk fabric with brilliant lilac color. The pre-mordanting process exhibited a significant effect on the color strength, hue, and light fastness depending on the mordant type and concentration. The use of ultrasonic energy is found to have a significant improvement in the dye uptake representing the sonication efficiency in textile dyeing.