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Demand for textiles is increasing owing to human population growth, social competition, and fashion trends. This growth in demand is met at the cost of contamination of tons of fresh water with dye. In this study, microwave irradiation was used in dyeing of textiles as a method of minimizing this environmental threat. The microwave works through dielectric heating and realizes its effect on different dye structures. Dyeing was performed on six different reactive red dyes based on an H-acid coupling component with dissimilar substituents. UV–visible spectroscopy measurements revealed that auxochromes do not impart color to the dyes, but still have a great impact on color depth and hue. The zeta potential and temperature rise per minute under microwave irradiation were both affected by changes in the dye concentration and structure. The dyeing of cotton samples was performed by the exhaust microwave dyeing technique with an optimized recipe and conventional dyeing with a standard recipe for comparison. The color strength values obtained from the experiments revealed that the microwave technique provides better results by consuming 86.67% less salt with a lower liquor volume. The exhaustion and fixation values further confirmed this assessment. The color fastness against basic conditions was similar with both techniques; hence, the microwave can be considered to be a better technique in all aspects. Furthermore, the dye D195 was found to be more effective in achieving higher color depths with a less concentrated effluent indicating that the synthesis of high-performance dyes requires care in the selection of substituents. [ABSTRACT FROM AUTHOR]

The principal goal of this research revolves around imparting antimicrobial activities on printed cotton fabric utilizing silver nanoparticles. Two colorants, dyes, and pigments are used for printing of 100% scoured and bleached cotton, fabric, and both fabrics are assessed to get antimicrobial activity of printed cloth. Screen-printing techniques are used here to apply the pigment and reactive dye onto the fabric. The outcomes of the study reflect that the addition of silver nanoparticles to the reactive dye-printed and pigment-printed fabric significantly decreases bacterial growth up to 99.99%. In addition, Silver nanoparticles increase color intensity by around 25% in pigment printing, however, reduce it in reactive printing. Both methods enhance color fastness by increasing resistance to fading, staining, and rubbing. The scanning electron microscopy (SEM) analysis reveals that the print paste and sodium alginate have an impact on the distribution of nanoparticles. Through X-ray diffraction (XRD), it has been determined that the sample maintains a crystalline form and an average size of 29.185 nm of silver nanoparticles. Fourier Transform Infrared Spectroscopy (FTIR) analysis indicates no notable molecular-level alterations. [ABSTRACT FROM AUTHOR]

Dopamine (DA) can undergo complex oxidative self-polymerization to modify the surface properties of cotton fabrics; however, the disordered polymerization of dopamine to polydopamine (PDA) results in poor colorfastness and limits the application of DA to textile fibers. To ensure the ordered polymerization of DA and the growth of PDA and to obtain good colorfastness and depth in the PDA-modified cotton, we used the hot pad-batch (HPB) dyeing method for DA and Reactive Red 239 (RR-239), along with the action of the fabrics squeezing each other. We compared the differences in colorfastness caused by the disordered and ordered polymerization of DA and aluminum ions. We studied the effect of sodium carbonate, DA, and RR-239 concentration on the K/S values of the cotton fabric. We also analyzed the dyeing mechanism of PDA/RR-239 for cotton fibers and the effect of the aluminum ions therein via attenuated total reflection–Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) and determined the UV resistance, mechanical properties, and thermal properties of the cotton fabric. HPB dyeing produced better colorfastness than exhaustive dyeing with a co-bath of DA/RR-239 and enabled ordered polymerization of PDA on the fibers. HPB dyeing accelerated the formation of PDA in the presence of a small amount of aluminum salt. Thus, HPB dyeing is suitable for the modification of cotton fabric with DA and reactive dyes because it is a short dyeing process that can improve the washing and rubbing colorfastness to 4 and 3–4, respectively. [ABSTRACT FROM AUTHOR]

Wastewater containing reactive textile dyes constitutes a crucial environmental problem as they are permanent and dangerous. The electro-Fenton (EF) method is promising as an effective technique for degrading organic materials such as dyestuffs. In this study, the optimization of influential variables in removing reactive yellow 145 azo textile dye by EF was investigated using response surface methodology (RSM). Central composite design was used to study the combined effects of critical parameters such as voltage (2.5–12.5 V), H2O2 addition (0.1–1.3 mL), pH (1.75–4.75), electrode spacing (0.25–3.25 cm), and treatment time (25–85 min). The optimum values of the variables to ensure the highest dye removal efficiency (approx. 93%) with the lowest energy consumption (approx. 3.4 Wh/L) were approximately 9.4 V voltage, pH 3.7, 2.5 cm electrode spacing, 1 mL H2O2 addition, and a 40-min treatment time. ANOVA analysis of the predicted quadratic polynomial model showed a regression coefficient value of approximately 0.97 for both objective functions; this highlights the model's applicability for navigating the design space. Simultaneous optimization of process parameters using RSM was achieved with a few experiments. [ABSTRACT FROM AUTHOR]

In this research, low-priced bio-chars produced from biomass waste (fiddle-leaf fig seed) via physical and chemical activation processes were applied for selective removals of iodine and reactive dyes. The adsorption natures and capabilities were systematically considered from isotherms, kinetic and thermodynamic parameters. As achieved results, activated bio-char (ABC) prepared via phosphoric activation and carbonization at 400 °C for 2 h presented good capabilities for adsorptions of iodine (qmax = 420.47 mg/g) and reactive red 22 (RR22, qmax = 15.17 mg/g). The fast adsorption natures of iodine and RR22 using each adsorbent exhibited monolayer physisorption, which were identified by Langmuir, Dubinin–Radushkevich, Redlich–Peterson, Toth and pseudo-second order, while intra-particle diffusion with 2 steps could be obtained from Weber–Morris model. Thermodynamic nature also displayed that iodine and reactive dye adsorption procedures were endothermic and spontaneous styles, supporting by standard enthalpy/entropy/Gibbs free energy at temperature range about 303–328 K. Moreover, the capability for selective removal of wastewater models (mixed dyes) over all adsorbents was in order of reactive blue 19 (RB19) > RR22 > reactive yellow 3 (RY3). This work methodically focused on adsorption manners of dye molecules using low-priced bio-char and gave possible/green way for wastewater treatment under practical process. [ABSTRACT FROM AUTHOR]

Background: Reactive Red (RR) 141 dye is widely used in various industrial applications, but its environmental impact remains a growing concern. In this study, the phytotoxic and genotoxic effects of RR 141 dye on mung bean seedlings (Vigna radiata (L.) Wilczek) were investigated, serving as a model for potential harm to plant systems. Methods and results: Short-term (14 days) and long-term (60 days) experiments in paddy soil pot culture exposed mung bean seedlings to RR 141 dye. The dye delayed germination and hindered growth, significantly reducing germination percentage and seedling vigor index (SVI) at concentrations of 50 and 100 ml/L. In short-term exposure, plumule and radical lengths dose-dependently decreased, while long-term exposure affected plant length and grain weight, leaving pod-related parameters unaffected. To evaluate genotoxicity, high annealing temperature-random amplified polymorphic DNA (HAT-RAPD) analysis was employed with five RAPD primers having 58–75% GC content. It detected polymorphic band patterns, generating 116 bands (433 to 2857 bp) in plant leaves exposed to the dye. Polymorphisms indicated the appearance/disappearance of DNA bands in both concentrations, with decreased genomic template stability (GTS) values suggesting DNA damage and mutation. Conclusion: These findings demonstrate that RR 141 dye has a significant impact on genomic template stability (GTS) and exhibits phytotoxic and genotoxic responses in mung bean seedlings. This research underscores the potential of RR 141 dye to act as a harmful agent within plant model systems, highlighting the need for further assessment of its environmental implications. [ABSTRACT FROM AUTHOR]

Reactive dyes exhibit suitable opto-electronic properties, making them promising for dye-sensitized solar cell (DSSC) applications. The present study uses reactive orange 16 dye to design an efficient dye sensitizer for DSSC application using a donor–π–acceptor concept. The sensitizer structures and their electronic and optical properties were investigated using density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The molecular electrostatic potential maps, HOMO–LUMO distributions, and density of states plots were obtained for the optimized geometry. The analysis showed that the electronic properties of reactive orange 16 are enhanced due to the π-linkage, responsible for extending the conjugation length of the system. The TD-DFT calculations showed a bathochromic shift in the absorption spectra due to the introduction of the π-linker. The shift confirmed the conjugation's role in enhancing the sensitizers' electronic properties. The transitions were π → π* and n → π*, and the transition with maximum oscillator strength was assigned to the H → L excitation. The study showed that donor–π–acceptor concept-based sensitizers derived from reactive dyes favor DSSC applications. Hence, this study's findings could be used to design and develop more efficient dye sensitizers based on reactive dyes. [ABSTRACT FROM AUTHOR]

The use of low-cost adsorbent such as bottom ash has been investigated as a replacement for the current expensive materials for removal dyes from aqueous solution. The adsorbent was obtained from incinerated hospital waste (Mascara, Algeria). The prepared adsorbent was characterized by X-fluorescence, XRD, scanning electron microscopy, specific surface area (BET method) and pH(PZC). The results indicated that the material consisted of silica, carbonates and sodium chloride. The surface area and PZC were 1.29 m2/g and 8.9, respectively. The solid was applied for the removal of synthetic dyes namely Disperse Yellow 3 and Reactive Brillant Blue at various contact time, pH values and solution temperatures. The optimum pH and equilibrium time were 8.3 and 60 min, respectively. The dyes were adsorbed in single and binary solution. The adsorption isotherms show that the reactive dye was better adsorbed (269.36 mg/g) than the dispersive dye (120.64 mg/g). The adsorbed amounts of the dyes onto bottom ash were not affected by the type of system. The adsorption data were fitted with the linear forms of the Langmuir, Freundlich and Dubinin–Radushkevich models. Overall, the Langmuir isotherm showed a better fitting for all adsorptions under investigation in terms of correlation coefficient. Among the kinetic models tested, the adsorption reaction follows the pseudo-second-order kinetic controlled by intra-particle diffusion. In the both systems, the free energy and enthalpy changes obtained revealed that the process was spontaneous and endothermic. The positive entropy change confirms the enhancement of disorder near interface liquid/solid. [ABSTRACT FROM AUTHOR]

A detailed study was carried out to compare the removal of Reactive Blue 221 and Red X-5GN dyes using raw Helianthus Annuus L. seed shell as a natural adsorbent. There is no study in the literature for comparing the treatment of these anionic and cationic dyes using the current seed shell in raw form. Bringing a natural waste to the economy that can compete with adsorbents such as activated carbon commercially used in dye removal, will offer important advantages. The variation of initial pH value, shell dosage, contact time and, initial dye concentration was investigated. Reactive Blue 221 was successfully removed at pH 2 with a treatment efficiency of above 90%, while Red X-5GN was treated at pH 4 with a removal efficiency of 97%. Appropriate adsorbent dosages were 4 and 10 g/L for Reactive Blue 221 and Red X-5GN, respectively. Adsorption data of two dyes fitted very well to the pseudo-second-order reaction model with R2 values of 0.979–0.999. The data were best represented by the Langmuir model for Reactive Blue 221 with an R2 of 0.986. Freundlich isotherm was the most suited model for adsorption of Red X-5GN dye with an R2 of 0.996. The maximum uptake capacities were found to be 27.40 mg/g for Red X-5GN and 30.58 mg/g for Reactive Blue 221. The results showed that the conditions of adsorption for each dye can be significantly different. Besides, the potential of this seed shell as an eco-friendly and low-cost adsorbent was exhibited with perfect treatment results. [ABSTRACT FROM AUTHOR]

Textile wastewater treatment is a critical issue due to its high volume and pollution potential. This study investigates the photocatalytic degradation of red and green active dyes using a newly synthesized ZnO − TiO2 nano-photocatalyst doped with iron ions. The nano-photocatalyst is prepared through a green method using bitter olive seeds and a sol-gel method for doping iron ions. The XRD, FE-SEM, TEM, BET, and EDX characterizations show that the nano-photocatalyst is successful with a particle size of 50 nm and a specific surface area of 157.9 m2 g−1. Response surface methodology and central composite design are used to optimize the photocatalytic degradation of reactive dyes in synthetic and industrial wastewater. The optimal conditions were found to be initial dye concentration of 10 mg L−1, nano-photocatalyst dose of 0.5 mg L−1, contact time of 85 min, and pH of 6. Semi-industrial scale experiments show that the system is effective under both UV and visible radiation with removal efficiencies of more than 75% and 20%, respectively. The novel synthesis method and the high performance of the ZnO − TiO2 nano-photocatalyst doped with iron ions demonstrate the potential for practical application in the treatment of textile wastewater. [ABSTRACT FROM AUTHOR]

Malachite green (MG) is an organic dye and belongs to triphenylmethane category which is more harmful and toxic carcinogenic compound. In conventional methods for dye treatment, many metal ions and harmful chemicals were used. But in our study, we have proposed completely an eco-friendly method for dye degradation using carbon quantum dots (CQDs) from Spirulina platensis which is purely a natural and novel source of carbon-rich matter. The synthesized CQDs were characterized by TEM, SEM, particle size analyzer and fluorescence spectrophotometer. Sunlight promotes the photocatalytic activity of CQDs and degraded metabolites were analyzed by Gas chromatography–Mass spectrometry (GC–MS). Additionally, small quantity of synthesized CQDs acted as an efficient photocatalyst against 25 ppm concentration of MG dye and degradation was occurred within 3 h. 71% of BOD, 71.6% of COD and 78% of TOC were reduced by charcoal and it also helps to remove the CQDs from treated water by improving the quality of treated water with corresponding optical and physicochemical parameters. Based on the results of MG dye degradation, we have successfully done preliminary work for reactive blue MR and textile effluent degradation. A significant recycling process for degraded water was studied using phytotoxicity test and to prove that it does not possess any hazardous matter. [ABSTRACT FROM AUTHOR]

In this work, we study a unique phenomenon, which is the formation of surface plasmons on the surface of woven cotton fabrics dyed with reactive red dye and the effect of dye concentration on the surface plasmonicactivity. The results show that a peak was observed in the optical reflectivity spectra, which is an extension of the plasma edge. We called it the plasma peak. It represents the growth and decay phases of the plasmonic activity. Furthermore, the effect of dye concentration on both the plasma edge and the main characteristics of the plasma peak (position, spectral width, and intensity) is investigated. On the other hand, the dye concentration that results in the highest optical activity of surface plasmons was recorded (c = 2%). [ABSTRACT FROM AUTHOR]

In this study, low-cost adsorbent was easily prepared from Ficus lyrata seed (FS) or lignocellulosic waste, and utilized for the efficient removals of iodine and reactive dye molecules. The lignocellulosic powder was easily treated using acid–base chemicals such as HNO3 and KOH. The surface areas, porosities and morphologies of as-prepared adsorbent were analyzed by methylene blue adsorption method along with Langmuir calculation model. As obtained, rapid/multilayer-physisorption behaviors were interestingly found via Freundlich, Dubinin–Radushkevich, Temkin, pseudo-second-order and Weber–Morris models. The maximum capacities for iodine and reactive blue 19 molecules were found to be 340.00 (FS-Untreated) and 13.08 (FS-Treated by HNO3) mg/g, respectively. The highest percentage removals of selected reactive dyes from synthetic wastewater using FS-Treated by HNO3 were 58.30, 31.47 and 18.91% for reactive blue 19, reactive yellow 3 and reactive red 22, respectively, while 87.30% of iodine was removed using FS-Untreated. The endothermic and spontaneous adsorption of iodine and selected reactive dye molecules were verified under thermodynamic process. This research systematically studied on adsorption behaviors of iodine and reactive dye molecules, and provided high possibility to be truly applied in practical process for wastewater treatment. [ABSTRACT FROM AUTHOR]

This study aimed to synthesize a new bimetallic Fenton catalyst using Nb2O5 as the support for the active metal species of copper and iron. The coprecipitation method was used to prepare the catalyst, characterized by several technical means. The efficiency of the material was evaluated in batch mode in the degradation of a reactive blue 250 textile dye in aqueous media, with the study of the critical variables for the process. The catalyst employed resulted in 80% decolorization of the RB dye under the experimental conditions of pH 3, [Catalyst]0 = 1.0 g L−1, [H2O2]0 = 200 mg L−1, [RB]0 = 10 mg L−1. It proved to be very active under natural sunlight in the photo-Fenton system. It was possible to regenerate it and use it in five Fenton reaction cycles, demonstrating its stability and the quality of niobium as support.Please confirm if all the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Also, kindly confirm the details in the metadata are correct.The names are correct. [ABSTRACT FROM AUTHOR]

In traditional water-based dyeing system, a low fixation of reactive dye requires six to ten times washing after dyeing, which consumes a lot of water and results in huge dyeing effluent. To alleviate this issue, the development of a sustainable dyeing technology of cotton textile is essential. In the present investigation, silicone non-aqueous medium was employed to improve the fixation of dye with a pad-dyeing process under the optimized dyeing parameters. The appropriate washing-free dyeing conditions were recommended as follows: the padded fabric was placed at 105 °C for 15–30 s to complete pre-drying to decrease the water content rapidly, and then fixed in non-aqueous medium for 80–90 s at 95 °C. After dyeing, the dyed fabric was treated with 30 g/l fixing agent through pre-dried at 80 °C and baked at 160 °C. The results indicated that the final fixation of dye was above 95 %, and the dry rubbing fastness of dyed cotton fabric can reach grade 5. Moreover, the wet rubbing fastness and washing fastness of dyed cotton fabric can reach grade 3–4 and 4, respectively. Therefore, it can obtain the washing-free dyeing of cotton fabric with reactive dye. If the washing procedure was omitted in the industrial application, the environmental cost of cotton dyeing would be greatly decreased. This method provides a substantial reduction in wastewater effluent, which will be considerably potential for industrial application. [ABSTRACT FROM AUTHOR]

Blue, red and yellow chitin nanofibers were obtained using reactive dyes. Since the chitin nanofibers and the dye are covalently bonded, they are resistant to hot water and detergents. Since the dyed chitin nanofibers can be mixed at an arbitrary ratio, purple, orange, and green nanofibers corresponding to the mixed colors could be obtained. The dyed chitin nanofibers were evaluated by the reflection spectrum and the color space (L*a*b*). From the viewpoint of reaction yield and color properties, the appropriate ratio of the reactive dye to chitin was 5% at the maximum. The morphology of chitin nanofibers was maintained even after the introduction of the reactive dye. A resin combined with dyed chitin nanofibers was prepared. By combining with nanofibers, it may be possible to give color and improve mechanical strength to resin while maintaining the transparency of the resin to some extent. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation is a promising alternative for the degradation of reactive dyestuffs in residual dyeing liquid, which contains organic dyes, as well as salts such as sodium chloride and sodium sulfate. In this work, three kinds of salts, Na2SO4, NaCl and FeSO4, were selected to study the influence of electrolytes on the electrochemical oxidation of recalcitrant reactive red X-3B, using graphite cathode and dimensionally stable anode or graphite anode. The removals of color and chemical oxygen demand have been evaluated. Color removals were 99.97% and 99.84% with graphite anode and dimensionally stable anode in Na2SO4 and NaCl electrolyte. The corresponding chemical oxygen demand removals were 93.60% and 100%. In contrast, the maximum color and chemical oxygen demand removals were 97.32% and 68.76% in FeSO4 electrolyte. It was found that a combination of NaCl and FeSO4 achieved complete oxygen demand removal for both graphite anode and dimensionally stable anode. During the electrochemical oxidation process, anode and electrolyte exhibited a great effect on pH variations. Based on the cyclic voltammetry and active oxidative species investigations, the oxidation of reactive red X-3B was attributed to indirect oxidation of active chlorine and reactive oxygen species. [ABSTRACT FROM AUTHOR]

The dyeing and color fixation properties of reactive dyes on cotton woven fabrics have been systematically studied using reverse micelle with biodegradable alkyl polyglucoside (APG)-based non-ionic surfactant as building blocks in cyclosiloxane-based solvent under one-bath one-step approach. Reactive dyes were solubilized in the interior region of the reverse micelle under optimized process conditions as indicated by the color strength. Assessment of the color strength and fastness properties of cotton fabrics in reverse micellar dyeing was conducted and compared with aqueous dyeing. It was found that fluoropyrimidine reactive group of Levafix CA Red dyes encapsulated in APG-based reverse micelle exhibited higher color yield on cotton fabric compared to vinylsulfone group of both Levafix CA yellow and blue dyes. The results also represent that reactivity of the functional group combination of heterofunctional dyes influences color fixation on cellulosic surface in terms of color strength (K/S sum). [ABSTRACT FROM AUTHOR]

Polyvinylamine (PVAm) was investigated as a pretreatment auxiliary for salt-free reactive dyeing of calcium alginate fibers in this study. The effects of pretreatment conditions and dyeing conditions on the dye exhaustion (E%) were studied by using six reactive dyes. Relatively high E% of 91–98% and 61–80% were obtained by using three monochlorotriazine/sulfatoethylsulfone reactive dyes and three dichloro-s-triazine reactive dyes, respectively. The dyed fibers were able to maintain high color fastness and tensile strength. Adsorption isotherm of reactive dyeing and XPS analysis were also applied to investigate the mechanism of multi-interactions among reactive dyes, PVAm, and calcium alginate fiber. It was concluded that PVAm was an effective pretreatment auxiliary for salt-free dyeing of alginate fibers with reactive dyes. [ABSTRACT FROM AUTHOR]

The colour quality assessment of reverse micelle-based (in octane or nonane medium) and conventional water-based dyed wool knitted fabric has been investigated using computer colour matching (CCM) approach. Both water-based and non-aqueous based dyeing methods exhibited no chromatic shift from the reflectance curves and established good linearity in the construction of calibration curves. The linearity of both calibration curves in terms of R2 value played a critical role in CCM. The colour yield obtained from reverse micellar dyed fabric samples was higher than the colour yield values from wool knitted fabrics dyed in water bath under different dye percentages. The CCM predicted concentrations were in good agreement to theoretical concentrations for both dyeing systems. To conclude, the results showed that reverse micellar dyeing in octane and nonane is capable of generating reliable colour recipes. The relative unlevelness indices (RUI) obtained from dyed wool knitted fabrics using reverse micellar approach reveal good to excellent levelness, which fulfills the requirements of the textile processing industry. TEM picture illustrated that reverse micelles are in nano-scale and this could enhance the dyeing effect of wool with reactive dyes. [ABSTRACT FROM AUTHOR]

A new dye intermediate and novel reactive dyes containing both azo and benzsulfonamide auxochromic groups were synthesized. Their structures were characterized by 1H-NMR, 13C-NMR, MS, IR, and UV-Vis spectral analysis. The synthesized dyes were applied to dyeing of cotton fabrics and their dyeing parameters were assessed. The new dyes exhibited improved substantivity and fixation property on cotton fabrics compared with the dye C.I. Reactive Black 5 (RB5). The maximum exhaustion and total fixation values of the reactive dyes appeared when 2 % owf of the dye concentration was used. The wash fastness and rub fastness of the new dyes reached up to 4 grade and 4–5 grade, respectively. In addition, they showed excellent fastness to light. These new dyes seem to be promising candidates for application to dyeing of cotton fibers. [ABSTRACT FROM AUTHOR]

Comparative results of color removal performances of Reactive Blue 198 (RB198), Reactive Yellow (RY145) and Reactive Blue 19 (RB19) by electrocoagulation process are presented. Our primary objective was to investigate whether the dye molecular weight affects color removal performance. Dye removal costs of each dye were calculated and compared. Experiments were performed at current densities of 1.04, 2.08, 4.17 and 10.42 A/m2 in electrocoagulation (EC) reactor with aluminum electrodes connected parallel monopolar configuration. Laboratory-scale experiments were run in batch mode with 0.5 L synthetic dye solution volume and 50 mg/L initial dye concentration. Results showed that the color removal efficiencies were directly influenced by the molecular weight of the dyes. The color removal efficiency of the dye with the greatest molecular weight (RB198) was the highest, whereas the color removal efficiency of the dye with the smallest molecular weight (RB19) was the lowest. Moreover, results indicated that the operating cost of RB198 was significantly lower (2.91 $ per kg dye removed) than RY145 (6.61 $ per kg dye removed) and RB19 ($6.72 per kg dye removed) at a current density of 4.17 A/m2. [ABSTRACT FROM AUTHOR]

The agricultural waste of orange peels (OPs) was utilized as a cheap biosorbent and then tested for its ability to treat the reactive red (RR) dye wastewater. Several experiments were done to get the equilibrium isotherm and kinetic-relevant data. In addition, several experimental factors such as solution pH, temperature, contact time, and initial RR dye concentration were studied, in light of their impact on the biosorption process. The utilized isotherm and kinetic models were evaluated by using the chi-square test and coefficient of determination parameters for their representation of real data. In addition, the obtained data of their biosorption capacities, at different conditions, were modeled by the artificial neural network (ANN) approach. The results of the isotherm study revealed that the experimental data can be best accounted by both the Langmuir and Temkin models, demonstrating that the RR molecules were sorbed to two or more different types of biosorption sites of OP. The kinetic study for determining the characteristics of the rate of diffusion demonstrated that the intraparticle diffusion process was not the sole rate-limiting step in the biosorption of the RR dye-OP couple. Furthermore, the biosorption process was chemisorption in nature, as the pseudo-second-order reaction proved to be the best representative model for the kinetic data. The outcome of modeling also assumed that using the ANN tool was useful to reproduce the data again and foretell the manner in which biosorption behaved. According to the results of the Langmuir model, it was found that the maximum OP uptake for the biosorption of the RR dye was up to 82 mg/g, observed at optimized values of the experimental parameters. Such prior results highlight that OP is an effective agent of biosorption in the elimination of RR dyes from polluted solutions, moreover, in a cost-effective manner. [ABSTRACT FROM AUTHOR]

Traditional dyeing usually consumes a large amount of water and chemicals, thus causing environmental problems. To alleviate these problems, non-aqueous dyeing technology appears as an alternative for improving dye fixation and reducing effluent discharge. Here we used silicone non-aqueous medium to dye a wool fabric. Continuous pad dyeing with reactive dyes was investigated. We optimized the type of penetrating agent, padder pressure and concentration of dye. Results show that the fixation and exhaustion reach 88% and 98%, respectively, which are higher than for water-based dyed samples. The rubbing fastness of the dyed wool fabric is improved 1–2 times, and the consumption of dye is reduced by 20% by comparison with acid or reactive exhaust dyeing. Other advantages include continuous salt-free dyeing, washing and drying; saving water and less water pollution. [ABSTRACT FROM AUTHOR]

Traditional dyeing of cotton fabrics with reactive dyes has produced many environmental problems. Therefore, it is important to investigate the relationship between dye molecular structures and dyeing properties for cleaner procedures. Here, the properties of five azo-based reactive dyes with different substituents and reactive groups were studied. The dyes had similar molecular shapes, sizes, and chromophore structures. Differences were in the aromatic rings, the number of sulfonate groups, and the position of vinyl sulfonate on the benzene ring. The dye substantivity (S%), exhaustion (E%), reactivity (R%), fixation (F%), color strength, salt effects, alkali effects, and color fastness were investigated and analyzed. Different substituents on the dyes had a little effect on the ultraviolet-visible absorption maximum wavelength. In addition, the requirements of salt and alkali to produce the maximum color strength varied for different dye structures. The dye containing a naphthalene ring, three sulfonate groups, and a vinyl sulfonate at the para-position of the benzene ring produced the highest color strength and fixation values. Color fastness was almost the same for each dyed sample, except for the wet-rubbing fastness. The results should be useful for developing new dyes and environmentally friendly dyeing techniques. [ABSTRACT FROM AUTHOR]

Decreasing the temperature for dyeing wool fiber with reactive dye using a laboratory based ultrasonic machine was investigated as a way to obtain good quality dyed samples. Ultrasonic irradiation was used to reduce dyeing time and temperature whilst increasing dye migration and fastness. The ultrasonic machine was set at a 40 kHz frequency level, with effective power of 130 W and heating power of 350 W to carry out the dyeing process of the wool fiber within the temperature range 60-80 °C. The dyeing processes used both ultrasonic dyeing and without ultrasonic dyeing to obtain the laboratory results. At every dyeing stage from 60 °C to 80 °C, the exhaustion rate of dyeing was measured. Ultrasonic dyeing yielded better results compared to without ultrasonic dyeing. The diffusion coefficient, partition ratio, and standard affinity increased with the increased dyeing temperature and the use of an ultrasonic bath. The efficiency of ultrasonic dyeing was measured and the absorption rate constant was at least 55 % greater than without ultrasonic dyeing at every dyeing temperature i.e. 60 °C, 70 °C, and 80 °C. The color fastness to washing and rubbing was better for samples dyed with ultrasonic dyeing. Scanning electron microscopy (SEM) was used to measure the surface changes of the fiber. SEM analysis showed no evidence of scale damage on the wool fiber surface. [ABSTRACT FROM AUTHOR]

In the present work, an ultrasound-assisted reverse-precipitation method was applied as a new approach for the synthesis of CuxO/Fe2O3/MoC. In the sonication method, a bath type sonicator as a simple, cost-effective, and low intensity sonicator was used. To determine the influence of ultrasonic waves on the morphology and application of nano-hybrid as nano-sorbent, it was also synthesized using the reverse precipitation method. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), transmission electron microscopy (TEM), Zeta-potential measurement, and vibrating sample magnetometer (VSM) techniques. The XRD analysis confirmed that the sono-synthesized sample has higher crystallinity than the conventional one and CuO/Cu2O/MoC/Fe2O3 phase was obtained under ultrasound. According to the TEM and FESEM, sono-synthesized nanoparticles were rod-like with a width and length of 3 nm and 40 nm, respectively. Also, a well-dispersed shape and uniform morphology of nanoparticles were obtained using sonication. In comparison with the conventional nano-hybrid, this structure results in more void and accessible sites for adsorption of pollutants. The efficiency of resulting nanoparticles in adsorption of reactive dyes as a model of the pollutant was evaluated by sorption and sono-sorption processes. The sono-synthesized sample removed the pollutants more efficient than the conventional sample. The removal efficiencies were about 99% for the removal of reactive dyes using the sono-synthesized sample and sono-sorption method. Besides, determining factors including pH, pollutant concentration, temperature, and contact time were optimized in the sono-sorption and sorption processes. A colorimetric method based on RGB value was used to determine dye concentration in aqueous media. The images were taken by a smartphone and analyzed by ImageJ software. The accuracy of RGB results was confirmed by a UV–Vis spectrophotometer. [ABSTRACT FROM AUTHOR]

A real anhydrous liquid ammonia dyeing technique was established that included a cationic modification of the ramie fiber in liquid ammonia, dyeing of the cationic ramie fiber in liquid ammonia, drying to fix the cationic agents and the reactive dyes in the ramie fiber, and washing the cationic ramie fiber and the dyed cationic ramie fiber with liquid ammonia to remove the unfixed chemicals. The zeta potential of the cationic ramie fiber indicated that the cationic groups were successfully grafted on the fiber. The dye exhaustion percentage and the fixation rate improved. The dyed cationic ramie fiber had excellent wash fastness, satisfactory color uniformity, and acceptable breaking strength and breaking elongation rate for spinning. High performance liquid chromatography analysis was used to measure the stability of the dye's reactive group during the liquid ammonia dyeing and drying. The results showed that the dichlorotriazinyl group was unstable, while the monochlorotriazinyl and vinyl sulfone groups were stable during the liquid ammonia dyeing. The monochlorotriazinyl group and vinyl sulfone groups changed to their non reactive derivatives after drying. [ABSTRACT FROM AUTHOR]

Reactive dyestuff is commonly used in the textile industry. Reactive dyebath wastewater (RDW) was treated with a batch, monopolar, parallel lab scale electrocoagulation process (EC) having 0.042 m2 effective electrode area. The effects of process parameters, such as initial pH, current density and electrolysis period on COD and color removal efficiency, were investigated by using response surface methodology (RSM). At the optimal conditions, 85.8% color and 76.9% COD removal were obtained with 1.84 €/m3 operating cost for Al electrode, while 92.0% decolorization and 80.9% COD removal were obtained with 1.56 €/m3 operating cost for an iron electrode. The iron electrode was found superior to aluminum as a sacrificial anode material in terms of COD and color removal with low cost. The cost of electrical energy, electrode, and chemical consumptions for electrocoagulation were considered to find an optimum and feasible solution. As a result, the operating cost consists of approximately 2% for energy, 28% for electrode and 70% for chemical consumption for both electrodes. Based upon the data, it is clearly seen that operating cost covers mostly for HCI to adjust pH due to the high pH and alkalinity of RDW, which was neglected in many studies. The first-order reaction kinetics with a higher slope for the color were well fitted, resulting in faster color removal than that of COD for both electrodes. [ABSTRACT FROM AUTHOR]

The Reactive Black 5 and Reactive Red dyestuffs have been synthesized in the laboratory. The synthesis was obtained by diazotization of 1-amino-phenyl-4-beta hydroxyethyl sulfone sulfate ester and coupling with 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid (H-acid) (mole ratio 2:1) (Reactive Black 5Na) and (mole ratio 1:1) (Reactive Red Na). The dye was purified-concentrated by ultrafiltration technology and the permeate (waste) was used as dye bath in the exhaustion of cotton and polyamide with the sodium salt of Reactive Black 5 (RB5Na) and the sodium salt of Reactive Red (RRNa). The same dyeing was also made with fresh water as dye bath. Fastness properties were also measured in both cases and the results were compared. Color measurement results of the dyeings were almost the same when the waste as dye bath was used. [ABSTRACT FROM AUTHOR]

The present paper investigates the effects of breed and age on the dye fixation on wool using a reactive dye. It also examines the optimization of the dyeing process realized using the response surface methodology. The dyeing step was carried out on raw wool using the bichromatic blue dye reagent Cibacron P-3R (C.I. Reactive Blue 49). The factors affecting the dyeing process, such as ammonia concentration, temperature, and the duration of the dyeing time, were studied using the response surface methodology. The performance of this dyeing process was evaluated by measuring the color yield (the dye fixation). The results have shown that the age and the breed of sheep have a significant effect (P <0.05 %) on the dye fixation rate. This can be attributed to the differences in the amino acids of wool. Additionally, it has been found that the youngest wool and the Sicilo-Sarde breed always yielded the best dye fixation while the oldest wool and the Fine Queue of west breed (QF) have the lowest dye fixation. Using the response surface methodology, this research has proved that the best dyeing quality for the QF is obtained by using an amount of ammonia of 20 ml, a dyeing duration of about 60 min, and a dyeing temperature of about 100 °C. [ABSTRACT FROM AUTHOR]

This study was undertaken to evaluate the adsorption of Reactive Black 5 dye (RB5), in aqueous solution, onto MCM-41 mesoporous silica nanoparticles (MSNs) functionalized with 3-aminopropyltriethoxysilane (APTES) by two methods: co-condensation and post-synthesis. The morphological and surface properties of both functionalized materials were compared by SEM, SAXS, N2 sorption and XPS characterization techniques. Sorption experiments were performed in order to determine the effect of pH, contact period and initial concentration of aqueous RB5 on the adsorption properties of bare- and both types of amino-MSNs. The results show that there exist morphological changes in the nanoparticles according to the type of functionalization synthesis, i.e. loss of hexagonal structure in co-condensation method and more density of amino groups on the surface of post-synthesis functionalized materials. The adsorption of RB5 on both type of materials is independent of the pH since they present adsorptions close to 100% in the evaluated pH range. The best fit of the data from adsorption kinetic studies is a pseudo-second-order model, being the material functionalized by the co-condensation method, which presents a higher adsorption rate because of its greater pore volume. The adsorption isotherms fitted well to the Langmuir model, with the amino-MSNs functionalized via the post-synthesis method presenting a higher capacity of adsorption, due to a greater density of amino groups on its surface, thereby facilitating their interaction with the RB5 molecules. Altogether, the results indicate that the type of functionalization synthesis affects the morphological characteristics of the nanoparticles and these, in turn, modify their adsorption properties. [ABSTRACT FROM AUTHOR]

Abstract Dyeing effluents have become a vital source of water pollution. Due to the xenobiotic properties and toxicity to all life forms including humans, removal of undesirable color and associated toxicity is crucial. In this study, five dye decolorizing bacteria were isolated from dyeing effluent using selective enrichment culture in Bushnell-Haas (BH) medium amended with co-substrate (i.e. glucose, yeast extract) and 100 mg L−1 of each commercially available reactive dyes viz. Novacron Orange FN-R, Novacron Brilliant Blue FN-R, Novacron Super Black G, Bezema Yellow S8-G and Bezema Red S2-B. The isolated bacteria were identified and assigned as Neisseria sp., Vibrio sp., Bacillus sp., Bacillus sp. and Aeromonas sp. based on their phenotypic (cultural, morphological, physiological and biochemical characteristic) observation. The dye decolorization efficiency was estimated spectrophotometrically up to 6 days of static incubation at 37 °C and observed that all of the isolates were unable to induce decolorization in absence of co-substrate. In case of monoculture, decolorization percentage varies from no visible decolorization (Bezema Red S2-B by Ek-5) to highest 90% decolorization (Novacron Brilliant Blue FN-R by Ek-13) whereas the decolorization percentage of bacterial consortium varies from 65% (Bezema Yellow S8-G) to 90% (Novacron Brilliant Blue FN-R and Novacron Super Black G). The study outlines the co-substrates mediated decolorization process where bacterial consortium proved as efficient dye decolorizer than that of the monocultures. This finding confers possibility of using novel microbial consortium for biological treatment of disreputable dyeing effluents. [ABSTRACT FROM AUTHOR]

The chemical recycling of cellulosic fibres may represent a next-generation fibre-fibre recycling system for cotton textiles, though remaining challenges include how to accommodate fibre blends, dyes, wrinkle-free finishes, and other impurities from finishing. These challenges may disrupt the regeneration process steps and reduce the fibre quality. This study examines the impact on regenerated viscose fibre properties of a novel alkaline/acid bleaching sequence to strip reactive dyes and dimethyloldihydroxyethyleneureas (DMDHEU) wrinkle-free finish from cotton textiles. Potentially, such a bleaching sequence could advantageously be integrated into the viscose process, reducing the costs and environmental impact of the product. The study investigates the spinning performance and mechanical properties (e.g., tenacity and elongation) of the regenerated viscose fibres. The alkaline/acid bleaching sequence was found to strip the reactive dye and DMDHEU wrinkle-free finish from the cotton fabric, so the resulting pulp could successfully be spun into viscose fibres, though the mechanical properties of these fibres were worse than those of commercial viscose fibres. This study finds that reactive dyes and DMDHEU wrinkle-free finish affect the viscose dope quality and the regeneration performance. The results might lead to progress in overcoming quality challenges in cellulosic chemical recycling. [ABSTRACT FROM AUTHOR]

Abstract: Anhydrous liquid ammonia was used as a solvent for the cationic modification of ramie fiber using 2, 3-epoxypropytrimethylammonium chloride (EPTAC). The processing parameters, including treatment temperature, treatment time, concentration of EPTAC, and concentration of NaOH were schematically investigated in order to control the properties of the fibers. The optimum parameters for cationic modification in liquid ammonia were analyzed through zeta potential measurement. The modified fibers were dyed in different conditions after modification, and the dyeing behaviors such as exhaustion and fixation properties were carefully examined. The modified fiber in liquid ammonia consisted of a higher number of cationic groups on the fibers compared to the fibers modified in water. The cationization reaction in liquid ammonia significantly decreased the crystallinity and the crystallite orientation of the resultant fibers. The decreased crystallinity slightly decreased the thermal resistance and tensile strength but increased the elongation ability of the fibers. The liquid ammonia cationic modification process turned the appearance of fibers from rough to smooth and lustrous due to swelling of fibers in the solvent. The exhaustion, fixation and wash fastness property of the fibers were improved after the cationic modification in liquid ammonia.Graphical Abstract: [ABSTRACT FROM AUTHOR]

The theme of present research demonstrates performance of copper (II) sulfate (CuSO4) as catalyst in thermolysis process to treat reactive black 5 (RB 5) dye. During thermolysis without presence of catalyst, heat was converted to thermal energy to break the enthalpy of chemical structure bonding and only 31.62% of color removal. With CuSO4 support as auxiliary agent, the thermally cleaved molecular structure was further destabilized and reacted with CuSO4. Copper ions functioned to delocalize the coordination of π of the lone paired electron in azo bond, C=C bond of the sp2 carbon to form C-C of the sp3 amorphous carbon in benzene and naphthalene. Further, the radicals of unpaired electrons were stabilized and RB 5 was thermally decomposed to methyl group. Zeta potential measurement was carried out to analyze the mechanism of RB 5 degradation and measurement at 0 mV verified the critical chemical concentration (CCC) (0.7 g/L copper (II) sulfate), as the maximum 92.30% color removal. The presence of copper (II) sulfate catalyst has remarkably increase the RB 5 dye degradation as the degradation rate constant without catalyst, k1 is 6.5224 whereas the degradation rate constant with catalyst, k2 is 25.6810. This revealed the correlation of conversion of thermal energy from heat to break the chemical bond strength, subsequent fragmentation of RB 5 dye molecular mediated by copper (II) sulfate catalyst. The novel framework on thermolysis degradation of molecular structure of RB 5 with respect to the bond enthalpy and interfacial intermediates decomposition with catalyst reaction were determined. [ABSTRACT FROM AUTHOR]

The washing efficiency of water, nonionic soap solution, reflux solution, pure liquid ammonia (99.99%), and solvated liquid ammonia was studied on dyed ramie yarns. The ramie yarn samples were dyed with a 2% on weight of fiber (o.w.f) shade with five types of reactive dye by the classical exhaustion method. The washing performances of these solvents were quantified by the dye removal rate, the color uniformity, and the color fastness properties (washing, rubbing, and lightness). Furthermore, the influence of these wash methods on the physical properties of the final yarn samples including shrinkage, tensile strength, and elongation was schematically examined. The results of these measurements revealed that the dye removal rates during the washing in pure liquid ammonia and solvated liquid ammonia were lower than the yarn washed in water, soap solutions, or reflux solutions. The color uniformity (expressed as the standard deviation of K/S values for all dyed ramie yarns) was within the acceptable limits with the satisfactory color fastness levels. The shrinkage values of yarns that were washed in the pure liquid ammonia and the solvated liquid ammonia were both similar (9.0%) and considerably higher than the samples washed in water (1.8%), soap solution (2.4%), or reflux solution (2.6%). The tensile strength and the elongation of the resultant yarns improved significantly when the samples washed in pure liquid ammonia. The yarns that were washed in the solvated liquid ammonia solutions had decreased tensile strength and elongation. The cause of the decrease was determined by the XRD measurements, which confirmed that the crystallinity, and the orientation of these fibers decreased dramatically after being washed in the ammonia system solutions. The samples that were washed in the liquid ammonia had a smoother surface morphology than the other washing processes. [ABSTRACT FROM AUTHOR]

The concept of third-hand cigarette smoke is a newly-emerging field of interest in public health. Release of second-hand smoke chemicals on the textile surface as a third-hand smoke to the surrounding environment is a malodorous release of hazardous chemicals to health. In this study, the influence of MCT-β-cyclodextrin treatments on not only the third-hand cigarette smoke odor release property but also on the mechanical and dyeing performances of cotton fabric was investigated. MCT-β-cyclodextrin treatments increased the stiffness and tensile strength of cotton fabric. The presence of MCT-β-cyclodextrin on cotton fabric did not significantly affect the dyeing properties and caused no profound effects on the obtained color strength levels on fabrics dyed with Drimarene reactive dyes. MCT-β-cyclodextrin treatment resulted in a significant reduction of the third-hand smoke odor release intensity from the smoke-contaminated cotton, for both dyed and undyed fabrics. The reactive dyes resulted in a positive influence on the third-hand smoke odor release intensity. MCT-β-cyclodextrin presence on the dyed fabric enabled a significant decrease in odor and produced a masking effect with an odor release reduction of up to 65.5%. Inclusion complex between the β-cyclodextrin rings and the volatile organic compounds of the cigarette smoke is believed to be a smoke odor chemical trapping mechanism. MCT-β-cyclodextrin treatment effectively masks chemical malodors from second-hand cigarette smoke and lessens the third-hand smoke odor chemical release onto cotton fabric. Therefore, MCT-β-cyclodextrin treatment may lessen the potential health hazards of third-hand smoke released from the contaminated textile surfaces. This is promising and encouraging for odor emission control and third-hand smoke release problems for smoke-exposed textile products. [ABSTRACT FROM AUTHOR]

Reactive dye is a popular dye for dyeing cotton fiber due to its very good color fastness which is explained by the formation of covalent bond between dye and fiber. In this study, practicality of reuse of reactive dye by compensating for the hydrolyzed part of the dye solution is examined. A monofunctional dye (vinyl sulfone type) was used and it was found that dyeing cotton fiber with reused dyebath is possible. Since bifunctional dye can improve the chance of dye-fiber bond formation, vinyl sulfone based bifunctional reactive dyes were also selected in this study. Three types of bifunctional dyes were used and they basically share the same vinyl sulfone group; other reactive groups are monochlorotriazine, dichlorotriazine and vinyl sulfone. Such dyes were chosen in order to compare their respective efficiencies under the effect of one common reactive group. The aim of this study was to compare the effect of hydrolyzed and unhydrolyzed proportions of mono-and bifunctional reactive dyes on cotton fiber and study the possibility and efficiency of the two different reuse dyebath systems. [ABSTRACT FROM AUTHOR]

In order to produce deep shades of colour, ramie fibre was subjected to pretreatment by cationization, caustic mercerization (slack and tension condition), and liquid ammonia mercerization. The untreated and pretreated samples were dyed with 0.5 to 7 % concentrations (on mass of fiber (o.m.f)) of Liyuansol Red FL-2BL reactive dye. The dyeing properties of dye exhaustion, fixation, colour uniformity, wash fastness, and rubbing fastness were investigated. The results indicated that these pretreatments improved dye exhaustion and fixation on ramie fibre, with no loss of fastness. For the untreated and treated substance, the amount of dye mass absorption increased linearly with increased dye o.m.f. Cationic treatment improved performance, with 89 % and 98 % for exhaustion and fixation, respectively, and the maximum K/ S values of all fibers receiving pretreatment. The colour uniformity was acceptable and similar for the untreated and treated ramie fibers, with the exception of cationic-treated fabric dyed at 7 % dye o.m.f that showed a high standard deviation value of colour uniformity. The Freundlich and Langmuir adsorption isotherm models were also used to study the adsorption of dye on ramie fibre; all of the adsorption processes fit the Freundlich model. [ABSTRACT FROM AUTHOR]

Cationization of cotton brings advantages in the reactive dyeing process, such as eliminating the use of electrolytes and increasing color yield. However, high dye strike rates caused by the electronic attractions between anionic dyes and cationized cotton may result in poor levelness of dyeing, especially for light shades. For some monochloritriazine-monochloritriazine homobifunctional reactive dyes, lowering dyeing temperature and controlling the addition of electrolytes can effectively control the dye strike rate and improve the levelness of dyed cationized cotton. However, for other reactive dyes, the use of effective leveling agents is necessary. In this study, a variety of anionic, cationic, and amphoteric leveling agents were applied to control the dye exhaustion process of three monochloritriazine-vinylsulphone heterobifunctional reactive dyes on the cotton fabric cationized using 3-chloro-2-hydroxypropyl trimethylammonium chloride. The leveling effect of adding dyes in portions was also evaluated and it was used in combination with leveling agents to further improve the levelness of dyeing. [ABSTRACT FROM AUTHOR]

A series of modified guar gums with s-triazine group (TSG) was successfully prepared using monochlorotriazine sulfanilic acid as modifier under certain conditions. The flowability, viscoelasticity, and thixotropy of TSG solutions were thoroughly studied through steady shear, dynamic strain sweep, and structural recovery tests. The results indicated that TSG exhibited better flowability, more viscous effects, and higher viscosity recoverability compared with guar gum (GG). The flow and viscous characteristics of TSG increased with increasing degree of modification. As thickeners in reactive printing of cotton, the paste add-on, color yield, and penetration of TSG were 54-80, 15-60, and 31-48% higher, respectively, compared with GG. TSG could obtain desirable large patterns with bright and even color as well as fine patterns with good outline sharpness, especially 0.4-1.0TSG. TSG has great potential as a substitute for sodium alginate in reactive printing of cotton. [ABSTRACT FROM AUTHOR]

Chemical cationization of cotton has been a subject of increased interest due to the ability of cationized cotton to attract negatively charged dyes, thus eliminating the use of electrolytes during dyeing and increasing color yield. However, electrostatic attractions between cationized cotton and anionic dyes also result in significantly increased dye strike rates, which may cause levelness problems, especially when light to medium shades are required. In this study, cotton fabric cationized using 3-chloro-2-hydroxypropyl trimethylammonium chloride was used to investigate the method for obtaining appropriate dye strike rate to produce a level reactive dyeing on cationized cotton. To effectively control the dyeing kinetics of reactive dyes on cationized cotton, real-time exhaustion of six commercially significant reactive dyes were monitored. The influence of temperature, dye structure, and addition of soda ash on dyeing kinetics and levelness of cationized cotton were evaluated. [ABSTRACT FROM AUTHOR]

Pollution due to heavy metals and dyes has become a major global environmental issue. Simultaneous removal of heavy metals and dyes from wastewater remains a major challenge. In this study, a zeolite supported nano-scale zero-valent iron (Z-nZVI) composite was innovatively used for the simultaneous removal of Cr(VI) and Reactive Black 5 from aqueous solution. Experiments were carried out at different pH values (2–8) and adsorbent dosages (0.2–1 g L−1). The maximum removal was found to be 99% for both Cr(VI) and Reactive Black 5 (RB5) at pH 3 with initial RB5 concentration 85 mg L−1, Cr(VI) concentration 23 mg L−1 and adsorbent dosage 1 g L−1. A Freundlich model showed a satisfactory fit to the equilibrium adsorption data of a Z-nZVI composite with a correlation coefficient R2 = 0.9790 for RB5 and R2 = 0.9726 for Cr(VI). The kinetics of adsorption followed a pseudo-first-order model. The results of the study indicated that a Z-nZVI composite could potentially be used for the simultaneous removal of metals and dyes from wastewater. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) was evaluated for its possibility as an immobilization matrix for the raw biomass of Corynebacterium glutamicum. Initially, different blending ratios of the raw biomass to PU weight were tested, and the ratio of 7: 3 was identified as the optimal condition. PU-immobilized biosorbent (PUIB) with a particle size ranging from 0.425 to 0.18mm was selected for the adsorption of Reactive Yellow 2 (RY2). The uptake of RY2 on the PUIB was favorable at acidic pH, especially below 3. According to the Langmuir model, the maximum RY2 uptakes were estimated to be 104.0, 93.3, and 87.3mg/g at pH 2, 3, and 4, respectively. The pseudo-first-order and pseudo-secondorder models were applied to fit the biosorption kinetic data; the latter model fitted the data well with a high coefficient of determination (R) and low average percentage error (ε) values. The RY2-sorbed PUIB was able to be regenerated and reused for five cycles of the adsorption and desorption processes. [ABSTRACT FROM AUTHOR]

The dyeability of cotton fabrics with reactive dye, in non-aqueous alkane medium of heptane and octane was investigated using a non-ionic surfactant reverse-micellar approach comprising of poly(ethylene glycol)-based surfactant. The reactive dye was satisfactorily encapsulated in the cavity of the reverse micelle under the optimised process parameters as measured by the colour yield. Dyeability of cotton fibre with reactive dye from the reverse micellar solution was improved even in the absence of electrolytes. Optimisation of dyeing and fixation process could be achieved in a one-bath reverse-micelle solution. Experimental results revealed that dyeability in the alkane-assisted dyeing process is better than that in conventional water-based dyeing without incorporation of electrolytes. The scanning electron microscopic images showed no obvious surface damage from heptane or octane but some microfibrils were noticed. [ABSTRACT FROM AUTHOR]

The assembling (self-association vs. aggregation or agglomeration) of highly polydispersed nanocelluloses (NCs) is a well-known but difficult to identify phenomena. In this research complementary analytical tools were applied for tracking and assessing this phenomena under different conditions (base vs. buffer) using both native and dye-labelled cellulose nanofibrils (CNFs) and cellulose nanocrystals. For this purpose, dichlorotriazine-type reactive blue 4 (RB4) dye was covalently (through alkyl-aryl ether bond) and regioselectively (to C6-OH groups) attached to the NC, being identified by ATR-FTIR and C CP/MAS solid-state NMR spectroscopies, and quantified by UV-Vis spectroscopy. The introduced RB4's anthraquinone (i.e. hydrophobic) moieties evoked aggregation of those CNFs being quantified from the shifting and broadening of size-distribution profiles within differential light scattering analysis and their ζ-potential reduction. In addition, their high polydispersity profiles was assessed by qualitatively supported differential centrifugal sedimentation, nanoparticle tracking analysis, and transmission electron microscopy. A desorption of chemically non-bonded, yet highly substantive (i.e. partially or fully hydrolysed), dye from both types of NCs was also identified by capillary electrophoresis, which simultaneously excluded the non-labelled fractions, thus obtaining free dye-absent NC dispersions. Finally, labelling extent-triggered separation within the RB4-labelled CNFs was identified by applying the micellar capillary electrophoresis, thus confirming the conformational changes affecting NCs' hydrodynamic (size) profiles. [ABSTRACT FROM AUTHOR]

The novel reactive photochromic spirooxazine dye containing a permanent chromophore and a reversible spirooxazine part was synthesized. The prepared dye was characterized by spectral analysis viz. FTIR, H-NMR, UV-Vis, mass spectroscopy, and elemental analysis. The results obtained from spectral data are strongly indicating that the research work was successful. The synthesized dye showed reversible color change from reddish-orange to violet under a UV light due to conversion of the colorless spirooxazine moiety to the merocyanine form which is blue. The dye was then applied on cotton. Color strength ( K/ S) values of the synthesized dye on cotton at various amounts of salt, alkali, and dye concentration were measured. Optimal amounts of salt (15 g/ l), alkali (15 g/ l) and dye concentrations (4 %) were obtained. The color change properties and the technical performance of the photochromic cotton samples were evaluated using color measurement methods. The data were analyzed in terms of color difference before and after exposure and K/ S curves as a function of irradiation time. The fading speed was found to be slower than the photocoloration and the samples generally showed good wash fastness. The synthesized dye showed migration index of 67 %. [ABSTRACT FROM AUTHOR]

In this paper, two inorganic salts including sodium chloride and sodium sulfate were used for investigating their effects on the photocatalytic decomposition of three reactive dyes including C. I. Reactive Red 195, C. I. Reactive Blue 222, and C. I. Reactive Yellow 145 in water using Fe (III)-oxalate complex/HO system under sunlight irradiation. Some important variables such as nature of inorganic salts, dosage of inorganic salts, and intensity of solar irradiation were examined with respect to decoloration percentage or kinetic reaction constant. Their photocatalytic degradation mechanism was examined by ESR analysis, UV-Vis spectrum, and TOC measurement. The results indicated that photocatalytic decomposition of three dyes is reduced significantly by the presence of sodium chloride during cloudy day. Moreover, increasing concentration of inorganic salt in water could give rise to low decoloration efficiency. Sodium chloride exhibited much stronger reduction retardant effect on decoloration than sodium sulfate under solar irradiation. In addition, the decoloration of three dyes can be described by using the pseudo-first order kinetics in the presence of inorganic salt during sunny or cloudy day. However, the reaction rate constants decreased with the concentration of sodium chloride increasing, particularly during cloudy day. [ABSTRACT FROM AUTHOR]